Interesting info on B3702 Injection timing [Archive]

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LS1_Dragster

June 28th, 2009, 04:08 AM

I messed with this value on my 454 and it seemed to make it run a little better at idle so I figured I would mess with it on my wife's dragster.

The dragster has a 2001 LS1 with PRC 2.5 Heads and MS3 cam, all else is stock and has 80K miles on it.

First run at the track was with no changes from prior runs for the past year, corrected altitude was 7123 and the times were typical for the D/A:

60 -> 1.338
1/8 -> 5.899
MPH -> 116.65
1/4 -> 9.270
MPH -> 145.02

Did nothing but add 20% to B3702 across the board. The next run the D/A was 7380 which is little worse then the first run:

60 ->1.305
1/8 ->5.822
MPH ->117.73
1/4 -> 9.164
MPH ->146.38

It was a pleasant surprise to see such a huge reduction in ET. At this point the WB02 was reading rich so I leaned it 2% and it ran:

60 -> 1.311
1/8 ->5.801
MPH -> 119.01
1/4 -> 9.103
MPH -> 148.44

We're talking .17 reduction because I changed the injector timing which in turn show it running too rich. Keep in mind that the program I have has been running since last year and being a dragster what extremely consistent, so this is a true reduction.

Next time out I will get the WB02 correct then add some more to B3702 and see if there is even more to be gained. It's amazing how the air/fuel mixture changed so much....

Food for thought.

Lee

5.7ute

June 28th, 2009, 04:33 PM

Thanks for posting that info Lee.
Just to complicate things a bit, what injectors are being used in this combo? & what duty cycle are they maxxing at?
I have lost a couple of mph since upping the injectors for a dry nitrous shot, all other things being equal & was going to be looking at this table. I believe the smaller pulsewidth for the larger injectors is not getting a decent mix in the cylinder. Hopefully I should be getting back on the dyno before the 1320x meet here & will post any thing I can add to your findings.
Cheers Mick

LS1_Dragster

June 29th, 2009, 12:34 AM

The injectors are accel 36#, fuel pressure is 50# max duty cycle is 71% and max 13ms.

I can only assume that since the cam is larger then stock it's going to be opening way sooner so by adding to the table it sprays closer to when the valve is closed so it gets better atomization.

It also makes sense why it shows running richer afterwords. If the fuel wasnt atomizing and some raw fuel was was leaving the head it would tend to cool the O2 and give a false lean condition. I estimate that it's probably around 5% too rich after this change.

Cant wait to make more changes next time out!

Lee

joecar

June 29th, 2009, 03:06 AM

Very interesting, thanks for posting.

LS1_Dragster

July 16th, 2009, 01:04 AM

Just an update:

Took the dragster out last night and played with injector timing on one run. I increased the value 15% more and reduced the et by .070.

I wanted to experiment more but it was only the last two runs for that setting to verify the next run wasnt a fluke. Both runs picked up .07 with the identical DA.

Here's the data for B3702:

LABELS Injection Timing (mS)
ECT °F {link: SAE.ECT} Value
-40 3.523438
-18 3.523438
3 3.523438
25 3.523438
46 3.523438
68 3.523438
90 4.902344
111 6.281250
133 6.281250
154 7.660156
176 7.660156
198 7.660156
219 7.660156
241 7.660156
262 7.660156
284 7.660156

And B3703:

LABELS Injection Timing Trim (mS)
ECT °F {link: SAE.ECT} Value
-40 7.660156
-18 7.660156
3 7.660156
25 7.660156
46 7.660156
68 7.660156
90 7.660156
111 7.660156
133 7.660156
154 7.660156
176 7.660156
198 7.660156
219 7.660156
241 7.660156
262 7.660156
284 7.660156

Next time out I will increase it more and see what happens.....

Lee

joecar

July 16th, 2009, 05:43 AM

LS1_Dragster

July 16th, 2009, 05:56 AM

Another interesting fact:

The WBO2 showed 1.3% richer then the previous run. The first time I changed the tables a few weeks ago it showed more like 5% richer afterwards. Since it showed a smaller percentage maybe it's closer to optimal now. When I get a chance again in the future I will up it again. If I remember right it max's out at 8.0ms.

It would be interesting if someone else could back up this data at the strip....

Lee

dfe1

July 17th, 2009, 04:24 AM

The reduction in ET is impressive, but I've found that it is often difficult to correlate some modifications to improvements in elapsed times. On the other hand, mile per hour is typically a very reliable indicator of horsepower. What I find particularly impressive about Lee's results is the improvement in mile per hour-- a 1.3 mph improvement from changing injector timing is HUGE, as is 3 miles per hour resulting from injector timing and mixture changes. That kind of mile per hour improvement indicates that definite horsepower increases should show up in dyno testing

GAMEOVER

July 17th, 2009, 04:33 AM

This thread is very interesting!!!

redhardsupra

July 17th, 2009, 04:52 AM

LS1_Dragster

July 17th, 2009, 05:25 AM

Definitely interesting, I wish I was smart enough to tie this into valve timing events with the aftermarket cams, I'm just curious as to when it injects in relation to when the intake opens.

BTW, we ran it 5 times Wednesday, the last two were no changes except the 15% added on run 4. The MPH gain compared to the prior 3 runs was .89. The DA was 7397 on run 4 and 7340 on the last. The average of the first 3 runs is 7331 so you can see that the air was real close.

Also, the first 3 60' times averaged 1.358 and the average of the last 2 was 1.337, according to my crew chief pro software it picks up across the board each time. It's running the same times now at 7300' DA as it did in 6400' DA at the beginning of the year and I've done nothing to the dragster but play with the injector timing tables and the AFR since it showed richer.

Lee

redhardsupra

July 17th, 2009, 06:04 AM

i found a spreadsheet for ford computers that demo'ed/explained a lot of this stuff. i modified it to work with some typical gm values. of course it was a hypothetical exercise as we dont have the same sort of injection tables as ford, but it definitely broadened my understanding of this. i'll try to find my version of the spreadsheet tonight, it should be helpful. kinda fun to watch injection angles change as you 'swap cams' ;)

edwardzracing

July 17th, 2009, 09:09 AM

Hi Lee,

Very interesting stuff here. I was at the same test & tune with my '98 Camaro. Wish I would have known you were from Utah, I would have tried to track you down. What color is your dragster? Is it easy to spot? I don't know anybody else in the state with EFILive, so this is definitely an interesting find. I'd love to test some of your findings with my car as I definitely have some work to do. Untuned the car still went 12.29 at 110.28. I think it's got more in it, but I have a lot to learn still. Great job on your results. Hopefully I'll run into one of these days.

Brad

LS1_Dragster

July 17th, 2009, 09:42 AM

Hi Brad, I did see a few camaro's but I didnt pay too much attention, I was too concerned about dying from the heat!

I've tuned 3 vehicles with EFI Live and it's been a challenge, the Holley commander 950 is MUCH easier! But using a factory computer and harness is way cheaper so I need to get the tuning down pat.

Here's a picture of the dragster:

http://www.horsepowerracing.com/dragster_m.jpg

We're mainly just going to the big events this year so we'll only be out a few more times. I only hit this TnT to see what the injector timing was going to do....

Lee

dfe1

July 17th, 2009, 12:44 PM

wouldn't injection timing be very dependent on valve events? i know that most OEM calibrations do injection against a closed valve, but if the timing wasnt important, they wouldnt have the table for it, would they?
I really wonder about that. Seems logical that it would be, and Lee's testing seems to prove that. Someone should do a bit of testing with an engine that has a stock cam and see if results are similar. It may well be that GM decided to trade off some power for improved emissions numbers.

I don't know if this is relevant, but when GM switched from batch to sequential (for the 1994 model year) the engineers stated that there wasn't much difference in power. The switch to sequential was primarily a result of the need to improve emissions and economy. I was somewhat doubtful at the time, and have become more so over the years. I don't know that they were "mis-speaking" as much as the computers of the day may not have had the capacity to alter injection timing. It may also be that the engineers were basing their comments on little or no comparative testing. If they were chasing emissions, they probably didn't look at power. Sounds strange, but on at least one occasion, when I asked about results outside the operating range of the program focus, I had engineers say, "I don't know, we didn't test there". Be interesting to do a back-to-back batch-to-sequential test and see what the power difference is.

LS1_Dragster

July 17th, 2009, 02:52 PM

The holley MPFI is batch mode and I had a 975HP 632 pump gas running like a hot street car, idled at 950 RPM like a kitten. During my testing with these units I was in close contact with a Holley engineer and I was told on many occasions that batch vs. sequential resulted in no power difference and it was implemented for emissions. I have heard that the boosted guys out there are getting more reliable power with sequential....

All in all though, I've seen a huge drop in et and gain in MPH from a setup that we've been running for 1.5 years and has 72K miles on it, so no engine break in, new tires or any change what-so-ever mechanically or otherwise to account for the reductions by just changing this parameter!

exploder

July 23rd, 2009, 07:26 AM

anything new on this subject...has anybody else tried this?

5.7ute

July 23rd, 2009, 03:27 PM

anything new on this subject...has anybody else tried this?

I had booked some dyno time to have a play with this a few weeks ago. Unfortunately the dyno operators car took precedance over mine & after two days of being stuffed around I cracked the shits & gave up.:chair:
We have a 2 day meet next weekend, so if I can get some consistant runs in I will give it a shot.

dfe1

July 25th, 2009, 01:23 PM

LS1_Dragster

July 25th, 2009, 01:31 PM

I haven't had a chance to do any testing, but it seems logical that optimum injector timing is somewhat dependent on valve timing. My guess is that Lee has a pretty aggressive cam in his dragster engine, which is the reason it responded so well to the change in injector timing. Might be a good idea to include cam duration along with the data pertaining to values and results of injector timing experiments.

Sorry, here's the specs:

TSP XS Series Camshaft:
Magic Stick V.3 237/242 .603/.609" 112 lobe sep. Camshaft.

The Magic Stick V3 camshaft is Texas Speed's premier LS1 camshaft! This camshaft has gone as fast as 10.50s n/a with stock heads in our 98 Z28 test car.
This camshaft features Comp Cams XER lobes! The XER lobes have been proven to make big horsepower & torque thanks to their aggressive ramp rates & healthy lift.

2300-6800 RPM Power Band with a peak around 6400rpm; This is an excellent performance camshaft with a rough idle! Custom tuning required

Highlander

July 25th, 2009, 07:50 PM

Sorry, here's the specs:

TSP XS Series Camshaft:
Magic Stick V.3 237/242 .603/.609" 112 lobe sep. Camshaft.

The Magic Stick V3 camshaft is Texas Speed's premier LS1 camshaft! This camshaft has gone as fast as 10.50s n/a with stock heads in our 98 Z28 test car.
This camshaft features Comp Cams XER lobes! The XER lobes have been proven to make big horsepower & torque thanks to their aggressive ramp rates & healthy lift.

2300-6800 RPM Power Band with a peak around 6400rpm; This is an excellent performance camshaft with a rough idle! Custom tuning required

That is pretty much the Cam I have on my Pops z06. I chose it for the stretch in power. I will be experimenting with this on my dyno.

mvvette97

July 27th, 2009, 05:29 PM

I would like to hear more about this also.

9secVette

July 28th, 2009, 02:00 AM

I will do some dyno testing as well, thanks for posting your results. :cheers:

DrkPhx

July 28th, 2009, 10:57 AM

After reading this thread I was curious so I decided to increase the values as described here. Increasing the injector timing by 20% caused the entire tune (idle, part throttle, and WOT) to go way lean. So then I decreased the injector timing values for a net increase of 5% over stock values and the tune was still lean though not as bad as before. Oddly enough the injector duty cycle went up across the board with the increased timing values. In each case I adjusted both the VE and MAF values help compensate but in the end I went back to my existing tune.

LS1_Dragster

July 28th, 2009, 11:02 AM

Is your cam and heads stock?

redhardsupra

July 28th, 2009, 11:02 AM

DrkPhx, do you have the logs? this is seriously interesting what you've observed.

5.7ute

July 28th, 2009, 11:21 AM

DrkPhx, do you have the logs? this is seriously interesting what you've observed.

x2
Is there any chance your fuel trims were trying to compensate for the lean condition & increasing the commanded pulsewidth?

DrkPhx

July 28th, 2009, 11:40 AM

Is your cam and heads stock?

I'm far from stock. It's an auto car with a large stall and a highly modified, high compression 402 with a fairly large cam. I run 42-lb Delphi injectors with the fuel pressure set at 61 psi (at the rail measured with a mechanical test gauge). I confirmed the lean condition with both the LTFT's and a LM-1 WB which is used for all logs.

DrkPhx, do you have the logs? this is seriously interesting what you've observed

I'm still looking for the logs (one was quite long) but I use the BBL function and never renamed the logs when I uploaded them to my laptop. I can't search by date either because the time and date isn't real time when using the BBL.. I will keep searching and post it up when I find it.

DrkPhx

July 28th, 2009, 12:00 PM

I found one of the logs. It's not as big as I thought, but there's enough data there to see what happened. As you can see in the log, the car seemed to get progessively leaner towards the end of the log.

LS1_Dragster

July 28th, 2009, 04:05 PM

School me, I must be looking at your log incorrectly, I dont see the "way lean" condition. If I take your entire log over 190 degree, I show the average stft to be .06 and .08

Lee

mvvette97

July 28th, 2009, 04:32 PM

ok so you add or subtract from table B3702? I would like to play with this as well. I looked at my stock tune for my vette and then the trans am and both of them are different from each other. I figured they would be the same but they aren't

DrkPhx

July 28th, 2009, 10:57 PM

School me, I must be looking at your log incorrectly, I dont see the "way lean" condition. If I take your entire log over 190 degree, I show the average stft to be .06 and .08

Lee

The LTFT's are way high.. +16-18% on average for most of the log. Look at commanded AFR vs actual in frame 3726. Commanded is 13.09 and actual is 13.81. Before the timing adjustment, the WB was lower than the commanded at 12.8-12.9 at the same spot. So it's definitely leaner. In addition the car sputtered at part throttle, especially from a stop up to speed.

LS1_Dragster

July 29th, 2009, 12:32 AM

I wonder why mine responded so well, remember mine went rich not lean. My 454 in my firebird also responded well, no track time but just idling and cruising was noticeable.

There are 2 main differences from both my cars: 1) the intake and throttle body on both are using the edelbrock vic jr. and the holley TB 2) The dragster has open headers.

Maybe something in those mods are making the difference?

LS1_Dragster

July 29th, 2009, 12:42 AM

DrkPhx,

What size cam and what's your altitude there?

Also, I thought about something else, the dragster never sees temps over 160 and is usually 145 at the starting line and the firebird never sees over 165, even on hot days. Maybe the cooler temps need more time to atomize the fuel?

LS1_Dragster

July 29th, 2009, 12:51 AM

dfe1

July 29th, 2009, 01:26 AM

I have so many questions!

Why does the LTFT go so high when the STFT don't reflect that? I figured the LTFT are an average of the STFT. I can only log STFT because I'm semi-closed loop because I want to use table B3647 for my commanded AFR. So if my STFT are looking OK like yours is it really OK?? Or or am I lean like yours?
In closed loop, the short term trims ratchet the long term trims up or down as required. Essentially, STFT adds or subtracts fuel as required. If it goes to maximum value and AFR still isn't correct, LTFT bumps and the process repeats until STFT can maintain proper AFR while staying within a specific range. So if a calibration is way off, you'll usually see a fairly large LTFT percentage number and a small STFT percentage number.

eficalibrator

July 30th, 2009, 02:21 AM

OK, it looks like the info here went sideways pretty hard...

Before adjusting injection timing, it's important to understand why it's there. Most OEM applications are timed to inject fuel against a closed intake valve. This does two things; it cools the valve and aids in evaporation. When the engine is cold, fuel takes longer to evaporate, so it must be injected sooner to get enough of the liquid evaporated to enable clean combustion.

Clean combustion is the key here. If you're burning everything you injected and you had decen charge mixing, it shouldn't matter as much when you injected it. On the other hand, if you're either not burning liquid fuel in the chamber or not mixing completely, it can skew what you think got injected into the cylinder. This is why the OE calibration injects earlier on a cold engine to allow time for fuel to evaporate and mix prior to combustion. (Look at the table and you'll see the trend!)

In the aftermarket, we have the nasty habit of plugging huge cams into engines that open the door for a couple problems. One is that the lower port velocity reduces charge mixing at low engine speeds. The other is that having both valve open simultaneously (during overlap) opens the door for "short circuiting" where vaporized fuel may escape out the exhaust valve without ever being burned if there isn't sufficient port velocity to push it down into the cylinder. This can usually be addressed by delaying the injection event slightly so that the vapor isn't there when the exhaust valve is open. The potential downside is that large quantities of liquid fuel being injected into a cylinder at low port velocity may lead to bore wash at extended idle.

If you see a change in AFR resulting from injection timing, it just means that you didn't get a complete burn in one case. The object is to completely evaporate and burn whatever fuel you inject, regardless of what's going on with the aircharge or port velocity. This was one of the exercises we did in my last advanced GM tuning class with a 23x+ camshaft in a GTO. Once you find clean combustion, it's a lot easier to dial in the VE (or VVE) tables, THEN you can address idle airflow targets.

mr.prick

July 30th, 2009, 04:14 AM

So, is there a method to change the injection timing or is this something that
must be done before the car starts like the IFR and pulse adjust tables?

eficalibrator

July 30th, 2009, 05:18 AM

Yes, you can change injection timing during the tuning process. You are correct that IFR, offset, and short pulse adjust are fixed prior to operation and injection timing is adjustable. I typically leave it alone unless I have trouble getting a clean burn (usually at idle on bigger cams). If it must be adjusted, I'll add injection delay as necessary to get a clean lambda signal from my (high quality) wideband and a smoother idle. The trick is to only add just enough delay to clear things up while still allowing for the maximum amount of evaporation and mixing time.

mr.prick

July 30th, 2009, 05:23 AM

Just X-amount-% gradually?

DrkPhx

July 30th, 2009, 05:30 AM

EFICalibrator - Thanks for the explanation. That's great information to know.
Like Mr Prick asked; is there a basic formula to use?

eficalibrator

July 30th, 2009, 05:49 AM

It's hard to give you a single formula that will work most of the time since you guys all like to pick snowflakes for cam and head combinations. (No two are alike) To make things worse, different ECUs describe the timing with different units. Some use degrees of crankshaft rotation relative to TDC, others degrees relative to BDC, and many GM ECUs use "cam reference pulses." The cam reference pulse is still a unit of angle (which is time at a fixed RPM), so you're really tuning how much time "lead" you're giving the fuel delivery much like ignition timing. Just like ignition, there's a sweet spot that gives better results and it's possible to go too far. This is one of those grey areas that more experienced calibrators end up building a "feel" for as they do more of them.

5.7ute

July 30th, 2009, 02:29 PM

That is a great explanation Greg, thanks.:cheers:

dfe1

July 31st, 2009, 04:56 AM

OK, it looks like the info here went sideways pretty hard...

If you see a change in AFR resulting from injection timing, it just means that you didn't get a complete burn in one case. The object is to completely evaporate and burn whatever fuel you inject, regardless of what's going on with the aircharge or port velocity. This was one of the exercises we did in my last advanced GM tuning class with a 23x+ camshaft in a GTO. Once you find clean combustion, it's a lot easier to dial in the VE (or VVE) tables, THEN you can address idle airflow targets.

Greg- What did you find in your experiment with the 230+ cam. As I see it, if you go strictly by intake valve opening point, the values in B3702 should theoretically be reduced with a long duration cam because valve opening occurs "sooner" (more degrees before TDC). The situation is similar to that of a cold engine- the injector has to fire "sooner" to provide adequate atomization time. If the intake valve opens earlier, then it would stand to reason that you also have to fire the injector sooner to promote atomization. If you delay opening (with a larger number in B3702) then the injector is likely to be firing against an open, rather than a closed valve. However, you state that you "add delay" if necessary when tuning engines with aggressive cams, but stock offset values are smaller at low temperatures than they are at high temps. I'm trying to reach a logical conclusion and things just aren't adding up, which to me indicates that overlap is a more important consideration than intake valve opening point.

Highlander

July 31st, 2009, 07:49 AM

Greg- What did you find in your experiment with the 230+ cam. As I see it, if you go strictly by intake valve opening point, the values in B3702 should theoretically be reduced with a long duration cam because valve opening occurs "sooner" (more degrees before TDC). The situation is similar to that of a cold engine- the injector has to fire "sooner" to provide adequate atomization time. If the intake valve opens earlier, then it would stand to reason that you also have to fire the injector sooner to promote atomization. If you delay opening (with a larger number in B3702) then the injector is likely to be firing against an open, rather than a closed valve. However, you state that you "add delay" if necessary when tuning engines with aggressive cams, but stock offset values are smaller at low temperatures than they are at high temps. I'm trying to reach a logical conclusion and things just aren't adding up, which to me indicates that overlap is a more important consideration than intake valve opening point.

Often times the timing is to the degree where the intake valve closes LATER in the compression stroke, not that much sooner. If the piston is still going up in the exhaust stroke and you open the valve you will get too much reversion... As RPMs go up overlap helps fill the cylinders better, so i get why you would want to delay the injector firing because you will want to fire it where there is more air speed.

Goldfinger911

August 4th, 2009, 05:02 PM

This is very interesting. I did a lot of experimentation with this:
http://forum.efilive.com/showthread.php?t=9288

I have a custom cam, but similar to the MS3. Here is what I came up with.... I think your results lend some merit to mine. Thanks and keep us posted.

--cut--
-1 RPM = 360deg crank rotation
-1000rpm = 360000 deg <---- typical big cam idle and to keep the math easy
-16.67 revolitions per second
-6000 degrees of rotation per sec
-0.0167 revs per ms
-6 degrees of rotation per ms
-Therefore when advancing the intake opening event by 2 deg, this means firing the injector .334 ms sooner.
--cut--

SSpdDmon

August 5th, 2009, 01:50 AM

5.7ute

August 5th, 2009, 09:57 AM

I wonder what this means for someone like me who is running a 60# injector in a stock engine? It seems I'm always fighting a rich condition at idle. I had assumed that was because I couldn't get the pulse width short enough. So, my "solution" was to zero out the small pulse adjust (B4005) and start pulling time out of the voltage table (B3701). Now, I'm wondering if my problem is because the bigger injector is slower to open....and therefore I need to reduce the offset in the timing table. http://www.motownmuscle.com/forums/images/smilies/mmm.gif

Jeff, I would think that you would cause more problems & not actually solve the issue you are having. Your problem is the injectors cannot supply a small enough amount of fuel to give a stoich idle. Offsetting the injectors may change your wideband reading but you will still have too much fuel for the operating conditions.

eficalibrator

August 5th, 2009, 02:45 PM

I wonder what this means for someone like me who is running a 60# injector in a stock engine? It seems I'm always fighting a rich condition at idle. I had assumed that was because I couldn't get the pulse width short enough. So, my "solution" was to zero out the small pulse adjust (B4005) and start pulling time out of the voltage table (B3701). Now, I'm wondering if my problem is because the bigger injector is slower to open....and therefore I need to reduce the offset in the timing table. http://www.motownmuscle.com/forums/images/smilies/mmm.gif

No, the fundamental problem is more likely that you have incorrect data for both short pulse adjust and offset tables. Both of these have a very large impact upon pulsewidth calculation at idle and cruise. If you're not properly converting from desired fuel mass to actual injection time, you have little hope of getting much else right.

SSpdDmon

August 6th, 2009, 12:25 AM

No, the fundamental problem is more likely that you have incorrect data for both short pulse adjust and offset tables. Both of these have a very large impact upon pulsewidth calculation at idle and cruise. If you're not properly converting from desired fuel mass to actual injection time, you have little hope of getting much else right.
Well Greg, it's been my experience that you can only shorten up the IPW so far by adjusting down your IFR, MAF, or VE before you hit a wall with bigger injectors. At that point, you need to pull time out of the voltage adjustment and short pulse width tables. I've searched around and found what appears to be the right voltage adjustment numbers. But even with the short pulse table zero'd out, I'm still seeing 11:x AFRs at idle, which is why I was pulling more time out of the voltage table.

If you have some insight on how to correct this, I'm interested in listening to what you have to say (as are others I'm sure). However, just coming in the thread to essentially say "you're doing it wrong" and not offering suggestions isn't really helpful. It's frustrating. I understand you need to sell books and DVD's. But, I'd honestly rather you not post at all if that's all you have to offer.

eficalibrator

August 7th, 2009, 12:15 PM

...you need to pull time out of the voltage adjustment and short pulse width tables. I've searched around and found what appears to be the right voltage adjustment numbers. But even with the short pulse table zero'd out, I'm still seeing 11:x AFRs at idle, which is why I was pulling more time out of the voltage table.
I'm inclined to agree with you here. I just didn't go that far down the path in my first post since I thought it was self-evident. What you're most likely finding is that the ACTUAL offset really is shorter and needs to be recalibrated. The offset and short pulse adjust make up a very large percentage of the total idle pulswidth, so an oversized offset can have a very real impact upon your ability to get back to stoich. You're heading down the right path, it's just easier if you start with the proper data rather than trying to stumble upon it.

dfe1

August 7th, 2009, 02:23 PM

This thread still seems to be going sideways. If an injector in a sequential system fires against a closed valve, then as cam duration increases, the question is should injector offset be increased or decreased? Lee's testing showed improved performance be increasing offset, but to me that doesn't match the logic of the concept-- unless there's a benefit to firing the injector closer to valve open, or after the valve has opened. The reference pulse has to occur before the injector fires and that being the case, increasing offset will delay injector firing. If the idea is to give fuel more time to vaporize, then offset should be reduced to compensate for an earlier opening intake valve (than with a stock cam).

It's interesting to note that the injection timing tables (B3702) for truck, LS1 and LS6 are identical, (even though cam duration varies quite a bit) although the values for the G van are slightly larger. What's also interesting is that the E40 and E38 ECMs have injector timing versus RPM tables and the values (expressed in degrees) generally increase with rpm. On the other hand, values in the timing versus ECT table (also expressed in degrees) are higher at low coolant temps than they are at higher temps. (Opposite of value change in an LS1 PCM). I'm trying to make sense of all this and not being very successful. Every time I think of a reasonable explanation, I find something that contradicts it. Any ideas?

drdarthinvader

August 8th, 2009, 03:56 AM

1. is b3702 a delay in opening the injector?
2. is b3701 a compensator to a slow opening injector? note :that aust and usa tables are different but tables in b3702 are the same

5.7ute

August 9th, 2009, 10:32 AM

LS1_Dragster

August 9th, 2009, 11:03 AM

I was reading an article the other day about direct port injection and one of the things it mentioned was firing the fuel near the top of the piston stroke on a cold motor for better emissions etc. This would explain why the injection times are lower when cold, they are firing the injector with the valve open. I guess they don't need the raw fuel puddling when it's cold.

dfe1

August 10th, 2009, 01:18 AM

The offset when increased will have the injector fire earlier not later.
That appears to be the case, I'm just trying to understand the algorithm. If a larger number means the injector is firing earlier, then the value would have to be subtracted from a base delay, I'd guess. If that's the case, then the injectors fire at reference pulse+delay-offset.

Gelf VXR

September 29th, 2009, 09:24 PM

Some of us are trying to figure out what crank/cam/valve event the injector timing tables are relative to (e.g. time BBDC...?)...

We appreciate your efforts in experimenting with this...:cheers:

5.7ute (Mick) is very interested in this.

Hi Joe

I believe the injector timing is in crank regress and relative to TDC on the compression stroke?

Foe example on the LS2 the advance is 490 degrees when cold and 220 degrees at normal running temps, so the timing events for the LS2 are as follows:

Engine cold

Inj fires. 130 BTDC. CLOSED INLET VALVE
IVO. 16 ATDC
ICL. 118 ATDC
IVC. 40 ABDC

Engine hot

IVO. 16 ATDC
ICL. 118 ATDC
Inj fires. 140 ATDC. INLET VALVE BEGGINING TO CLOSE
IVC. 40 ABDC

LS1_Dragster

September 30th, 2009, 01:25 AM

From what I've been reading, the cold injection event is more beneficial to happen when the valve is open and closer to TDC, they dont want raw fuel puddling up on cold walls. Also, the articles state that it helps light off the catalytic converter.

Lee

joecar

September 30th, 2009, 02:39 AM

Hi Joe

I believe the injector timing is in crank regress and relative to TDC on the compression stroke?

Foe example on the LS2 the advance is 490 degrees when cold and 220 degrees at normal running temps, so the timing events for the LS2 are as follows:

Engine cold

Inj fires. 130 BTDC. CLOSED INLET VALVE
IVO. 16 ATDC
ICL. 118 ATDC
IVC. 40 ABDC

Engine hot

IVO. 16 ATDC
ICL. 118 ATDC
Inj fires. 140 ATDC. INLET VALVE BEGGINING TO CLOSE
IVC. 40 ABDCHi Gelf,

That does make sense (relative to TDC compression stroke)...

The LS2 injector timing is directly in degrees... makes visualization easier...:cheers:

The LS1 injector timing is in milliseconds, so I have to convert that to degrees based on rpm:

offset[°BTDC] = 720 * Toffset * RPM/120000

where Toffset is in ms,

range of Toffset B3702 is 0° to 8°, so offset[°BTDC] range is 0° to 288° (at 6000 rpm)... does this make sense...?

BTW: oh, your IVO would be 16° BTDC (to give you ICL 118°).

Gelf VXR

September 30th, 2009, 03:11 AM

BTW: oh, your IVO would be 16° BTDC (to give you ICL 118°).

Are you sure? 118 centre line, intake duration 204 degrees @ 0.05

118 ATDC - 102 = 16 ATDC

joecar

September 30th, 2009, 03:28 AM

Goldfinger911

September 30th, 2009, 04:32 AM

This is great info.

So... what about when you have a cam that has a lot of overlap? The LS1 and LS2 cams have none (negative overlap); so moving the injector firing event back and forth can be done within a pretty wide window. My cam is a custom grind for the track, and has a lot of duration, a 110 deg ICL and 21 degrees of overlap... so now the EVO event comes into play a whole lot more. Would you want the injector firing even earlier to take advantage of the pull-through effect of the exhaust? Or later, to minimize unburnt fuel passing through the cylinder?

Goldfinger911

September 30th, 2009, 04:49 AM

Hi Joe

I believe the injector timing is in crank regress and relative to TDC on the compression stroke?

Foe example on the LS2 the advance is 490 degrees when cold and 220 degrees at normal running temps, so the timing events for the LS2 are as follows:

Engine cold

Inj fires. 130 BTDC. CLOSED INLET VALVE
IVO. 16 ATDC
ICL. 118 ATDC
IVC. 40 ABDC

Engine hot

IVO. 16 ATDC
ICL. 118 ATDC
Inj fires. 140 ATDC. INLET VALVE BEGGINING TO CLOSE
IVC. 40 ABDC

The injector firing event of #1 cylinder is based off the crank trigger at TDC on #1. Also known as tooth #0 (on a 48 tooth crank trigger; 7.5 deg per tooth).

I have been playing with "a brand-x stand-alone EMS" on my LS1 and you can set the ignition and injector firing events of each cylinder by degree or tooth. More importantly you can see exactly when the injector is firing in both ways as well.

The reason I bring this up is I was amazed to see how a slight movement of the injector firing event affects idle, AFR, idle load, and throttle response. You also immediately notice things like, your AFR getting leaner on the gauge, but the exhaust smelling like unburnt fuel. So far, adjusting the event so as to yield the richest idle mixture (the most burnt fuel at a fixed pulse width) seems to get me closest to optimal with everything else.

Gelf VXR

September 30th, 2009, 05:48 AM

Oh, your duration is 204...?

Then you're right, your IVO is 16 ATDC (usually it's BTDC)... :)

(I thought it was 236, but maybe I'm thinking of someone else's cam).

What are your cam specs again...?

Yes, i was reffering to the stock calibration and cam - 204/211 118ICL and 216LSA

My cam is 216/229 113ICL and 113LSA

Intake opens ~ 11-13 degrees earlier, ICL is 5 degrees earlier, inlet closes around the same time.

I propose to advance the B3702 5 degrees @ normal running temps in relation to the ICL.

I'm thinkin the optimum injector timing event is after the ICL event where intake velocity is highest and optimum for evapourating all the fuel.

Gelf VXR

September 30th, 2009, 05:55 AM

The reason I bring this up is I was amazed to see how a slight movement of the injector firing event affects idle, AFR, idle load, and throttle response. You also immediately notice things like, your AFR getting leaner on the gauge, but the exhaust smelling like unburnt fuel. So far, adjusting the event so as to yield the richest idle mixture (the most burnt fuel at a fixed pulse width) seems to get me closest to optimal with everything else.

I was considering the the exhaust valve timing when cold, if the valve is open later, then perhaps the timing should be retarded in line with the difference from the stock cam. For example the stock cam closes 6 BTDC, my cam closes 1.5 ATDC, so I might need to retard 7 or 8 degreeswhen cold??

Goldfinger911

September 30th, 2009, 06:26 AM

I was considering the the exhaust valve timing when cold, if the valve is open later, then perhaps the timing should be retarded in line with the difference from the stock cam. For example the stock cam closes 6 BTDC, my cam closes 1.5 ATDC, so I might need to retard 7 or 8 degreeswhen cold??

Hmm. Thats what I was thinking. Regarding cold running... when my car starts up... the tune does retard timing and it sounds very mean out the tail pipe. The AFR is rich, but very stable. I have always wondered about this when cold.

Wait... what stock cam has the EVC at 6 deg BTDC? I thought the stock LS1 EVC was 10.5 deg and the stock LS2 was 8.5 deg BTDC?

Mine is a bit more challenging to tune for; 242/248 .612"/.617" 112+2 LSA 110 ICL.

Gelf VXR

September 30th, 2009, 08:26 AM

Stock cam specs attached

Goldfinger911

September 30th, 2009, 08:48 AM

I dont want to sidetrack the thread.. but an LS2 cam has an LSA of 116 right? It would have to to give you an ECL of 114. Even though... the math doesnt work out right on the open and close events.

For example, isnt IVO = ID/2-ICL ? I think those numbers are incorrect.

Gelf VXR

September 30th, 2009, 06:52 PM

eficalibrator

October 1st, 2009, 04:28 AM

So far, adjusting the event so as to yield the richest idle mixture (the most burnt fuel at a fixed pulse width) seems to get me closest to optimal with everything else.

In the context of tuning large overlap cams, with an emphasis on throttle response and idle control, this should work fine. (It may negatively effect emissions) Keep in mind that any previous VE or MAF mapping done in the reversion sensitive region will probably need to be revisited now that you have a cleaner wideband signal.

Gelf VXR

October 8th, 2009, 07:16 AM

I heard back from the garage carrying out my cam and head install today, they said the idle is smooth. This is stock LS2 and tune with LS7 injector calibrations with L92 heads, comp 216/229 cam.

One interesting difference I noticed with the injector calibrations for the injector timing when you add the ECT + RPM advance tabes, from 0 to 1020 rpm. Apart from that identicle.

The LS7 calibration has 20 to 65 degrees more advance than the LS2.

Gelf VXR

January 23rd, 2014, 10:45 PM

Bumping this old thread, it seems I made an error thinking injector advance was referenced to TDC on the power stroke

Stock LS2

Engine hot

IVO. 16 ATDC
ICL. 118 ATDC
Inj fires. 140 ATDC. INLET VALVE BEGGINING TO CLOSE
IVC. 40 ABDC

The injector couldn't possibly open as the inlet valve closes, could it?, the advance must be referenced to TDC on the induction stroke inlet valve opens. The injector opens 220 BTDC inlet opens / 140 ATDC ignition stroke, just after/during the combustion event, spraying onto the closed and very hot inlet valve, cooling it in the process and vaporising the fuel. Ref: RC engineering in this thread http://www.chevytalk.org/fusionbb/showtopic.php?tid/199007/

The injector open & close time in relation to crank angle is variable depending on rpm (opens) and injector duty cycle (closes), there doesn't seem to be any fixed correlation to the inlet or exhaust valve timing events other than the injector closes variable time before the inlet valve opens, it is only when high rpm and 85% duty cycle is reached that the injector close time will be after the inlet valve has opened. See attached

For example at say injector duty cycle 85% is equal to 15ms @6400rpm, 1ms = 38 crank degrees, 15 x 38 = 570 degrees

720 - 570 = 150 degrees, the duration of stock cam is 204 degrees, its impossible for the injector to open and closed during the inlet valve closed duration.

Intuitively I would think that if there is any tuning to be done to injector timing its with regard to opening the injector at the optimum crank angle for the combustion event when the inlet valve is hottest to make the most of vaporisation and time before the inlet valve opens?? If your injectors are open when the inlet valve is open, time for larger injectors???

joecar

January 23rd, 2014, 11:50 PM

Hi Gelf,

Injectors are not necessarily fired at open intake valves... actually most of the time they are fired at closed valves.

Gelf VXR

January 24th, 2014, 12:22 AM

Hi Joe

Yes, tuning injector advance so that it opening during the power stroke when the inlet valve is closed and at its hottest or earlier to ensure enough time for vaporisation well before the inlet valve opens, maybe even more so with overlap and open exhaust valve?

If your injectors are maxed out, you'll still be injecting with the inlet valve open

5.7ute

January 27th, 2014, 01:33 PM

The way I understand it is the reference point is the end of injection, not start. So the end of injection is constant & the start varies.

Gelf VXR

January 27th, 2014, 08:45 PM

I'm trying to understand, I checked the B3702 description as I was referring to LS2 data, but it is the same for LS1

B3702 LS1

"This table will offset the actual opening of the injector referenced to the reference pulses and engine coolant temperature"

B1205 LS2

"This table will offset the actual opening of the injector referenced to engine coolant temperature"

5.7ute

January 28th, 2014, 12:16 PM

There was a thread on the "other" site, where a simulator was hooked up & the reference point was found to be the end of injection, which in a way makes some sort of sense. This would have the fuel charge always firing onto a closed hot inlet valve, giving time to fully vaporise the fuel charge before the intake valve opened. A large duration cam would have the fuel firing into an open intake valve, causing cylinder wall wash, as well as unvaporised fuel entering the combustion chamber.

Gelf VXR

January 28th, 2014, 06:15 PM

joecar

January 30th, 2014, 04:34 AM

Please pm me the link to that thread.

voda1

January 30th, 2014, 04:47 AM

Links:
http://www.hptuners.com/forum/showthread.php?32510-Injector-Timing-Reference-Periods-refereencing-what
http://www.hptuners.com/forum/showthread.php?12605-When-does-an-injector-quot-turn-on-quot&highlight=injection
http://www.hptuners.com/forum/showthread.php?18549-Please-Help-Define-Injector-Timing

joecar

January 30th, 2014, 05:08 AM

Gelf VXR

February 8th, 2014, 06:56 PM

Looking at the calibrations in the HPT software, I see where the boundary angle of 520 degrees came from (not shown in EfiLive), and in the other forums its said that the boundary 520 - (Normal ECT + Normal RPM) = EOI. For example 520 - (110 + 4.56) = 405.44 BTDC Ignition EOI or 45.44 BTDC for EVC/IVO events, which is where we think it should just be before IVO.

But what happens when the engine is cold, for example 520 - (245 + 4.56) = 270.44 BTDC Ignition EOI or 89.56 ATDC with the inlet valve wide open, which cannot be correct for vaporisation??

If the boundary is 520 degrees BTDC, advancing the SOI and consequentially the EOI, surely the calculation should be 520 + (245 + 4.56) = 769.56 BTDC or 49.56 BTDC of the previous cycle ignition, and so for a hot engine, 520 + (110 + 4.56) = 634.56 BTDC or 85.44 ATDC of the previous cycle ignition, but 270 degrees before TDC EVO/IVO events?

Also, in the HP software the values for Normal ECT and Normal RPM are 50% less than EFI live calibration??

EfiLive show 220 degrees advance at +68 C, HPT shows 110

EfiLive shows 9.13degrees advance at 1150RPM and 185.8 at 4090RPM, HPT shows 4.56 and 92.9

Its not just a case for doubling the boundary value to arrive at EfiLive value (its not visible to check) as the end calculation is not the same?

Why would EfiLive show different values for the same calibration in HPT? All the other calibration data I've compared is the same?

Ive added a diagram I found to more easily identify with SOI EOI events

Gelf VXR

February 9th, 2014, 05:14 PM

Cracked it, well almost, the injector cycle starts 200° BTDC Ignition stroke of the previous cycle, the earliest SOI for the next cycle and finishes 160° ATDC induction stroke of the current cycle, the latest EOI for the current cycle, just before IVC.

But there is still the discrepancy in the calibrations between HPT and EfiLive

Using HPT calibration data at 1150RPM

Calculating advance from 520° ATDC, engine COLD, 520 - (245 + 4.56) = 270.44 ATDC or 89.66 BTDC before EVC/IVO events :)

Calculating advance from 520° ATDC, engine HOT, 520 - (110 + 4.56) = 405.44 ATDC or 45.66 ATDC after EVC/IVO events ?? Injecting IVO explains the fuel smell for positive overlap cams and the success advancing EOI for the EVC?.

Using EfiLive calibration data at 1150RPM

Calculating advance from 520° ATDC, engine COLD, 520 - (490 + 9.13) = 20.87 ATDC Ignition stroke or 339.13 BTDC well before EVC/IVO events ??

Calculating advance from 520° ATDC, engine HOT, 520 - (220 + 9.13) = 290.87 ATDC Ignition stroke or 69.13 BTDC just before EVC/IVO events :)?

More on the boundary angle of 520 degrees, courtesy of Chris HPT.

Boundary is the latest point in time that fuel can make it into the cylinder for the current injection period. It is measured in degrees AFTER TDC compression. It is also the earliest the injector can fire again after the completion of the last injection event. ie. the boundary defines the start/end of a complete injection cycle.

Normal End of Injection Target (EOIT) is the angle before the boundary (in degrees) that the normal pulse (the main pulse) should finish. The hardware calculates the start of injection time from the EOIT and the desired PW.

Makeup End of Injection Target (EOIT) is the angle before the boundary (in degrees) that the first makeup pulse should finish. Makeup pulses are extra pulses that can be injected to inject more fuel during an injection cycle rather than having to wait for the next cycle. There can be more than one makeup pulse but the makeup EOIT specifies the EOIT of the first makeup pulse.

The makeup PW minimum is a minimum PW for the makeup pulses, they cannot be shorter than this (if they are they don't happen).

So you have the boundary that defines the injection cycle, a normal EOIT that specifies the EOIT for the main pulse, and finally a makeup EOIT that specifies the EIOT for any makeup pulses that might be needed if a fuel increase is commanded during an injection cycle but after the main pulse has occurred.

Hope that helps.

Chris...

What is the boundary value for EfiLive and its calculation if it is handled differently HPT?

Highlander

February 9th, 2014, 11:37 PM

joecar

February 10th, 2014, 08:52 AM

He using an LS1B/0411...

joecar

February 10th, 2014, 08:53 AM

Gelf, draw some pictures.

Gelf VXR

February 10th, 2014, 09:20 PM

You are basing your calculations on the e38s?

where does the angle come from? The 0411 ecu uses a reference of time!

In my last post I am referring to Gen 4, all the injector timing data is the same for LS2, LS3 and LS7.

The boundary angle is shown in HPT as 520° (its not shown in EfiLive)

HPT description "Injection Boundary: The latest possible crank angle that the injection pulse can finish for fuel to be delivered to the cylinder"

It does not state TDC, however Chris from HPT noted that "Boundary is the latest point in time that fuel can make it into the cylinder for the current injection period. It is measured in degrees AFTER TDC compression. It is also the earliest the injector can fire again after the completion of the last injection event. ie. the boundary defines the start/end of a complete injection cycle."

Then we have,

{B1205} Injector timing ECT

EfiLive description "This table will offset the actual opening of the injector referenced to engine coolant temperature."

HPT description "Normal EOI target adder vs. ECT: Adds to the normal end of injection target

Advances EOI earlier when cold to allow more time for vaporisation

{B1206} Injector timing RPM

EfiLive description "This table will offset the actual opening of the injector referenced to RPM."

HPT description "Normal EOI target adder vs. RPM: The target angle before the boundary that the normal injection pulse should finish"

Advances EOI earlier to compensate for less time per crank angel degree rotation to allow more time for vaporisation

For Gen 3, the LS1

The boundary angle is shown in HPT as 6.5 ATDC (its not shown in EfiLive)

HPT description "Injection Boundary: Fuel injection delivery boundary as a number of reference periods after TDC"

From Bluecat's post http://www.hptuners.com/forum/showthread.php?32107-GenIII-EOI-fuel-timing&p=238797, he confirmed reference period or reference pulse as 90° crank angle

6.5 * 90° = 585° ATDC (65° later than gen 4, very close to IVC)

Then we have

{B3702} Injector Timing There is no RPM adjustment for the gen 3.

EfiLive description "This table will offset the actual opening of the injector referenced to the reference pulses and engine coolant temperature."

And here's one confusion I think, the table axis in EfiLive shows mS, does this mean Milliseconds?, its reference pulses as per the description. (If you check {B4003} or {B4004} the IPW table axis its shows Milliseconds not mS)

HPT description "Normal injection target vs. ECT. The end of injection target measured in reference periods after the injection boundary that the normal injection should finish"

And here's another confusion, for the gen 4, the target angle is before the boundary, advancing EOI. For gen 3 it states measured in reference periods after the injection boundary that the normal injection should finish. The target angle is after the boundary.

From Bluecat's post I've seen -784 + ((Boundary + Normal) * 90) = -784 + ((6.5 + 5.55) * 90) = 300.5 ATDC EOI, as it fits best with the simulated results.

I think if EOI is to be calculated from the calibration data it should be as follows, the boundary is defined 6.5 * 90 = 585 ATDC or 135 BTDC compression/ignition, the start and end of the injection cycle. Then as per the description "The end of injection target measured in reference periods after the injection boundary that the normal injection should finish"

So EOI is 5.55 * 90 = 499.5° after the boundary ST/END which is 135° BTDC. 499.5 - 135 = 364.5 ATDC or 4.5° ATDC as EVC & IVO, but is 64° later than Bluecat's findings?

What really interesting thou is if you substitute gen 3 start/end of injection cycle with gen 4 start/end of injection cycle value, 135 to 200

499.5 - 200 = 299.5

Its 1° difference

Gelf VXR

February 11th, 2014, 03:06 AM

Gelf, draw some pictures.

Some excel sheet screen shots for SOI and EOI for 2ms, 5ms, 10ms and 15ms IPW. High light green the inlet is open, high light red the exhaust valve is open, its stock LS2 cam events so there is no overlap.

What you can observe is that on a hot engine at low rpm, and low IPW, the injectors are opening and closing on an open inlet valve. In cold conditions and/or higher rpm, SOI and EOI happens while EVO, at very high RPM SOI is before EVO, EOI is while EVO

Gelf VXR

February 11th, 2014, 02:52 PM

I've made a spread sheet for both gen 3 & 4 to show SOI and EOI vs RPM, ECT and IPW. It doesn't seem to want to upload, a couple of screen shots attached

edit, added gen 4 with efilive ECT and RPM data, now looks similar to gen 3

Gelf VXR

February 12th, 2014, 06:35 PM

Because of the differences between the gen 4 calibrations between EfiLive and HPT, I'm going to jump to some conclusions.

I think HPT gen 4 calibration data for injector timing is suspect, here's why

The gen 3 calibrations are the same in both EfiLive and HPT, however the boundary isn't shown in efilive, but it seems logical that 585ATDC would be acceptable as per the description "Boundary is the latest point in time that fuel can make it into the cylinder for the current injection period. It is measured in degrees AFTER TDC compression. Which would be as the inlet valve closes.

Stock IVC ATDC compression for

LS1 = 581.5, later 580.5
LS2 = 582
LS3 = 583
LS6 = 582, later 583
LS7 = 588

All around 585° (the boundary could be modified to cams exact IVC, at 0.05")

If I ignore the 520° boundary in HPT gen 4 and use 585° as the boundary and use EfiLive gen 4 calibration data, the results are practically the same SOI and EOI as the gen 3, apart from EOI advances with RPM in the gen 4 as expected because gen 3 does not have provision for RPM advance.

When the engine is up to temperature, both tables show EOI 365° ATDC compression

Stock IV0 ATDC compression for

LS1 = 375, later 373.5
LS2 = 378
LS3 = 379
LS6 = 378, later 379
LS7 = 378

EOI is just before the IVO (the Normal advance vs ECT could be modified for new cams earlier IVO, EVC is irrelevant if EOI is before IVO with regard to overlap and fuel out the exhaust valve)

It reasonable to assume that GM would stick to similar values across all the platforms? Correction, although the LS1 boundary is 585°, it has been shown to start from 65BTDC which means the boundary is the same gen 4 at 520° ATDC
Tables attached for comparison

joecar

February 13th, 2014, 09:33 AM

I'm slowly digesting this (I'm drawing myself sketches to relate to valve events).

PRAY

March 19th, 2014, 05:13 AM

Any more on this? I think I have the ECT table figured B1205 (I have to add to it for my larger cam) but my RPM table B1206 is populated with zero's and only goes to 4,096 rpm. Would I subtract from zero to shorten the IPW or just do that with IPW to ensure the injection is complete before the overlap period happens? Do they both need to be adjusted to ensure the SOI and EOI only happen on a closed intake valve after the compression stroke? I am dealing with 10* overlap in a LS2. I want to stop the fuel from going out the exhaust valve at idle and low rpm cruise.

Gelf VXR

March 20th, 2014, 11:03 AM

Is it a stock E40 tune or tuners file? If it was me, I would start by copy and paste the stock values for B1205 and B1206. Leave B1206 as is, calculate the difference between IVO from the stock to your new cam profile, assuming the new cam opens earlier, subtract the difference value from B1205. EOI earlier as the IVO is earlier.

I think the B1206 only goes up to 4096rpm as above that SOI maybe around the start of injection boundary, when that point is reached, the EOI has to happen later when the inlet is still open.

Gelf VXR

March 20th, 2014, 11:08 AM

Sorry, add the difference to B1205 like you said

PRAY

March 20th, 2014, 11:36 PM

Thanks for the reply. I have an E67 ECM. Does that make a difference with the technique. I have been tuning the truck my self so all the IPW, Injector timing and Dynamics are still stock. I have actually tuned about 60 cars from stock to 575rw N/A up to 850rw S/C Vettes but have never delved into the injector timing, injector tables or the Dynamics tables. I have been doing a lot of reading on these topics as of late. Since all of the cars in the past have all run really well I thought through all of the fuel and timing calibrating the rest was taking care of it's self. Boy was I wrong. I have a lot to learn and am doing my best to do so. Unfortunately tuning is solely a part time thing. I have often wondered about pump shot and injection timing but rarely get the time to mess with it. I didn't want to hurt what was working. But now learning all of this has lead me to the belief that if the injector timing is off then all of your fueling calibrations will be off also since you are essentially putting a band aid on the actual problem.

Back on topic. From my summation. I take all the original valve events from the stock cam, compare them to the values of the new cam in crank degrees and come up with the difference of where the new intake valve opens vs where the old intake valve opened. I am assuming that will be in degrees of crank rotation of do I do that off of a percentage. The measurement of cam events also has me a little confused. Am I using at .002", .006" or .050" to derive my math? That will lead me to adjusting B1205 and B1206 in actual degrees or a percentage added to the base numbers. I also have to do that for where the new exhaust valve closes vs. the stock exhaust valve to account for the overlap period. Once I have figured those out, I add the difference to B1205 to open the injector earlier in the crank cycle for the intake valve and subtract from B1206 for the new exhaust closing point to avoid the overlap period. That will account for the injector firing on the intake valve after it is closed on the compression stroke/power stroke to avoid fuel being sucked out of the exhaust valve during overlap. Is that right? I see where B1205 is calculated in degrees and I think B1206 is the same but I will have to go back and look at it. I hope that made sense. I am a soldier by trade, not an engineer. Thanks.

BTW, here are my cam specs at .050". LSL 227/235 .617/.621 110+4.

Also, what table represents injection boundary?

joecar

March 21st, 2014, 03:09 AM

So IVC is the event that injector timing precedes...?

( yes, I'm learning a lot )

It appears that EFILive does not expose a table for injection boundary.

Gelf VXR

March 21st, 2014, 06:41 PM

Hi PRAY,

For example I think I am correct in saying, stock IVO 18ATDC, new IVO 18BTDC, difference is 36 crank degrees, add 36 to all values in B1205. The values are crank degrees advance, before the boundary.

I've not looked that closely at an E67, my laptops under repair so i can't look now, it's strange B1206 is all zeros, I'm sure for all the different PCMs I looked after the Ls1, these two tables were all identical and populated?

Hi joe

IVC event is the boundary, 585 ATDC, confirmed for gen 3, 99% sure it's the same for the E40 gen 4, based on my previous tables posted above.

Gen 4 infector timing calculated before the boundary and gen 3 calculated after the boundary.

Edited to correct valve events IVO, not EVC, too much to drink last night :)

Gelf VXR

March 21st, 2014, 08:00 PM

0.050" lift events

PRAY

March 21st, 2014, 09:24 PM

Thanks. As I look at the way a four cycle engine works it seems to me to avoid the fuel going out of the exhaust valve during overlap you have to wait to start injecting fuel till after the exhaust valve closes. Using this thought pattern you will have to figure out the new crank degrees for that event and adjust your IPW to match the new time that the exhaust valve is closed before the intake valve opens. That would also lead you to your new injector timing. But, with a cam with overlap, there is no time that the exhaust and intake valve are not open together during the exhaust stroke before the intake stroke starts. So now I am just confused. Mathematically, there is no way to not loose fuel out of the exhaust during the overlap period unless you start the injection timing once the intake valve starts to open. So, do we just adjust for the new intake valve opening period and live with the loss out the exhaust valve or wait a couple degrees and just start spraying fuel down an open intake valve? I though the whole point of this exercise was to clean up idle and part throttle by hitting the back of the intake valve after the exhaust valve closes for best atomization before the intake stroke happens. Kind of looks impossible now.

Here are the events that I came up with last night using the Wallace racing calculators. According to the stock LS2 cam card I am off a couple degrees for the stock cam but if you do the math that is the only way it works out. So I used the calculator for the stock cam and my new cam. I am not sure what is going on here.

Ls2 cam @ .050” 204/211 .525/.525 116-2 -24.5* Overlap
IVO 16* ATDC + 360* = 376*
IVC 40* ABDC + 540* = 580*
EVO 39.5*BBDC - 180* = 140.5*
EVC -8.5* BTDC - 360* = 351.5*

IVC-IVO = 580-376 = 204
EVC-EVO = 351.5-140.5 = 211
(IVO+IVC)/2 = 478 = (478-360 = 106) 118 ICL
(EVO+EVC)/2 = 246 = (360-246= 114) = 114 ECL
118+114 /2 = 116 LSA and the 118ICL makes it -2 retarded

My cam @ .050” 227/235 .617/.621 110+4 11* Overlap
IVO 7.5* BTDC - 360* = 352.5*
IVC 39.5* ABDC + 540* = 579.5*
EVO 51.5* BBDC - 180* = 128.5*
EVC 3.5* ATDC + 360* = 363.5*

IVC-IVO = 579.5-352.5 = 227
EVC-EVO = 363.5-128.5 = 235
(IVO+IVC)/2 = 466 = (466-360 = 106) 106 ICL
(EVO+EVC)/2 = 246 = (360-246= 114) = 114 ECL
106+114 /2 = 110 LSA and the 106ICL makes it +4 advanced

So 16*+7.5*=23.5* rounded up to 24* or 376*-352.5*= 24.5* rounded down to 24* that I have to add to B1205 to get my new IVO table. B1206 is populated with 0 in my stock tune. I will see if I can find out on the TBSS forum what others have populated in their stock tunes. On the other vehicle tunes I have B1206 is populated but with different data. LS1 being inverse scaled of LS2.

PRAY

March 21st, 2014, 09:42 PM

Something just hit me, if the injector timing stays stock then with a new cam with an earlier opening time and closing time (which mine does not have an earlier closing time, WTF) you are essentially spraying fuel on a closed intake valve. That fuel would get trapped in the runner and would be sent out of the exhaust valve when it opened again during the overlap period. That would result in unburnt fuel exiting the exhaust and causing false WB02 readings. Rich or lean I am not sure of. But that could lead to a lean condition in your cylinder on the intake stroke from late injection fueling that would be masked at the WB02 on the exhaust stroke due to the extra unburnt fuel. So you would essentially be running lean and not knowing it. That would lead to shorter IPW sequences making up for the perceived rich condition therefor expounding on your leanness. If the inverse is true that unburnt fuel makes the WB02 read lean then the IPW will increase creating more fuel being injected after the intake valve closes causing a even leaner reading. So, late injector timing is actually very dangerous? To me, best case scenario now is to find the happy medium where you are injecting fuel as early as possible as the intake valve is opening during overlap. Using a little of the exhaust stream to help fill the cylinder with as much fuel as possible with out leaving any left over to sit in the runner before the exhaust valve opens and dumps raw fuel during the overlap period. Am I making any sense?

Gelf VXR

March 22nd, 2014, 07:42 PM

I corrected my previous post, IVO not IVC.

EOI happens just before the inlet valve opens at normal operating temps, fuel is vaporised before IVO. When cold EOI is advanced earlier to allow more time for vapouristion. As RPM and IPW increases, SOI approaches the boundary, when it reaches the boundary, EOI has to happen later after IVO and during overlap.

PRAY

March 22nd, 2014, 11:36 PM

It makes sense now. I had to pull up some diagrams of valve events in a 360* circle and study those to get it all straight in my head. I added 24* across the board to my B1205 table to account for the difference in IVO between the stock cam and my cam and imported the stock tables to B1206 from every other car that I have with an E40 or E67 ECM like you suggested. It seems that at idle the tables are 0 and from there they taper up to 185* at 4,094 rpm to compensate for crank or piston speed. Still haven't figured out why my B1206 table is populated with 0. The only part of the equation I am missing now is where the 490*-220* calculations are derived from in B1205. They don't match up to the at .050" cam degrees. My thought is that maybe it is calculated off of the .002" or .006" cam degrees. I still think the extra fumes at idle are from EOIT happening after the IVC point and that fuel sitting there waiting for overlap to occur somewhere near TCD. Once the piston begins to travel down word after TDC the vacuum from that begins to pull in the new fresh atomized charge. Thanks for the help. I won't be home for another month to test any of this but I will let you know how it turns out when I get it all done.

Gelf VXR

March 23rd, 2014, 03:17 PM

B1205 & 1206 advance EOI back from the boundary, the boundary is 585 degrees after top dead centre on the power stoke.

The calculation for stock

585-490=95 when cold, which is 95ATDC during the power stroke, an extra 270 degrees of duration required for cold vaporisation

585-220=365 when hot, which 5ATDC induction stroke, 13 degrees before IVO at 18ATDC

PRAY

March 23rd, 2014, 06:24 PM

Thanks, that sheds a lot of light on it. So since I added 24* to the whole table to account for the new IVO point there will still be the same amount of vaporization time but it will be geared to my cam now. I guess next will be adjusting IPW to get it to stop the EOIT just as IVC happens so there isn't any wasted fuel in the runner. I also need to plan my B1205/6 adjustments off of the EVC event to find the happy medium of when the exhaust valve is open during overlap and where the piston stalls at TDC to not waste any fuel there either. I know IPW has minimum adjustment tables but its actual duration is calculated by data from the VVE and MAF table settings correct?

PRAY

March 23rd, 2014, 08:01 PM

Now that I am looking closely at all of this. If the tables are defined by EOIT then shouldn't we be doing our calculations off of the IVC event? What controls SOIT? That seems more important to me in my particular situation. My IVC event is almost identical to the stock cam but the IVO event is quite different. I guess moving the EOIT forward will help this situation and extending IPW by adding more fuel will take care of the back end. Assuming you don't run into boundary. I am also assuming that boundary is where the injector will not extend past or open before no matter what.

Gelf VXR

March 23rd, 2014, 11:17 PM

The boundary coincides with IVC event, it's the last point at which fuel can enter the cylinder for the current cycle, and the earliest point for SOI on the next cycle. EFILive doesn't provide the calibration to adjust the boundary, it doesn't really matter as long as you know where it is, your IVC is 580ATDC, 5 degrees earlier than the PCM boundary value. If you adjusted to your cam, it would give you 5 more degrees before EOI would start retarding finishing later after IVO.

The PCM calculates the IPW for airflow from MAF or VE table, it calculates the number of crank degrees required for that IPW, and calculates SOI back from EOI, B1205 and B1206.

The complete SOI to EOI happens before IVO, as IPW and RPM increase, SOI eventually meets the boundary where IVC from the last cycle. EOI has to start extending past IVO still injecting at the beginning of induction into the air stream, at these high loads I imagine cylinder temps are high enough to maintain vaporisation but may not be mixed with the air as efficiently.

Another way to look at it, there are 720 from IVC to next IVC, at above 85% duty cycle, SOI to EOI takes over 612 crank degrees, there is a minimum off time for the injector in between. It's flat on all the time. The purpose to maintain less than 80~85% Duty cycle may well be to ensure EOI before IVO..?

I see where you going injecting after the EVC, IVO, but If you look at your inlet duration 227 minus the overlap 11 degrees, minus the minimum injector off time, you could be down to say 190, it could be OK at idle and low rpm, but how efficient is mixing and vaporisation of homogenous charge?

Injection happens on a closed inlet valve long enough before it opens to allow vaporisation and cooling of the IV. During overlap some vaporised fuel may be lost to the EV, but not raw fuel, if it still smells raw fuel I would experiment and try increase B1205 values to allow more time for vaporisation.

PRAY

March 24th, 2014, 02:51 AM

Thanks a lot for all of your time and explanations. They have been a huge help in understanding this whole process. After my last post I looked up more valve events images and found a great explanation that made perfect since to me. Now I understand where the 585* boundary comes from. http://www.carcraft.com/techarticles/ccrp_9812_secrets_of_camshaft_power/ This helped me visualize it much better and understand what was happening and when. I have been making a cheat sheet with everything we have been talking about and researching. This is going to be a great help in future tuning and is fantastic information I should have already known. I guess what you don't know can hurt you. Now I just need to figure out Dynamics and I should be set. Thanks again for all the help.

Gelf VXR

March 24th, 2014, 11:41 AM

Glad to share :)

joecar

March 24th, 2014, 01:43 PM

I'm re-reading the above and wrapping my head around it...

some 720* diagrams may help.

PRAY

March 24th, 2014, 02:14 PM

Joe, click on the carcraft link in my last post. That is the graphic that explained it the best to me. It really helped me understand where my valve events are happening and why they are labeled the way they are.

Gelf VXR

March 24th, 2014, 05:36 PM

I'm re-reading the above and wrapping my head around it...

some 720* diagrams may help.

It maybe easier to think of it like a 24hr clock.

Cycle starts at midnight, IVO happens at mid day, inlet closes at 8pm, EOI needs to be around 10.30am, 9.5hrs before 8pm.

If your IVO earlier at 11am, you need to advance EOI earlier, 10.5 hrs earlier instead of 9.5hrs, before 8pm.

The boundary is at 8pm.

If it a gen 3, boundary is still 8pm, EOI is at 10.30am the following day, 14.5hrs later or 13.5hrs later if IVO happens at 11.00am instead of 12pm

PRAY

June 6th, 2014, 01:31 AM

UPDATE: Finally made it home and was able to advance the injector timing like we were discussing. I only rolled it forward 24* since that is how far the new intake valve is advanced from the stock cam. So far the smell of the fuel has gone down quite a bit. I had to take out a bunch of fuel at idle because it was pig rich but the rest of the VVE table remained basically the same. I figured the whole fule table would be rich down low but it was only below 1,000rpm. The seat of the pants feel down low is drastic. A bunch more power on tip in and normal driving. The big deal to me is that I gained 3mpg on average over the last four tanks of gas. One thing I haven't been able to do or change yet is the dynamics. There is now a very slight stumble at minimal throttle input. Like backing out of my drive way. It almost acts like I am not moving the throttle when I am to a certain point and then it takes off. There needs to be more effort put into the tune right there. The other thing I noticed is that during cold start up and OL my commanded fuel is static at 13.0 but the WB reads 15.0 now. Any deviations in fueling from 13.0 causes a bit of surging that goes away pretty quickly. These issues could be unrelated to advancing the injector timing but I will work on them and figure it out. Hope this helps anyone that was following along.

voda1

June 10th, 2014, 01:06 AM

So EOI is 5.55 * 90 = 499.5° after the boundary ST/END which is 135° BTDC. 499.5 - 135 = 364.5 ATDC or 4.5° ATDC as EVC & IVO, but is 64° later than Bluecat's findings?

What really interesting thou is if you substitute gen 3 start/end of injection cycle with gen 4 start/end of injection cycle value, 135 to 200

499.5 - 200 = 299.5

Its 1° difference

For early Gen3 the the EOI was 4.77 x 90 = 430 deg, 70 deg. difference than with the 5.55 figure.

Highlander

June 11th, 2014, 04:34 AM

What OS is everyone using... maybe I will release my cax were ido have the injection boundary in efilive...

16979

Gelf Send me your email via PM to email it to you.

PRAY

June 11th, 2014, 05:23 AM

I am running OS 12611938. I have an 07' TBSS running an E67 ECM. I don't have the table you do.

Highlander

June 11th, 2014, 05:39 AM

Because this is for a GEN 3.... you don´t need that parameter.

PRAY

June 11th, 2014, 08:18 AM

Gotcha.

Gelf VXR

June 11th, 2014, 10:20 AM

What OS is everyone using... maybe I will release my cax were ido have the injection boundary in efilive...

16979

Gelf Send me your email via PM to email it to you.

PM sent, I'm using a gen 4 E40

Highlander

June 11th, 2014, 11:04 AM

E40 doesn't have this value....

joecar

June 11th, 2014, 03:41 PM

What OS is everyone using... maybe I will release my cax were ido have the injection boundary in efilive...

...12212156.

Highlander

June 11th, 2014, 04:14 PM

0202005 which is the same....

Gelf VXR

June 11th, 2014, 04:27 PM

I was hoping you had something to view the calibration for the gen 4.

We can live without boundary adjustment in efilive as long as we know where it is, I would think you would only need to adjust if your IPW was maxing out (SOI approaching the boundary) and or your cam IVC was was a lot later than 585ATDC.

Highlander

June 11th, 2014, 06:21 PM

What do you mean view the calibration??? on gen IV there is everything we need to actually calibrate this properly....

Highlander

June 11th, 2014, 06:23 PM

You guys need the boundary for the E40?

Gelf VXR

June 11th, 2014, 07:31 PM

You guys need the boundary for the E40?

You can not view or adjust the boundary in efilive for e40 or e38

joecar

June 12th, 2014, 12:54 PM

02020005 which is the same....Yes, this is what I'm actually running.

:)

picnic_george

June 15th, 2014, 07:08 AM

All this info is above my pay grade. Is there a magical number to adjust the setting(s) to when you know your cam intake valve is openning xx degrees earlier than the stock camshaft?

Gelf VXR

June 15th, 2014, 05:00 PM

picnic_george

June 16th, 2014, 04:18 AM

No,.. just that :)It would seem that with overlap people are having better luck delaying the injector as to eliminate it going out the exhaust valve if I have read that correct. This is acheived by increasing the value in B3702, correct??

joecar

June 16th, 2014, 04:39 AM

All this info is above my pay grade. Is there a magical number to adjust the setting(s) to when you know your cam intake valve is openning xx degrees earlier than the stock camshaft?

No,.. just that https://forum.efilive.com/images/smilies/smile.png

Except for LS1 it is in ms rather than degrees... requires some external math to convert between ms and degrees.

picnic_george

June 16th, 2014, 04:54 AM

I'll get a grasp around the mathematical equation eventually. I'm just trying to understand that raising the value delays the injection cycle and people have(generally) seen smoother idle and less fuel smell with overlapping cams. Due to not sucking unburned fuel out of the exhaust, even though GM designed it to spray on a closed intake valve to help atomization(which it will no longer do). I'm still doing a lot of reading and some of the numbers seem awkward to me, but I'm pretty good with numbers so I'll get it lolol

Thanks

Gelf VXR

June 16th, 2014, 11:06 AM

Unless your IJC is maxed out, start to end of injection happens while that inlet is closed, and some time before it opens to allow for vaporization, with a high overlap cam I would try advance far enough so vapor rather than raw fuel can be drawn into the exhaust.

It's theoretically possible to have the injection event after EVC, it doesn't for much duration before IVC, and only when at running temperature, not a very efficient burn

picnic_george

June 18th, 2014, 01:43 AM

joecar

June 18th, 2014, 03:52 AM

IJC ---> I think Gelf meant IDC (as in INJ DC).

Gelf VXR

June 18th, 2014, 08:23 PM

What's IJC?

From what I've been reading it seems like people have been having luck delaying the injector some(til the tail end of the EVC events and not paying too much attention to the IVO events). Too early you suck fuel out the exhaust valve, too late and you can't use the exhaust to help draw the fuel in. Granted that happening eliminates the fuel hitting the closed intake valve. I guess I should have joined the discussion a few years ago lolol

Thanks

My bad i meant IDC, thanks Joe.

You have to remember the calibration is for the end of injection EOI, SOI is calculated in advance from EOI depending on pulse width, so SOI happen after EVC, you need to retard EOI well into the induction stroke. If your running closed loop idle, a poor homogenous charge surely will play havoc with O2 sensors, keep adding fuel if O2 reads lean because the unused O2 in the combustion.

I don't have a high overlap cam so I have not tried for myself so I could be wrong :)

PRAY

June 18th, 2014, 09:00 PM

I made a sheet that explains all the math because I had to spell it all out the long way before I understood it. What it boils down to is you need to add to the injector timing table how ever many degrees the IVO of your new cam is over/before your stock cam and play with it from there. So, stock cam opens at 16* ATDC and new cam opens at 8* BTDC then you add 24 to your injector timing table. I also noticed in my particular tune that there was no advance in Timing vs. RPM. All the other cars I found had some. So I copied and pasted to see what would happen. It seems to be working.

joecar

June 19th, 2014, 04:19 AM

PRAY

June 19th, 2014, 07:18 AM

I suck at posting pics and what not on the net. Can I email it to you? It is all of the notes I have made and the math that goes with it for this subject on a word document.

PRAY

June 23rd, 2014, 11:17 AM

Hey Joe,

Did you get my email?

joecar

June 24th, 2014, 07:32 AM

I'll check my email...

PRAY

June 24th, 2014, 08:47 AM

Okay, I sent you what you asked for last week.

joecar

June 24th, 2014, 11:16 AM

I don't see any emails that might be from you (not in my inbox nor in my junk/spam folder).

PRAY

June 24th, 2014, 12:21 PM

Okay, I will resend. It would have come from Ber1tuning@gmail.

joecar

June 25th, 2014, 09:27 AM

Ok, I'll look out for it.

joecar

June 25th, 2014, 10:03 AM

I did not see email from you... so I sent you an email using the email address you showed in post #143 above (with .com on the end of it).

Gelf VXR

July 3rd, 2014, 09:40 AM

ting research paper of injector timing, open inlet valve vs closed inlet valve injection

http://www.v-eight.com/multimedia/library/Effects%20ofinjection%20timing%20on%20exhaust%20em issions%20of%20a%20fuel%20injected%20spark%20ignit ion%20engine.pdf

"However, one can speculate from these trends that the effects of injection timing on mixture quality are the reason for differences in CO emissions. Since the CO is formed due to a lack of oxygen present to make CO2, a better mixture quality is essential to lowering the CO emissions. From already stated reports dealing with HC formations, it was found that OVI injection timing can cause a local stratified mixture in the cylinder, which would cause more CO emissions due to locally rich regions in the cylinder. Conversely, with CVI timing, the fuel is transported completely through atomization. Thus, less fuel becomes stuck near the cylinder wall, causing a more homogeneous mixture. At low speed, gas temperatures and air velocities are lower than for the high RPM case. At low load, the gas temperatures are less hot than at high load. Therefore, changing from low load/speed to high load/speed has an effect on fuel/air mixing properties. However, it can be speculated that the differences in mixture quality between OVI and CVI timing become smaller as speed/load are increased. The high temperatures in the cylinder help the fuel on the cylinder wall vaporize, and the high velocities will help the fuel mix with the air more effectively during OVI timing. Once these conditions were combined, such as in the case of high load and high rpm, the data actually showed a small increase in CO emissions for the CVI timing case.
Injection timing also had a significant effect on hydrocarbon emissions at low engine speeds. This is illustrated in Figure 6. In all cases at 2100 RPM, negligible differences in hydrocarbon SE were observed. However, at 1500 RPM marked differences were detected. Stoichiometric conditions were affected the most by injection timing. For instance, the HC specific emissions (with φ=1) decreased approximately 30% at both load conditions. At lean conditions, the HC SE decreased 16% and 25% at loads of 200 kPa and 400 kPa, respectively. These results coincide with the findings of Arcoumanis et al [8] and Yang et al [4]. These changes occur for many of the same reasons mentioned in regards to CO emissions. The larger number of fuel droplets as well as the higher concentration of fuel near the cylinder wall from OVI timing decreases combustion quality, maximizing HC emissions. Once again, as shown in the CO data, the higher engine speed/temperatures at 2100 RPM quash all benefits inherent in CVI timing."

Highlander

August 22nd, 2014, 05:57 PM

All the calculations around the net about the low resolution periods is INCORRECT! Lo Res periods is NOT 90 degrees.

statesman

August 23rd, 2014, 12:10 AM

All the calculations around the net about the low resolution periods is INCORRECT! Lo Res periods is NOT 90 degrees.

If it's not 90 degrees, then what is it?

Gelf VXR

August 25th, 2014, 02:26 AM

+1^^^

5.7ute

August 25th, 2014, 12:14 PM

My thoughts would be a low res period of 720 degrees, hi res period of 6 degrees. Low res being the cam sensor which is a single pulse per cam revolution, Hi res from the crank reluctor which has 58 teeth, but is actually 60 minus 2 in the spacing.

picnic_george

August 26th, 2014, 01:33 AM

Don't all gen 3 engines have a 24x reluctor though? And if not all, most for sure.

5.7ute

August 26th, 2014, 09:22 AM

Don't all gen 3 engines have a 24x reluctor though? And if not all, most for sure.

Correct. I had a blonde moment.
That would put the hi res pulses at 15 degrees.

joecar

August 26th, 2014, 08:27 PM

If the hi res pulses are 15 degrees apart, how many degrees between the lo res pulses (90 as highlander said...?)...?

Highlander

August 27th, 2014, 02:12 AM

low pulse is not 90 degrees apart.

5.7ute

August 27th, 2014, 12:31 PM

Going from the waveforms in the manual, the cam sensor pulse runs on for 360 degree crank rotation, off for 360 degrees. So 360 apart. The crank uses a mix of 12 & 3 degree pulses at 15 degree intervals.

Gelf VXR

August 27th, 2014, 02:36 PM

low pulse is not 90 degrees apart.

What do you think it is?

On the other forum the pulse degree angle and checked on some apparatus and confirmed it is 90 degrees, was he wrong?

http://www.hptuners.com/forum/showthread.php?32107-GenIII-EOI-fuel-timing

Highlander

August 27th, 2014, 02:40 PM

No... the pulse might be 90 degrees apart, i just misunderstood what it meant.. but the pulse is 65 degrees before top dead center....

So the calculations have to be made in base of that information.... it doesn't matter what they are apart.
I don't have the equipment to test, but a simple calculation yields a very similar result if you use 784 and 90 degrees or if you use 720 and 65 degrees.

If you have 65 degrees before top dead center, and you have certain amount of periods, it means 65 x Lo Res Periods... so it makes no sense for the ECU to have specified this angle in the calibration and have it use 90 degrees since they are apart.

Highlander

August 27th, 2014, 02:45 PM

The other problem is ... we don't exactly know when the ECU is actually asking for pulse after the boundary.... it can shoot the injector before the boundary and after if it needs to. My guess is that if conditions change after the calculation, then it does fire afterwards. If we don't know what that criteria is and how to control it, my guess is that we are still chasing our tails.

Tre-Cool

October 27th, 2014, 02:02 AM

Been looking into this lately for my own car and found a couple of good threads over on hptuners forum. this post below is the standout on how it all works.

To put it into context, the whole thing is about vaporization of fuel in a stock setup, and about not throwing out fuel on the cammed up side.

In a stock rig, the injector sprays onto the back side of an intake valve. Both valves are in contact with the heat from the combustion chamber, but only one valve ever looks like it's been hot, right? That's largely because the intake valve is being cooled off with fuel, and nothing cools the exhaust valve directly.

In stock form, it's about turning raw gasoline (liquid) into burnable vapors (gas). Raw liquid gas doesn't burn, only the vapors do. So we use an injector at 58 psi to turn big gulps of liquid fuel into small droplets of gas. EFI and it's high pressures do this wonderfully to begin with, compared to the raindrops of fuel coming out the bottom side of a carb, right?

Then we spray this fine mist in a cone pattern onto the back side of the intake valve, and we shape the cone to hit near the edge of the valve, by the seat. This way it cools off the hot sharp edge of the valve, and as the valve opens, the air flowing in tends to shear the droplets into even smaller droplets.

Since the cool fuel hits the hot valve, it tends to vaporize and become a gas. So picture it in your head. The intake valve is closed, the motor is idling, the injector PW is maybe 2 - 4 milliseconds at idle, and the injector delay table is programmed to spray onto the valve just before it opens. This way, other cylinders going up and down don't inadvertently steal the air and fuel vapors out of this intake runner.

The injector will have a start time and an end time. The delay table back-calculates the injection timing. So let's say the intake valve is going to open at X degrees of crank rotation in the engine cycle, and the engine is idling so it only needs 3 ms of pulsewidth. The injector would END its spray pattern just before X degrees rolls around. So it would have to START it's spray pattern at 3 ms before X in order to finish by X. If the pulsewidth jumps up to say 15 ms at WOT, then the injector would finish by X still, but start at 15 ms before X.

Here's where it gets interesting. You can calculate the engine speed, the 720 degrees of crankshaft rotation (the cam runs at 1/2 the speed of the crank), and you can figure out exactly how many milliseconds (ms) of time becomes how many degrees of crankshaft rotation. That's just math. So if you're only idling, that start and end of injection time (SOIT and EOIT) will be very close to the time when the intake valve is about to open.

So picture the closed intake valve, the injector opens for a few ms before the intake valve opens, and it closes just before the intake valve opens, making sure that fuel is now vaporized, broke up into little bity pieces, and basically a gas cloud at this point. Then the intake valve opens, that gas cloud immediately gets sucked into the cylinder, and it's ready to be exploded.

Now picture a cam change. We have a cam with a lot of overlap (because it sounds cool at the local drive-in). The intake valve and exhaust valve are now open at the same time, in a way the factory never intended. The intake manifold has vacuum in it (at this point, that vacuum is coming from the other cylinders!), so the intake runner is in a state of low pressure - vacuum. The exhaust system on the other hand, has high pressure in it, from those other cylinders firing and trying to get out thru a small pipe, causing some backpressure.

Now both valves are open at the same time, so the high pressure goes towards the low pressure. That means the exhaust goes in the exhaust port backwards, goes thru the combustion chamber, and exits out the intake port. It pushes some of this nice vaporized fuel cloud backwards, up into the intake manifold. (This is called reversion or standoff in carb speak). But that doesn't last long, and then it reverses direction and the intake charge now gets sucked out the exhaust valve instead.

But our computer calculated just the right amount of fuel, no extra. So we can't afford to lose any fuel out the exhaust valve, or the cylinder runs lean. So we end up richening up idle to compensate for the lost fuel. This is why cammed up cars like to be richened up at idle and low speeds.

We could move the injection timing back some, so that we don't inject fuel into a valve that has already opened. And that might be good, if we have a longer duration cam than stock, but we don't really have any more overlap. So maybe for a mild cam, that works well.

But if we move EOIT back like that, we make it more likely that the other cylinders steal fuel from our intake port. We also still have the problem that as soon as the intake valve opens, some of that fuel is going to go right out the exhaust anyway.

So if the cam is pretty big, we go the opposite way of common sense. We inject the fuel later, onto the back side of an intake valve that's already opened. Why? Well, with longer duration, we can't start the injection any earlier, or we'll end up injecting on the previous engine cycle, where the valve is still open from the last time. So we're going to lose some of that fuel vaporization by doing this, but we are going to be able to time the injection more properly to the longer duration cam.

We're also not building up that cloud of fuel, just so it can easily get pushed back up the intake, or straight out the exhaust, as soon as the valve opens. Better that we spray it in as we go, instead of 'building it up just to get stolen' all at once.

On here, guys are trying to time the injection so that the exhaust valve has already closed. So that means a few degrees after TDC, instead of a few degrees before TDC for EOIT to happen. But what I think is being overlooked is the fact that at WOT, the injector duty cycle is supposed to be roughly 80%, right? So the injector is open 80% of the entire 720 degrees of crankshaft rotation. Which means it must START long before the intake valve opens, and end long after the exhaust valve closes.

Because of this, I theorize that it's not really about the exhaust valve open/close points, as much as it is about starting the injection at the right time (to match the new cam opening/closing points), and about not having the cloud of fuel stolen or completely evacuated out the exhaust valve.

More common thinking is that it's only about the overlap period, and losing so much fuel out the exhaust, and not so much about having fuel stolen from the intake runner by other cylinders (or pushed back up the intake by exhaust pulses during overlap).

At higher speeds, all this stuff sort of works itself out. But at lower engine speeds, the overlap may be the exact same amount of crankshaft degrees, BUT the amount of actual time it takes to pass thru those degrees (a product of RPM) is much longer. So it's sort of like trying to play ping pong in slow motion. It just don't work.

My best guess about what to do here is to experiment with EOIT by slowly adding to it, making the injector start and end it's on-time later in the engine cycle. (Unless you have a mild cam, then maybe go the other direction). I would start by adding 10 degrees of delay at a time, and monitor the results. If you are improving the situation, you'll notice that the engine is getting richer on the wideband.

This is because the correct cylinder is actually GETTING the fuel you injected for it. So an increase in a/f ratio is an indicator that you're improving your situation. Obviously, you'll end up going back to your airflow model and leaning the car out to compensate eventually.

If it liked 10, add another 10 and see what happens. It's tough to say exactly how much a motor would like, since all cam overlap periods are going to be different. But somewhere between 20 and 40 extra degrees sounds about right.

The LS1 PCM doesn't go by actual crankshaft degrees in their delay table though. They go by reference periods. Each reference period is 90 degrees. So if you want to add in 10 degrees, you would add .11 reference periods. Also noteworthy, some clever fellow on here decided to take an engine on the stand, and test it to see where the 720 degree cycle actually starts at, and found that it started at -784 (if I remember correctly). That's just about where the cam sensor is relative to actual TDC on #1, and about actually sensing the crank magnet go by BEFORE the cycle starts, so the PCM has time to get it's act together by the time the cycle actually starts.

That's unimportant if you're just going to add 10 degrees at a time until the motor doesn't reward you any further. But it is important, if you have drawn up a 4 cycle chart on paper, and are trying to actually calculate when the injection timing is going to end, compared to when your cam valve open/close points happen.

And just when you think you've got it all mastered... "did you degree the cam in, and has the chain stretched any since?". heheh

It's not rocket science. Just add a little delay in at a time to the normal table, and probably leave everything else alone. I am a bit less informed of exactly how the makeup thing works, but I'm sure it's about the same way. I believe makeup is made up of things like acceleration enrichment and other last-minute changes to fueling, while normal is the typical fuel injection cycle.

This now begs the question, when can we get the injection timing boundary value into efilive for the custom os5's. we only have the injection timing and injection timing trim, there is another single value data point for the boundary.

joecar

October 27th, 2014, 01:19 PM

Thanks for the quote.

It seems that SOIT/EOIT is important at low engine speed, and that it becomes irrelevant at higher speeds
(for example, 80% INJDC spans a 576* out of the 720* cycle, and at 6000 RPM 720* is only 20 ms).

Mud

January 27th, 2015, 09:49 AM

Interesting thread, thanks to all involved. I am on LS1B COS2 (01290002), so only have B3702 (and B3703) to play with. Conversation seems to have centred on later OSs with B120x (for understandable reasons), but is anyone able to confirm the LS1B tables are indeed in reference pulses (mS vs. milliseconds) as Gelf postulated back on page 9? This seems to tally up with the HPT people, and the 5.55 number that keeps cropping up. It also seems a better (more apt) unit than milliseconds.

For the stock LS1 (2004 Monaro) cam I have:
IVO IVC EVO EVC
377.5 574.5 140.5 347.5

And my cam:
361 583 129 355

So I assume if I want to set injector end to IVO, I want to advance 16.5 degrees, so subtract 0.183 from B3702. If anyone could sanity-check it would be a great help :)

Gelf VXR

January 28th, 2015, 06:27 PM

I think it's correct, subtracting 0.183 advanced EOI 17 degrees in my spread sheet calculator, I'll post it later

PRAY

February 24th, 2015, 03:43 PM

After reading all of this again, especially the logic of the quoted section on the previous page, are we advancing the Injector timing or retarding it from 490-220 in the E67? I have a much larger cam now in a 427. It only opens 3* earlier than my previous cam but now has 21* of overlap instead of the 10* I was dealing with. I can see where with a large overlap period hitting the valve after it opens some could be beneficial. I am having a very hard time leaning out my VVE table far enough to compensate for my -LTFT's which to me says I am running rich not lean. Now I just confused myself. Crap. I am going to have to put it in Open Loop and start messing with just injector timing to see what I get for AFR's. Then I guess go back and adjust everything again to get it back to stoich.

PRAY

April 25th, 2015, 12:35 PM

Here is what I ended up doing and it worked great for my build. I used injector base pulse width at idle vs. my cams seat to seat timing to find my new EOIT. I took out my degree wheel and input the .050" and .002" numbers for my stock cam and my current cam. This was a serious eye opener. The stock cam has -16* of over lap at .050" but 0* at .002". Then I input my cam. It has 21* at .050" and IIRC 73* at .002" This made me realize that I was advancing it no where near far enough to actually get the injector to fire prior to the intake valve opening. The small adjustments I was doing was still firing into an open intake valve since I was using .050" numbers to get my injector advance calculations. Next, I checked my IPW at idle which was 1.85ish ms at 900rpm. That data was invaluable to me. I used it to calculate how long it took my injector to fire in crank degrees which is 10*. I had no way to check how long the stock injector takes to fire. But I can only guess that it was around 20* or so since the stock EOIT is 5*ATDC. So I advanced my EOIT 43*. This put my EOIT right at where my intake valve starts to actually open. My idle and low rpm driving improved substantially. The car doesn't buck above 1,200rpm now. I am also averaging 18mpg and getting around 25mph at 60-70mph on the highway. Mind you this is in my 3.73 geared 07' 4,100lb CTS-V with a LS3 427 with ported LS2 heads, 21* overlap cam, ported stock intake and stock cat back. I am also running 52lb injectors. I will say that I have done a bunch of VVE tuning and my MAF is lined up properly. I don't see much over +/- 2 LTFT's. I still have some work to do in the fueling department and I haven't touched dynamics yet since I don't have a good grasp on it yet.

Mike, wish I could have met you a couple weeks ago when I was down in Atlanta. I stopped by and finally me Ron after eight years of dealings and checked out the shop. I was hoping we would be able to talk some tuning face to face but you were on vacation. Maybe next time.

Highlander

April 25th, 2015, 12:39 PM

PRAY,

My name is Christian, I just happen to work with Mike... :) but i'll send him your regards... And yes... he was on vacation and pretty much NO communication... I think he forgot his name during that week...

PRAY

April 25th, 2015, 12:43 PM

Okay, thanks. Sorry about that, I was confused by the end of your post.

spy2520

September 10th, 2015, 05:45 AM

These spreadsheets...is the injector really firing this early at lower temps? am i reading this right?

Gelf VXR

September 16th, 2015, 11:31 PM

That's the data from the PCM

MSURacing

September 10th, 2016, 04:18 AM

SPY2520
They do this to "Preheat" the fuel on a cold engine. This allows the fuel to evaporate on the back of the valve because it is the warmest thing in the airstream at those temps!!
You also have to remember the amount of fuel that is being commanded at those levels, just look at your Open Loop Fuel and cranking fuel tables.
It's still an engine and if you aren't evaporating the fuel, it has to be done with a larger amount of the mixture.
It also aids in Catalyst light off, low timing, high amounts of fuel, and you make the first thing to be warm!

johnj

November 18th, 2016, 05:03 AM

So i have read through this entire post a couple times now and I am still lost on how the spread sheet actually works. Can someone please help me clear this up?

Sent from my iPhone using Tapatalk

Highlander

December 9th, 2017, 07:53 AM

joecar

December 11th, 2017, 11:10 AM

So here is the way it is calculated...

EOIT is X lo res periods (B3702) after the boundary (which is typically 6.5).
So...... 6.5 x 65 = 422.5 BTDC
Injector fires 5.5 (stock at normal coolant) after the boundary it means 6.5-5.5 = 1 x 65 Lo Res Periods = 65 BTDC.

Hope this helps.
do I read that as "(6.5ms - 5.5ms)*65deg/ms = 65 deg BTDC" ...? I'm not sure where the 65 comes from (and is it deg/ms...?)...?

Highlander

December 12th, 2017, 12:19 AM

I never said its ms.

Its lo res periods. One period = 65 degrees crank. Its a calibratable value.

joecar

December 12th, 2017, 06:16 AM

Ah, lo res periods, not ms, I see, thanks.

spy2520

April 20th, 2018, 02:12 PM

Has there been a consensus on which direction to go with big overlap cams (20*+)? On one hand it looks like the goal is still to put EOT just before IVO. On the other hand there it does seem like a good idea to hold off until closer to EVC.

Millsy

August 22nd, 2018, 01:04 PM

After listening to a pod cast interviewing Greg Banish, basically whatever slope (cold to warm) the factory is using, for cammed cars you continue with the slope. By this i mean the following, for LS1, the slope increases from cold to warm, therefore 'add' numbers. For E38, the slope decreases from cold to warm, so therefore 'subtract' numbers. For mild cams i start with adding 0.5ms to LS1 and subtracting 20* from E38, it's worked well so far for idle and low speed/rpm driveability.

joecar

August 22nd, 2018, 04:00 PM

Thanks for the info.

98SS2836

January 3rd, 2019, 12:32 AM

I think it's correct, subtracting 0.183 advanced EOI 17 degrees in my spread sheet calculator, I'll post it later

I want to understand how to use this spread sheet.

22591

Attached is my cam card.

How do I convert to what ever units I need to convert to?

aaronc7

January 14th, 2019, 08:34 AM

I've been digging back into this lately and notice a discrepancy between the spreadsheet posted in this thread vs others on hptuners. IDK what's right and either way a calculator is only going to get you so close. There's different theories on whether or not it's better to advance the end of injection or delay the end of injection with big cam swaps... I think generally delaying is more well liked based on what I've come across.

Either way, your best bet is to probably do a little trial and error and see what your car likes. I am going to fully warm up the car to keep that variable constant, and then try increasing or decreasing B3702 value in 0.2 increments, datalog idle conditions and see how they look. I'm going to run closed loop, LTFT disabled and look for the setting that gives me lowest fuel trims, i.e. least amount of fuel required to maintain standard 14.7:1 idle. This should translate into what's most efficient for my new injectors, cam timing etc.

I just changed injectors and figured it was good time to dive into this before re-tuning the whole fuel map now. I'm using Deka 80 lb/hr injectors and a B3702 value of 5.35 at operating temp and with reasonable VE table values my fuel trims were +25-30 percent, so something seems off and I want to see the effect that injection timing has before just adding to the VE table. My values were changed to put injection earlier, but now I run a totally different style of injector so the theory of spraying fuel onto a hot valve to evaporate may not work out as well. If I want to delay my injection until after EVC (@ 0.050"), I need a value of ~5.6 or ~6.3 depending on which calculator I want to trust.

If someone has a better technique let me know!

aaronc7

January 15th, 2019, 06:23 PM

Update, I did what I posted above and tried values of 5.55, 5.8, 6.0 and 6.2. Average idle pulsewidth varied by less than 0.005 ms and fuel trims varies less than 0.5%..... made absolutely zero difference.

statesman

January 16th, 2019, 02:53 AM

I've been digging back into this lately and notice a discrepancy between the spreadsheet posted in this thread vs others on hptuners. IDK what's right and either way a calculator is only going to get you so close.

Yes, but when you want to experiment with different values... it helps to know if you're even in the ballpark.

What are your cam specs?

aaronc7

January 16th, 2019, 03:49 AM

statesman

January 16th, 2019, 04:14 AM

226/230 113 +2. IIRC, IVO 357* and EVC 359*. I did use the calcs to get in the ballpark, there is just a discrepancy in the one posted here vs most others on hptuners. Either way I saw virtually no difference in fueling by retarding injection timing by up to ~60* which I find surprising, but it's what the data says.

Yeah, but think about where that ~60* is.

Update, I did what I posted above and tried values of 5.55, 5.8, 6.0 and 6.2.

5.55 is 60*BTDC
6.2 is TDC

Hmmm.... your comparing spraying on a closed valve to spraying on a closed valve. I wonder why it didn't make any difference?

The correct way to calculate EOIT was figured out experimentally by Bluecat about 8yrs ago.

https://forum.hptuners.com/showthread.php?32107-GenIII-EOI-fuel-timing

Enjoy!

aaronc7

January 16th, 2019, 04:20 AM

The calculator actually said I should go to about a ~6.3 value, I guess perhaps I should actually try that as it would be slightly after TDC. I have read that thread and understand the formula. Even in this thread there seems to be some disagreement on the formula and 'reference period', but the bluecat thread was the most conclusive thing I've come acrosss

edit: A value of 6.3 should start the inj pulse at 360* and end at 368". I'll try values of 6.3, 6.4 and 6.5 and see if it makes any difference

statesman

January 16th, 2019, 04:41 AM

Even in this thread there seems to be some disagreement on the formula and 'reference period', but the bluecat thread was the most conclusive thing I've come acrosss

Bluecat proved experimentally how injection timing is calculated. I don't understand why some people on this forum have other ideas, but Bluecat's formula is correct... and contrary to what some people on this forum think, a reference pulse is actually 90 degrees. You can use the same principle to calculate Gen4 EOIT. The main differences being that Gen4's use crank degrees and they calculate backwards from the boundary where Gen3's calculate forward from the boundary... and yes, the stock timing is the same for both.

aaronc7

January 16th, 2019, 04:46 AM

Thanks for your comments and thoughts, I'll follow up my little experiment. With these new injectors, I am needing pretty high idle VE values, so I have been digging into injector data to include this timing stuff, before proceeding further.

aaronc7

January 16th, 2019, 05:40 PM

Well, I did the same test for 5.55, 6.2, 6.3 and 6.4. I dialed in my VE table so trims were spot on with the 5.55 settings. I had identical results again across the board for all injector timing values. Average fuel trims varies about a couple tenths of a percent and IBPW by .005 or so on average. Perhaps my cam is just mild enough and does not have have enough overlap to see benefit in this.

statesman

January 17th, 2019, 02:59 PM

Perhaps my cam is just mild enough and does not have have enough overlap to see benefit in this.

That's exactly right.

I can see that you like to experiment and find things out for yourself, rather than just accepting what some random idiot tells you on the internet... which is why I helped you down the path to what might seem like a dead end, but at least now you know how to calculate EOIT and you've proven to yourself that spraying later doesn't have any benefit with your cam.

The real benefit is for pure race cams... and the benefit shows up as a reduction in ET over the 1/4 mile.

aaronc7

January 17th, 2019, 03:03 PM

You are right that I don't like to just accept whatever I read online as fact...actually so much misinformation that just gets parroted and before long everyone is an expert and it's a 'fact'. What's interesting is over on hptuners forums you see plenty of guys who have a cam with similar specs to mine and claim this made a big difference, etc. Maybe faulty test measures, I made sure IAT/coolant/oil temp were as consistent as possible.

Either way, I'm glad to have worked thru this and press on with the tune.

joecar

January 18th, 2019, 10:16 AM

reminder to self: brush up on eoit calc.

aaronc7

January 18th, 2019, 11:00 AM

reminder to self: brush up on eoit calc.

EOIT = 90 * (boundary + B3702) - 784

joecar

January 20th, 2019, 02:52 PM

EOIT = 90 * (boundary + B3702) - 784
That's referenced from TDC at top of compression (spark plug would have just fired), right...?

I'm out of town so I can't easily look in a tune file or in my notes...

where boundary does come from (I'm not going to like the answer)...?

( I'm going to reread this thread and the HPT thread )

aaronc7

January 20th, 2019, 05:00 PM

That's referenced from TDC at top of compression (spark plug would have just fired), right...?

I'm out of town so I can't easily look in a tune file or in my notes...

where boundary does come from (I'm not going to like the answer)...?

( I'm going to reread this thread and the HPT thread )

I simplified the equation, but if you 'write it out' I think it makes more sense. At least it did for me in trying to figure out what the math meant.

EOIT = -784 + 90 * boundary + 90 * B3702

360* would be end of exhaust stroke / start of intake stroke in the valve overlap area.

From what I understand boundary is just a known reference/starting point, separate from the 'injection timing' table. The table is not visible by default on EFI and there isn't a CAX posted on here, but it's out there, apparently. It's in the HPT tables, but obviously you can see that any change to boundary will directly affect the timing, just as B3702 would. I don't think you really need to alter boundary unless you're trying to change the timing significantly.

-784 was just observed to the starting reference point for the calculations (previously linked bluecat thread). So you just start there and work your way back from there based on those 2 values. I don't claim to be an expert or anything on this, just a guy who recently dug into it.

joecar

January 21st, 2019, 05:59 PM

That's referenced from TDC at top of compression (spark plug would have just fired), right...?

360* would be end of exhaust stroke / start of intake stroke in the valve overlap area.

Ah, ok, I see.

joecar

January 21st, 2019, 06:04 PM

...

From what I understand boundary is just a known reference/starting point, separate from the 'injection timing' table. The table is not visible by default on EFI and there isn't a CAX posted on here, but it's out there, apparently. It's in the HPT tables, but obviously you can see that any change to boundary will directly affect the timing, just as B3702 would. I don't think you really need to alter boundary unless you're trying to change the timing significantly.

...Ok, that's the part I was not going to like...

ok, I guess we can play with table B3702 and not need to edit boundary.

joecar

January 21st, 2019, 06:07 PM

I simplified the equation, but if you 'write it out' I think it makes more sense. At least it did for me in trying to figure out what the math meant.

EOIT = -784 + 90 * boundary + 90 * B3702

360* would be end of exhaust stroke / start of intake stroke in the valve overlap area.

...

-784 was just observed to the starting reference point for the calculations (previously linked bluecat thread). So you just start there and work your way back from there based on those 2 values. I don't claim to be an expert or anything on this, just a guy who recently dug into it.

Sometimes what is needed is a different perspective, then things make sense again... thanks :cheers:

( I just started a new job, so I'm flat out learning all the new systems and code... the faster I go the further behind I get... lol )

joecar

January 21st, 2019, 06:23 PM

I'm rereading the HPT and EFILive threads on EOIT.

statesman

January 21st, 2019, 06:59 PM

I'm rereading the HPT and EFILive threads on EOIT.

Why does it even matter when your car is in pieces? :beer:

joecar

January 26th, 2019, 12:27 PM

I'm tuning (playing with) another car (at night, after work), cam has some overlap, I want to see how EOIT change affects anything... someone said VE changes, but I don't see how it can.

Yeah... my car is in pieces, I'm slowly making progress... will post some pics soon as get suspension all back together (bushings (1LE), lowering springs (500 lb/in vs 360 lb/in), swaybars, swaybar mounts)... also new fuel pump (while rear axle is droped), new exhaust, new shorty CARB compliant headers...)

hmmm, I'm looking at the FAST 102 LSXR (has CARB EO) but this needs messing around with new fuel rails and new 100 mm TB.

aaronc7

January 26th, 2019, 12:35 PM

What are the cam specs? It doesn't change VE in the actual sense of the meaning of VE, but best setting should yield lowest VE value/lowest injector pw. More 'efficient' / no wasted fuel I guess. If it's super aggressive cam and EOIT does indeed make a difference, then I would anticipate the low load/rpm VE table would need re-adjusted.

joecar

January 26th, 2019, 01:42 PM

I think cam is 228/232 112... mild... already been tuned.

joecar

January 26th, 2019, 01:53 PM

BTW: I recently started on a new job (Dec 3rd), I now work at www.karmaautomotive.com :santa1:

statesman

January 27th, 2019, 03:43 AM

I'm tuning (playing with) another car (at night, after work), cam has some overlap, I want to see how EOIT change affects anything... someone said VE changes, but I don't see how it can.

Yeah the VE can change, but it's like aaronc7 already said... the actual VE of the engine doesn't change but what does change is how well the fuel is atomized and mixed in the cylinder charge (which affects how well it burns) and that means you may need to adjust your VE table after changing EOIT.

Bigger cams see bigger differences when adjusting EOIT.

statesman

January 27th, 2019, 03:46 AM

BTW: I recently started on a new job (Dec 3rd), I now work at www.karmaautomotive.com :santa1:

Congratulations on getting your new job. :cheers:

I hope you're happy working there.

joecar

January 27th, 2019, 05:48 AM

ok , this cam has only 6 degrees overlap.

joecar

January 27th, 2019, 05:52 AM

Congratulations on getting your new job. :cheers:

I hope you're happy working there.
Hey thanks.

There's a lot to learn, but I am having a lot of fun here :cheers:

I mentioned to my boss taking a car to the local drag strip, he thinks it can be arranged... :)

Supercharged111

January 27th, 2019, 05:20 PM

I just thought I'd come in here and muddy the waters a bit. Some guy recently posted on Youtube about converting his LT1 over to a 411 PCM with minimal effort. He made the assertion that one could convert a 96-97 OBDII car to a 411 by simply pinning in a 411. The OBDII LT1 and Vortec 350 share crank reluctors and sensors, coils, similar ICMs, etc. I can't believe nobody has made this connection yet. He went to the extent of modifying his intake manifold to accept a distributor to run the 1X Vortec cam sensor. Later, he unplugged it and observed that the engine ran no differently. This got me curious, so a week and change ago I unplugged my cam sensor and have been driving the truck ever since with no apparent change in driveability. This guy wasn't full of crap. He stated that by disconnecting the cam sensor, you put the engine into batch fire mode for the injectors. Well for a race car running a stock motor, this really doesn't matter at all. I may be able to get a rule change implemented as the good Optisparks are not getting any cheaper and for a lot of people are a perceived downfall to the platform. Moreover, it really got me to thinking about this thread. Some people really believe it makes a difference, but others like me and this Youtube dude clearly have altered injection timing with no apparent effect. Mind you my 1500 is not a race car, I like to lug it around with a locked converter uphill at 1500 RPM so for it to still do what it does really begs the question how much does this really matter?

statesman

January 27th, 2019, 06:22 PM

This got me curious, so a week and change ago I unplugged my cam sensor and have been driving the truck ever since with no apparent change in driveability. This guy wasn't full of crap. He stated that by disconnecting the cam sensor, you put the engine into batch fire mode for the injectors.

Hmmm... now you've got me thinking.

Do you feel like doing a little experiment for me?

Supercharged111

January 28th, 2019, 02:51 AM

Depends on how easy it is/isn't. :D

statesman

January 28th, 2019, 05:50 AM

Oh it's not all that difficult. Since you're running without a cam sensor and possibly in batch fire mode (which I'm not entirely certain that it does put you in permanent batch fire mode), I'd like you to do a log of your trims while driving (to establish a baseline for your fuel trims) and then change {B3703}Injection Timing Trim to 2.55 across the board and then do another log of your trims while driving. I've never understood the purpose of that table... it doesn't appear to do anything in normal mode, so I was thinking that maybe that table is used when in batch fire mode... although even that wouldn't make a whole lot of sense, but anything is possible with GM.

Supercharged111

January 28th, 2019, 07:29 AM

I think I can handle that.

joecar

January 28th, 2019, 03:55 PM

Interesting... we'll see what B3703 does.

98SS2836

January 29th, 2019, 02:51 AM

Going to play with the calculators when some decent weather breaks. My cam has a good amount of overlap, so I guess I should see a change.

Supercharged111

January 30th, 2019, 04:19 AM

Got some data yesterday, but I goofed and logged LTFTs with and without cam sensor, didn't change the value at all. Will re-engage tomorrow and add STFTs as I ASSume you were after those as well. Fair warning, after yesterday's logs truck isn't looking so hot. Left side ran lean and stayed that way, right side didn't alternate enough so take it for what it's worth.

statesman

January 30th, 2019, 05:56 AM

Yeah, we will need STFTs as well. If it does change anything, the change might be small and only show up on STFTs.

If the left side is significantly lean, you should probably investigate that before worrying about this experiment.

Supercharged111

January 30th, 2019, 06:20 AM

Wideband lives in the left bank and showed 15-16:1, truck got weird after I corrected CMPRET and did a CASE relearn. It's been getting quirky lately, there's definitely a mechanical issue waiting to be discovered. I really didn't expect the effect to be so significant, the root cause is buried deeper than just a bad O2.

voda1

April 1st, 2019, 07:17 AM

By utilizing the 2 external inputs of my V1, or with the converted EGR and A/C inputs. Could monitor camshaft, crankshaft sensors as well #1 spark and #1 injector. Does the scanner support enough resolution to get something useful? What is the sampling rate? Kind of like picoscope output.

voda1

April 1st, 2019, 07:38 AM

When opening a stock 97C5 tune file in hptuners the boundry value is shown and quite different from later values.
7.22 boundry and 4.78 normal(B3702)

22741

joecar

April 6th, 2019, 09:43 AM

Scantool logs pids at 10Hz for LS1A/LS1B/P01 and 40 Hz for E38/E67.

joecar

April 6th, 2019, 09:44 AM

1997/8 LS1's do have various differences compared to later LS1's.