Injector Offset ?'s vs LS1 edit

[MN C5]

Man, all these new tables are giving me a head ache.. Pulled EFI FlashScan and LS1 Edit files to compare some of the things I'm used to working with and found the values differ substantially. Has anyone else run into this ?

Also does anyone have an understanding of what changing the value in the table actually does? Say at 10 volts at all represented MAP values you have .5000 and at 13 volts and all represented MAP values you have
.3000 for a table value. What change does the injector see ?

Thanks

Dennis

[John Skiba]

The injector offset table is a VERY important table to tuning in your car correct with aftermarket injectors like the 30lb SVO's, etc. Unfortunately, from most of the tunes I've seen it is also an ignored table most of the time. Even by professional tuners.

If you ignore this table and just do the math on the IFR table for larger injectors, the math will be off and your tune will also. Most people compensate by "massaging" the IFR table and MAF table to get the desired Ltrims. Unfortunately, doing it this way just made your life 10x harder. (See below picture for IFR table I download of a tune of someones. :shock: )

The offset table adjusts the injector pulsewidth on time based on voltage. Smaller values will increase ltrims and larger will decrease ltrims (larger commanding more fuel per pw).

Over 2 years ago this table drove me crazy. I was trying to figure out why the math for the IFR didn't work out. Using the stock offset table with SVO injectors for example will make your tuning that much more difficult. I got it pretty close (WB AFR was only off by .1 compared to commanded AFR and all the math worked out for IFR) however, I have been refining it more lately to get it dead on.

[MN C5]

Thanks John, I've got the base tune in mine now but know it can idle better than it does. I've got 735cc injectors from RC Engineering and sent them a email requesting offset values for these. I'll post their reply, Would anyone like to guess if a larger injector requires larger or smaller table values >>>

Dennis

[Dirk Diggler]

I hope someone can take the mystery out of that table

[John Skiba]

Thanks John, I've got the base tune in mine now but know it can idle better than it does. I've got 735cc injectors from RC Engineering and sent them a email requesting offset values for these. I'll post their reply, Would anyone like to guess if a larger injector requires larger or smaller table values >>>

Dennis

SVO injectors require larger offset values (say at 14V, .700 instead of stock .300 0kpa) than LS1 stock bosch injectors. RC will most likely have a single linear offset table like the Fords ECU's use. As you guys know, ours is a lot larger of a table. If someone has the ability to test the injectors vs voltage offset and make a table, that would be the best. :)

What are your injectors? Lucas, etc??? I can work up an IFR table for them and get you in the ballpark for the offset table if they are SVO type injectors.

To complicate things more, I'll also throw MAF table into the equation (you knew I was going to do this. ;) ). If you've messed with it, the IFR table & offset table, you will most likely be hopelessly chasing your tail (tune). Now guys are change VE tables to even further complicate things.

I was just discussing all this with Whitney actually and his car responded just like mine. Very predictable and repeatable with offset changes.

Folks... KISS .... If you have a C5 with an 85mm screenless MAF, use a Z06 MAF table and don't touch it. EFILive provides us with the power of the table editing. Doesn't mean it's benefical to change every table you see. :)

If anyone is using SVO or Accel (brand) injectors and would like to play with some offset tables and gather more data, feel free to email me your tune file and mod list.

John

[John Skiba]

Note: Above example for SVO offset is assuming an SVO injector test pressure of 43.51psi and not 39.15psi.

[Dirk Diggler]

What about racetronix 32's can you whip somthing up for that



Static Flow Rate @ 43.5PSI (300kPa) = 31.6 lb/hr = 332cc/min = 239g/m
Static Flow Rate @ 58.0PSI (400kPa) = 36.5 lb/hr = 384cc/min = 276g/m
Dynamic Flow Rate @ 43.5PSI (300kPa) = 6.68 gm/pulse - 2.5ms pulse width and 10ms repetition rate
Dynamic Flow Rate @ 58.0PSI (400kPa) = 7.72 gm/pulse - 2.5ms pulse width and 10ms repetition rate
Coil Resistance: 16.2 Ohms / High Impedance / High-Z (No ECM driver modifications required)

[John Skiba]

What about racetronix 32's can you whip somthing up for that

Show me pictures of the injectors, supply some numbers off the injectors or all of the above. The more info the better. Don't know who's injectors racetronix uses as I haven't looked into it. Are they bosch injectors??? Should have a 0 xxx xxx xxx number or something like that. Sorry, I'm doing all this from memory, when I get home late tonight, I'll look over some of this stuff as it's been a while.

[Dirk Diggler]

http://www.racetronix.com/621020.html

I provided more information afte you quoted me

[John Skiba]

I used to have Lucas injectors years ago. If I recall, they were closer to stock function but I can't confirm that. Again memory.

I know someone has to have the offset tables out there. Years and years ago when I was looking into this, I think it was Chris Bennight that got the original Ford numbers??????

[AllCammedUp]

I was just discussing all this with Whitney actually and his car responded just like mine. Very predictable and repeatable with offset changes.

Folks... KISS .... If you have a C5 with an 85mm screenless MAF, use a Z06 MAF table and don't touch it. EFILive provides us with the power of the table editing. Doesn't mean it's benefical to change every table you see. :)


All I can say is that John is definitely on to something here. I've been testing some offset tables for him, and the trims are getting better and better... I've never been able to get them as close as they are now with 'old school' tuning approaches (endlessly changing the MAF and IFR table).

The car feels very strong through the rev range, and it's immediately noticeable if I switch back to the stock offset table with the SVO IFR table - it's amazing how I couldn't tell the difference before (running the SVO 30#'ers and the stock offset table) and switching to John's calculated offset table with the SVO 30#'er IFR table - it's a huge difference in driveability.

It's helping to get the AFR's more in line in regards to commanded vs. actual, and then I think the hope is that there will be less and less tweaking of the VE necessary for part-throttle tuning and PE transitions. You'll still be tuning PE the same way, naturally.

[bink]

My car ran much truer to Commanded AFR once I was able to get an offset table for my injectors .
I'm running the GTP supercharger/ World Challange injectors.

John Skiba - as you know, I had searched for definitive info on these injectors for quite awhile.
36# at 43# fp and 42# at 58# fp. The ASA (2000 LS1PCM) bin IFR table works out for the 36#s scaled for 58 #.

Anyway, I used the ASA offset table and it cleaned up my AFR considerably.

Recently I realised that the MAF table in the the ASA bin is scaled to 497 g/sec. I then checked the lower values of the ASA MAF table ( around 3250 Hz) and they closely match my MAF table which I rescaled - after almost ten months of trying many different "fixes" for my lean idle!! I then remembered that I had used the Offset table from the ASA tune and compared the ASA IFR table and my randomly scaled IFR table - they are within 0.4 g/sec of each other. I suspect they will be closer when I try the ASA MAF table.
FWIW.

I think the Offset table is critical but I wonder if it needs to be experimentally derived?
The Bosch- GM 36#ers are supposed to be the same as our stockers internally - yet the ASA Offset table (assuming the ASA cars run these injectors) differs significantly from my stock Offset table.

Cheers,
joel

[MN C5]

I ended up calling RC but here is what they gave me for offsets for 72lbers or 750cc @ 4bar or 58psi

16v 1.20ms
15.5 1.23ms
15.0 1.26
14.5 1.30
14.0 1.36
13.5 1.42
13.0 1.46
12.5 1.53
12.0 1.63
11.5 1.7
11.0 1.81

[Dirk Diggler]

Racetronix couldnt give me the information. THey said it was VCM/car specific

Bink

Can you email me the ASA tune so i can see the offsets and the IFR table as my injectors are rated at 36 lbs/hour@58 psi

[wait4me]

I have a bunch of 98 asa files.. they not locked and editable. But you guys cant see them in the editor yet.. Ill post them all when the 98 stuff is released.

[John Skiba]

Bink - Stock 23/24lb bosch injectors and 36lb GTP bosch injectors may look the same but I'm sure the pintle size, springs, etc are different. All which probably contribute to different event timing and thus flow characteristics. This is best answered by an injector engineer.

What kind of intake setup do the ASA cars have? Is it a similar setup to the Fbody cars? Asking because you said your results were close.

Most setups don't vary to far from the factory setup. Example: A C5 intake is still very similar with an aftermarket airbridge and MAF location etc to stock setup. That's why I use the stock ZO6 screenless table with a 85mm screenless maf on a C5 and not a truck 85mm MAF table on a C5.

If we know the flow rate for an injector at a given pressure, then the math should work out. However, we all know that is not the case and most people adjust the MAF table and or tweak the IFR table to compensate. I'm sure Ross can explain all the math calculations, etc involved with a proper MAF reading a lot better than I can. I just prefer to have a sensor read correct (maf, etc.) Just seems like it would make life a lot easier.

Something we didn't discuss yet is the effect of fuel pressure on an injector. Injector timing events are probably going to be quite different at 43.51psi compared to 58.01psi, etc.. etc.. I remember seeing charts of the effects of FP on rochester, bosch, lucas, etc injectors and the rochester would not increase in fuel delivery with any linearity as fuel pressure increased right upto 90psi where it failed. From 65psi to 90psi fuel delivery did'nt increase. (Anyone running a rochestor with FI?? ;) :D )

BTW, If I recall right, torque is a calculated function. Anyone want to take a guess from what? Again, Ross or someone else can explain the finer details better than I can.

John

PS. If anyone knows anyone from Kinsler Fuel Injection in Troy MI, they can probably shed some light on this topic. ;)

[John Skiba]

Ross/Paul - Thank you for the "Small pulse Adjust" Heh... no wonder...

[QUICKSILVER2002]

I agree that the offset table is the ignored table that needs more attention. People don't want to mess with it, but not getting it right causes all kinds of other problems. There are some injectors that work just like stock, but there are many others that do not.

Here is an old post from ls1tech by a "professional tuner" - who was trying to scare people away from the injector offset table.

People farting with this table are walking on a live bomb.
Guess what happens when someone sets the delay incorrect and the injector is coming on too early or late of sparkplug firing ?

Being that table starts in milliseconds and by PE is microseconds, there is zero reason to play with those values esp since the internal coil ramup time esp on multech II were designed to react faster then older designs did.
The SVO #30 is NOT made by Ford, they are by Bosch, the same vendor who makes the injector for the LSx engines and have the same coil specs.

DOwn the road people cocking with this table may see piston or head damage from out of timing injectors firing at the wrong time.

I've seen countless LSXs using the SVO;s with great performance and all maintained the stock injector offset tables.


Just goes to show you why people have been scared away from it.

Anyway, I was just playing with offsets tonight and would like to clarify my understanding.

The voltage is the same voltage you see on your volt gauge, right? So the values below 10 and above 14 are probably never seen?

It seems that the PCM has a known stopping point for an injector pulse (I'm assuming this is based on crank position). Longer pulse widths mean an earlier start, but it always ends with the same basic timing.

So increasing the injector offset (time to open) actually adds to the overall pulse width.

I really feel this is the key to the tuning problem I have been having with my car. I have 60lb mototron injectors and a vacuum refrenced regulatur (my IFR table is flat)

I get the car running great (during the day) and then I drive it at night and the idle starts to stumble a bit. It also does this during the day when the fans have to kick on full speed.

I feel this is related to the fact that the injectors behavior is being impacted by the cars voltage. The entire idea behind the injector offset table is to make voltage changes have no impact on amount of physical fuel being delivered.

If all this is true, what would be an easy way to dial in voltage. I was trying to think of a way to regulate the voltage and test with the extremes. I can probably just do trial and error with a lot of data, but it sure would be cool to run the car at 10,11,12... v and tweak until the o2s read exactly the same.

Another thing that makes the tuning a pain is the fact that the alternator starts putting out much less power when it gets hot.

[bink]

John - I think the ASA cars are pretty much a straight shot air intake (no bend). Mine is a Vette. wait4me should be able to confirm this.




People farting with this table are walking on a live bomb.
Guess what happens when someone sets the delay incorrect and the injector is coming on too early or late of sparkplug firing ?

Being that table starts in milliseconds and by PE is microseconds, there is zero reason to play with those values esp since the internal coil ramup time esp on multech II were designed to react faster then older designs did.
The SVO #30 is NOT made by Ford, they are by Bosch, the same vendor who makes the injector for the LSx engines and have the same coil specs.

DOwn the road people cocking with this table may see piston or head damage from out of timing injectors firing at the wrong time.

I've seen countless LSXs using the SVO;s with great performance and all maintained the stock injector offset tables.


I believe this is the same Guy that said he uses the GTP/36 lb/hr injectors ( (42# @ 58 psi) and stated on LS1Tech that there was no need to use a diiferent offset table (i.e. use the stock offset table). Well the offset table in the ASA tune is for the GTP/36# injectors (confirmed by wait4me) and it's quite a bit different than the stock table. I guess GM should have consulted with him.

Isn't he also the Guy that claimed 5 gallons of gas would reset the Octane Scalar to 100% High Octane table?


Excellent point Quicksilver 2002 - IMHO.

There was a thread awhile back on pulsewidth.
If you do the Math the injectors are shooting at the backside of the closed intake valve - most, if not all, of the time. This is confirmed in Will Handzel's book " Modifying and Tuning Gen 3 Engines ".

FWIW.

Cheers,
joel

[wait4me]

Hi guys, The Injector offsets are set per injector type and injector size, That is The only thing that effects that table.
They are a strait foward number they should be, and to get the math calculation all you have to do is look at all the ones the gm has set up for you between all the years. But that would only work for a injector type that has been used by gm, Not a ford type or any of the fat shorter injectors..
Intake air or the inlet going into the motor would not effect the offsets. They Do effect fueling and they should be as correct as possible, But if they are already set, you shouldnt mess with them for fine tuning..
Gm's tables are acurate as you can get.. So if you put in the correct tables from a gm stock tune, then that is not something to mess with.
Getting information on how to set up ford or the other injectors is gunna be a pain for anyone. I tried years ago and i was lucky enough to get an accurate maf flow chart...

[John Skiba]

Guys, I am not here to say THIS is the correct or incorrect way to do it. There are MANY tuning methods out there on the NET. I agree with some and disagree with many. I am merely sharing my own personal experiences from over 2+ years ago.

That being said, I just recently revisited the offset table because NOW we have all sort of support tables and VERY cool tools to collect this data with. Thanks EFILive! ;)

2+ years ago, using LS1Edit, a Techedge wideband, I wanted to tune the car for maximum performance while keeping things simple and together. This meant using a known (GM MAF Table - Z06 85mm screenless) since that's what I was using, using 32lb injectors with math correct IFR table (since this is a known by flow data).

I merely wanted the PE table to be predictable. Meaning, if I commanded 12.9 AF in the PE table, then my wideband will also show 12.9 AF. After all, isn't the commanded AFR supposed to match the actually AFR? :P Is trying to keep things simple to much to ask for?

At the time, I was looking at "Professional" tunes for help. What I found instead simply left me in :shock: . 2+ years later, some things haven't changed... good or bad.

Anyway, the offset table was derived from a known offset table for the injectors. It worked. It still works. All tuning was and still is predictable and easy. Never blew up the motor despite having 86+ thousand miles on it and still running strong 95mph/119mph w/ A4 through a baby cam 216/220. Remember, this was WAY before the VE and SD rage! Now, I'm going to VE tune and by the looks of it, my VE tune isn't going to be crazy changes with MASSIVE spikes and valleys, etc. Just a nice little fine tune. Hopefully.

So, I figured I'd have others try it and so far good results. The below screen shots are from a beta testers LTRIM's with a first crack at 30lb injectors with stock offset table and 30lb injectors with matching modified offset table. NO VE tuning done, etc. This is a cammed car, 224 I believe.

Looks like it worked all while retaining the proper IFR table and I'm sure AFR. But hey, it ALL only my opinion! :)

There are MANY people from all walks of life that read this board, feel free to drop me a note with any thoughts about this.

Happy tuning all!

[bink]

John - Thanks for he post and images :D .

I'm in total agreement as to the importance of correct offset tables. I don't have proof but I know how much my Wideband O2 (FJO) AFR vs Commanded AFR cleaned up after I used the correct offset table with the GTP injectors. I'm open loop (NoGo VE tune) - so I don't have the fuel trims.

Cheers,
joel

[oztracktuning]

I have found Chris Bs spreadsheet for SVO 30s on the the LS1 Edit Faq website

Its based on the Ford offsets

At the Voltages 6, 8, 10, 11, 12, 13 ,14, 15 ,16 and at O pressure

4.6475
2.1182
1.3965
1.1973
1.0313
0.9033
0.7861
0.7148
0.7148

How much can we trust these values?? Are they close to what you are seeing John ?

I have a spreadsheet of numbers i can try.
Eg at 13.0V it is

0.899079
0.99541
1.091739
1.12385
1.155959
1.18807
1.18807
1.18807
1.220179
1.220179
1.220179
1.25229
1.284398
1.284398
1.316509
1.316509
1.316509

[oztracktuning]

I notice that if moving between 12.5V to 13.5 at 50MAP the change is only from 1.218ms to 1.261ms in the spreadsheets values

rather than from 0.653 to 0.547ms as in 'my' stock ones.

Both values move in different directions??

I dont trust the way the data works out.


The original spreadsheet is at http://ls1edit.slowcar.net/injectoroffset.xls

[oztracktuning]

I just prepared these values between 11.5V and 14.5V to use.

0.926358 0.861813 0.802884 0.749232 0.700744 0.657730 0.621406
0.947780 0.881742 0.821451 0.766558 0.716949 0.672940 0.635776
0.969202 0.901672 0.840017 0.783884 0.733153 0.688150 0.650146
0.990624 0.921601 0.858584 0.801210 0.749358 0.703360 0.664516
1.012046 0.941531 0.877151 0.818536 0.765563 0.718570 0.678886
1.033468 0.961460 0.895717 0.835862 0.781767 0.733780 0.693256
1.054890 0.981390 0.914284 0.853188 0.797972 0.748990 0.707626
1.076312 1.001319 0.932851 0.870514 0.814177 0.764200 0.721996
1.097734 1.021249 0.951418 0.887840 0.830382 0.779410 0.736366
1.119156 1.041178 0.969984 0.905166 0.846586 0.794620 0.750736
1.140578 1.061107 0.988551 0.922492 0.862791 0.809830 0.765106
1.162000 1.081037 1.007118 0.939818 0.878996 0.825040 0.779476
1.183422 1.100966 1.025684 0.957144 0.895200 0.840250 0.793846
1.204844 1.120896 1.044251 0.974470 0.911405 0.855460 0.808216
1.226266 1.140825 1.062818 0.991796 0.927610 0.870670 0.822586
1.247688 1.160755 1.081384 1.009122 0.943814 0.885880 0.836956
1.269110 1.180684 1.099951 1.026448 0.960019 0.901090 0.851326

Can anyone indicate what the risk is in trying these values - the stock ones are below in the same range

0.714283 0.607900 0.516715 0.425530 0.364740 0.303950 0.273555
0.744678 0.638295 0.547110 0.471123 0.410333 0.364740 0.303950
0.775073 0.653493 0.577505 0.516715 0.455925 0.395135 0.349543
0.775073 0.668690 0.592703 0.531913 0.471123 0.425530 0.364740
0.805468 0.683888 0.607900 0.547110 0.501518 0.455925 0.395135
0.805468 0.683888 0.607900 0.562308 0.516715 0.455925 0.395135
0.820665 0.699085 0.623098 0.562308 0.516715 0.471123 0.395135
0.835863 0.714283 0.623098 0.562308 0.531913 0.471123 0.395135
0.851060 0.714283 0.638295 0.577505 0.531913 0.471123 0.395135
0.866258 0.729480 0.638295 0.577505 0.531913 0.486320 0.410333
0.866258 0.729480 0.653493 0.577505 0.547110 0.486320 0.410333
0.881456 0.744678 0.668690 0.592703 0.547110 0.501518 0.425530
0.896653 0.759875 0.683888 0.607900 0.562308 0.501518 0.425530
0.896653 0.775073 0.699085 0.607900 0.577505 0.501518 0.440728
0.911851 0.805468 0.699085 0.623098 0.577505 0.516715 0.455925
0.927048 0.820665 0.714283 0.623098 0.577505 0.516715 0.471123
0.942246 0.835863 0.714283 0.623098 0.577505 0.516715 0.471123

[joecar]

I can't say anything about risk either way...

I don't think it could hurt, since isn't the injector closing event the fixed timing point and these values just move up the opening event...?

The gradients are in the same directions so it would probably be okay.

I'm interested in how you obtained the new values...?

How do you measure the effect of the new values...?

Regards
Joe
:cheers:

[oztracktuning]

I got the Ford ones - that just rate zero. I took a punt on the 0 to 80 pressure spacing (top to bottom) - looking at the stock values and at the other suggested values in the ls1edit faq spreadsheet - then i just let them do a linear fill in between - vertically only between the zero pressure cell and the 80 cell for that voltage.

I am hoping to see what John Skiba has to say about them. These SVO 30s seem to give people issues at idle - mine are fine everywhere else - i am guessing and hoping that this table may be why.

[jfpilla]

I've had an SVO 30 Offset Table for some time. I used the calculator with some values that, I think, Allcammedup had posted on the Corvette Forum. I forgot I had it because I was concerned about doing something bad. This thread gave me the push to try it out. Man, I wish I had done it long ago. I'm now using the stock MAF table. Trims are more equal from cell to cell, rafacig is -3 to +2, iacltdac is -2 to +2, the best they have ever been. No BS when I say that the car is idling and running as smoothly as when I had it in SD.
I'm not suggesting anyone do it. I still have some residual fear and want to run it a few days and see how it holds up.

[joecar]

... isn't the injector closing event the fixed timing point and these values [the offset table] just move up the opening event...? Would this be a correct statement...?

[jfpilla]

Would this be a correct statement...?

I think so ,although, I still don't really know what I'm doing. My thinking is to attempt to inject the same total amount of fuel as when my MAF values were higher, but do it over a longer period of time. The larger injectors apparently are slow at low RPM, so it seems to make sense that injecting fuel sooner could smooth things out. I suspect that we all know this but don't have an SVO 30 table that we are confident is right.
I should mention that Dynair matches perfectly with MAF up to 3000rpms. That's the highest I've reved so far. Cells 7, 10 and 11 seem to lock at 0 consistantly. I need to go to the track to test, as John said, the predictability of the PE table.

[jfpilla]

473SVO 30 table?

[oztracktuning]

Did you use the values in the bottom table that are displayed when you first open the sheet. (not edited)

They are radically different from mine. The difference 0 to 80 is much less and many numbers are the same?? Maybe thats a good thing - maybe its not????

[jfpilla]

Did you use the values in the bottom table that are displayed when you first open the sheet. (not edited)

They are radically different from mine. The difference 0 to 80 is much less and many numbers are the same?? Maybe thats a good thing - maybe its not????

I don't have an understanding of how the values affect fueling. I plan on lots of logging to see what happens with any changes made.

[jfpilla]

joecar,
I'm being told that the correction is to the IPW and not to only when the injector opens???

Flyer,
The table appears to be okay for getting close. I've made adjustments that you can see in the attachment. You can log GMManifoldVacuum and Battery Volts. Also can set up a Map to match the Correction table row and column and will give you correction factors

[joecar]

Hmmm, interesting.... so this is being added to extend the IPW.

[oztracktuning]

I just tried the set of data that i posted previously - just changing between 11.5 and 14.5V.

The initial impression is that it is maintaining more steady afrs and idling better. It did richen up the mixture everywhere though.

I will now do my VE table to suit the changes and see how things work. It only takes one flash to go back to the normal offsets.

Interesting that i have been trying to go back to closed loop at idle rpm i just turned it back off by making most of my 400-800-1200rpm cells to ask for 14.77 instead of 14.63. It is much smoother in open loop as well.

The lower map cells are the richest. With the difference being about about 2-3% richer at 100map to 8% at 40 map to 11% at 30map.

[hpcubed]

joecar,
I'm being told that the correction is to the IPW and not to only when the injector opens???

Flyer,
The table appears to be okay for getting close. I've made adjustments that you can see in the attachment. You can log GMManifoldVacuum and Battery Volts. Also can set up a Map to match the Correction table row and column and will give you correction factors

I am not an expert but it would seem that the injector offset is compensating for the turn on time of the injector. The turn on time is added to the beginning of the commanded pulsewidth. If your injector takes longer to turn on, it must be opened sooner so the fuel is delivered at the correct time. Does this make sense?

Also does anyone have a table for 60 lb mototron's???

[jfpilla]

I am not an expert but it would seem that the injector offset is compensating for the turn on time of the injector. The turn on time is added to the beginning of the commanded pulsewidth. If your injector takes longer to turn on, it must be opened sooner so the fuel is delivered at the correct time. Does this make sense?

Also does anyone have a table for 60 lb mototron's???

As I said I really know little about this subject and would like to see some experts chime in. I have talked to a number of more knowledgeable people than I. What I get is that the table is there to compensate for Manifold Vacuum and Battery Voltage changes and affects pulsewidth and not just the opening time. The timing table is there for that reason. We have put in new flow rate numbers for our injectors, but the SVO's have a different operating curve. Whether we are affecting timing or not is not all that critical, what is important is to find the right curve.
I've been logging normal daily driving. The cells that get hits are between 11.5 and 14 volts and 35 and 60 Vac. Of those the significant hits are in 13-14 volts and 45-50 Vac. So it's not that hard to find the values that give acceptable trims for cruising. What concerns me is what happens throughout the vacuum range when I go WOT.

[oztracktuning]

I have been trimming my VE table for a few logs now since using the SVO 30 values i posted earlier. It hasnt made as much difference to the 100 MAP area about 3% . But by 50 MAP its about 8%. Then at 25MAP its 25%. In each case that is the % the VE table has been reduced.

Not sure how this stacks up against the change in % of injector pulse width.

Maybe it can be calculated whether the change has helped in terms of the required offset for the injectors. ??

[oztracktuning]

JUst playing with some of the calculations. It seem that at say 1600rpm and 25map if that is indeed -75 manifold and at 13.0 V - the extra length of the pulse should have richened my car by around 28%. So far i have trimmed to 24.5%. But there may be more needed and im not sure how precise the VE cell was pre-offset change ( i can check old logs though).

If the offset is not long enough with the stock settings for the SVO30s - you would expect that some of the pulse width that is needed for fuel will be taken up by the extra time needed to fire the injector. So maybe having enough offset - will cause this to be gained back by needing less trimming - if the settings need less than 28% trimming - the difference may be the true difference in offset??? Maybe ive got it all wrong.
Maybe all that matters is in what happens when the voltage changes. Then maybe things will be more precise ??

[bink]

all that matters is in what happens when the voltage changesThat's my understanding of it. Further refinement of final AFR .
FWIW.
Cheers,
joel

[jfpilla]

The attachment shows the ltft's for my normal driving. It seems that the offset curve depends on GM MANVAC and BATTERY VOLTS.

[TAQuickness]

Been lurking for a while and have a few questions...

What does this table actually do/represent? It appears this table will adjust the IPW based on MAP and battery voltage. Are we sure that's what it's doing?

What physical properties of the injector/fueling system warrant molestation of this table? I would think coil resistance and valve design (pintle, disc, etc..) would warrant changes, but are those the only factors? Which factors have the most significant impact to this table?

Given an OLSD tune, can an error factor for Injector Off Set table be calculated?
Based on John's posts, if you have a known good MAF calibration, and your IFR table is correct, you now have 2 constants to tune the offset table with. However, in OLSD, with the IFR as your only constant, if you tune your VE table to a commanded 14.63 AFR, then change commanded AFR to say 13.0, it appears you VE table needs more tweaking, when the culprit may be the off-set table. Can the subsequent VE table error somehow be used to calculate a correction factor for the IOS table?

If an error factor cannot be calculated for the IOS table, how do you actually create a valid IOS table?

[MN C5]

The fuel injector is basically a selinoid




Reluctance (NOT RESISTANCE) is a form of electrical resistance unique to coils. Electric current flows through the coil’s windings, it builds a magnetic field pulling the pintle off its seat and releasing the fuel. The time it takes for this to happen is directly influenced by the voltage applied to the circuit. And as that field grows, its lines of magnetic force pass through the same windings, causing a reversed-polarity voltage resisting the applied current. As the reluctance disappears about the time the coil reaches full saturation, the lines of magnetic force become stationary and theapplied current reaches its maximum. When the PCM cuts the injector coil circuit, the magnetic field collapses. But as it collapses those same magnetic lines of force pass through the coil windings in the other direction, thus extending the duration of the magnetic field and the opening of the nozzle.

The injector offset is I think there to allow you to tune for different sized coils and adjust for there reluctance. Different sized coils will act differently depending on the number of windings/turns and other factors. I've used the injector offset as a tool to help bigger injectors idle.:muahaha:

Dennis

[jfpilla]

Been lurking for a while and have a few questions...

What does this table actually do/represent? It appears this table will adjust the IPW based on MAP and battery voltage. Are we sure that's what it's doing?

What physical properties of the injector/fueling system warrant molestation of this table? I would think coil resistance and valve design (pintle, disc, etc..) would warrant changes, but are those the only factors? Which factors have the most significant impact to this table?

Given an OLSD tune, can an error factor for Injector Off Set table be calculated?
Based on John's posts, if you have a known good MAF calibration, and your IFR table is correct, you now have 2 constants to tune the offset table with. However, in OLSD, with the IFR as your only constant, if you tune your VE table to a commanded 14.63 AFR, then change commanded AFR to say 13.0, it appears you VE table needs more tweaking, when the culprit may be the off-set table. Can the subsequent VE table error somehow be used to calculate a correction factor for the IOS table?

If an error factor cannot be calculated for the IOS table, how do you actually create a valid IOS table?



Originally Posted by TAQuickness
Been lurking for a while and have a few questions...

What does this table actually do/represent? It appears this table will adjust the IPW based on MAP and battery voltage. Are we sure that's what it's doing?

......Have to log GMMANVAC to link for tuning. The table is from 0 to 80.
......It must adjust IPW. When I lowered my MAF to stock I had to increase IO. It can also be seen in the logging afer making changes.

What physical properties of the injector/fueling system warrant molestation of this table? I would think coil resistance and valve design (pintle, disc, etc..) would warrant changes, but are those the only factors? Which factors have the most significant impact to this table?

......I don't feel like a molester. Whatever the mechanical differences of SVO's I don't know. We think they have a different curve. That's what I'm trying to see.



Based on John's posts, if you have a known good MAF calibration, and your IFR table is correct, you now have 2 constants to tune the offset table with. However, in OLSD, with the IFR as your only constant, if you tune your VE table to a commanded 14.63 AFR, then change commanded AFR to say 13.0, it appears you VE table needs more tweaking, when the culprit may be the off-set table. Can the subsequent VE table error somehow be used to calculate a correction factor for the IOS table?

........I'm trying it from the other end. Hopefully I can get reasonable trims across the board with the MAF and then run in SD and see the affect on PE and VE's, if any. There should be on PE if IPW is affected by IO. PE would seem to be the hard part because it requires so many WOT runs to get good info and the make changes. I was told by a tuner not to bother. Just get close and adjust PE accordingly. He said he has done thousands of tunes and has never seen perfect PE math. Might get lucky.

Given an OLSD tune, can an error factor for Injector Off Set table be calculated?
........Good luck.

[bink]

The attachment shows the ltft's for my normal driving. It seems that the offset curve depends on GM MANVAC and BATTERY VOLTS.
Cool. :mrgreen:

My idle (open loop, through the MAF) was more stable in terms of AFR and quality once I inserted the GM Offset table for the GTP/WCC/36lb injectors.

Have a Great weekend Joe!!

Cheers,
joel

[Dirk Diggler]

is that 36 ls/hour@58 psi or 43.5

[jfpilla]

Cool. :mrgreen:

My idle (open loop, through the MAF) was more stable in terms of AFR and quality once I inserted the GM Offset table for the GTP/WCC/36lb injectors.

Have a Great weekend Joe!!

Cheers,
joel

Joel,
Rub it in. Where can we get a table for SVO's?
Enjoy yours too.
Joe

Dirk,
I'm using 43.5. It seems to work as far as tables lining up. I know that there is 40.0 as a possibility. Given the end game it doesn't matter too much.
I may need bigger injectors late spring anyway. I may have to go with injectors that have tables available. LIKE JOEL's.
Joe

[MN C5]

My comments are just my opinions, feel free to correct me if you think I'm wrong.

You shouldn't adjust the IPW with offsets.. You can affect IPW by not understanding the values you put in the offset table. Adjusting these values will increase or decrease the amount of time the PCM thinks it takes to reach fully open and fully closed for the injector.

Injector offset affects both the opening and closing of the injector.

I think someone posted that you can adjust IPW's by tweaking the offsets. You should read my previous post in this thread. My guess is that the injector manufacturers base their offset values from the performance characteristics of the coil portion of the injector.

[jnorris]

Some more food for thought.
The 98 Corvette and the 98 Z28 uses the same 28.8lb injector but the injector offset tables are different for all entries. TheVette values are higher except from 4.5v – 6v where they are lower. At 13v/50kPa they are 0.167173ms longer.
Maybe this is due to a longer wiring harness and more resistance or maybe just IPW trim.


John

[bink]

is that 36 ls/hour@58 psi or 43.5

Neither, that's at the GTP pressure (48 psi?).
From the Bosch Motorsport Catalog, that Marcin found they are:

34.54 lb/hr @ 43.5 Psi ( 3 Bar)
39.89 lb/hr @ 58.02 Psi (4 Bar)

Cheers,
joel

[WicketMike]

Neither, that's at the GTP pressure (48 psi?).
From the Bosch Motorsport Catalog, that Marcin found they are:

34.54 lb/hr @ 43.5 Psi ( 3 Bar)
39.89 lb/hr @ 58.02 Psi (4 Bar)

Cheers,
joel




so what numbers would you put into the spreadsheet 39.89 @ 58.02?

and what about 42lb injectors?

thanks!!!!

[Tordne]

I have been watching this thread for a while hoping for the silver bullet that suddenly made all the injector tables make sense, especially the Voltage Offset table. Sadly it appears that it is still a bit of a black art.

It would be nice to be able to produce a map that essentially used a factor (similar to BEN) to map out the correct Offset table.

Anyone?

Cheers,

[MN C5]

Without the performance characteristics of the injector coil you wouldn't be able to calculate the injector offsets. It's really not a black art, the unknown value is the reluctence of the injector coil at various voltages. Could be that some manufactures cheat the larger injectors by changing the offset value.

:banana:

[bink]

so what numbers would you put into the spreadsheet 39.89 @ 58.02?

and what about 42lb injectors?

thanks!!!!


39.89 lb/hr = 5.026 g/sec.
This is the flow rate at 0 kPa Vacuum (101.3 kPa atmospheric).

Here are the values I use:


Injector Flow Rate (Grams/Second)
Manifold Vacuum kPa Value
0 kPa - 5.031250 g/sec
5 - 5.093750
10 - 5.101563
15 -5.148438
20 - 5.179688
25 - 5.203125
30 - 5.218750
35 - 5.250000
40 - 5.304688
45 - 5.335938
50 - 5.359375
55 - 5.375000
60 - 5.406250
65 - 5.421875
70 - 5.468750
75 - 5.484375
80 - 5.539063

Cheers,
joel

[bink]

Without the performance characteristics of the injector coil you wouldn't be able to calculate the injector offsets. It's really not a black art, the unknown value is the reluctence of the injector coil at various voltages. Could be that some manufactures cheat the larger injectors by changing the offset value.

:banana:

And you also have tables B3702, B3703, B4001, B4003, B4004 and B4005 - which all seem to be injector specific.
I wonder if RC Engineering. or similar injector service co., can determine these values when they flow and blueprint??

:cheers:
joel

[joecar]

If there was a means of measuring and correlating the mechanical motion and the electrical waveform
for opening and closing of injectors, that would clear all this up...

[MN C5]

And you also have tables B3702, B3703, B4001, B4003, B4004 and B4005 - which all seem to be injector specific.
I wonder if RC Engineering. or similar injector service co., can determine these values when they flow and blueprint??

:cheers:
joel

Good question Joel, I wonder if they could. You'd think they certainly should have the answers.
:exactly:
Perhaps because the values being dealt with are so small (millisecounds) that changing some of the other values has little affect on how the injector performs.

[TAQuickness]

Unless I missed something, I don't think you need a MAF to do this. Just to make sure my foot doesn't fit in my mouth, I'm gonna go try a few things before I elaborate too much.

[turboberserker]

A way around this may be to look at a peak and hold injector driver. I went with an acceleronics versafueler, which allows me to run stock offset tables (Perhaps with minor tweaking down the road) and get very high quality, low pulsewidth performance from the new 72# delphi (low z) injectors. As of my last drive this morning, I am sometimes seeing a steady 1.7-1.8 pulsewidth at decel and idle. From a fuel point of view, it is almost like my wife's stock Avalanche (you have look past the cam bumpin ;))

I ran the truck briefly (~15min) at idle with the old 60# motos and it was smoother than without the versafueler for sure... My idle AFR was 15.0 without the device, and 13.8 after installation (and no change to the tune file) -- thats pretty good pulsewidth that could be reclaimed.

The driver works with either high or low z injectors.

[oztracktuning]

I have with my offset values met a bit of a problem.
I have been trimming and trimming my VE table and having trouble getting some cells to become lean enough. I have even tried reducing the low map offset values eg the ones at 80-55 manifold pressure ie 14-45map.
It helped a bit but some cells dont want to lean out.

The culprits are
1200rpm at 25map 0.922
1600rpm at 20map 0.87
1600rpm at 25map 0.90
1600rpm at 30map 0.92
2000rpm at 20map 0.89
2400rpm at 20map 0.94
3200rpm at 20map 0.88


All other cells are fine. Including
2800 at 15 map and
surprizingly 3200 at 15 (when 20 was bad??)

I am wondering if i need to tweak the minimum pulse width settings or something?? What can i do.

The car is set at the moment with DFCO turned off. Should i turn the DFCO and not worry about it or maybe even just go back to the stock offset figures. I had the AFRs good everywhere before???

Good if someone can help - i am technically stuck.

[hpcubed]

Ok, I installed my 60 lb mototron inj. IFR table from spreadsheet etc. When I hold the rpms constant at 2K, the car misses and I can see the AFR go from 14 to about 15 or 16 momentarily. I am thinking that the 60 lb inj require more time to open. So I start increasing the offset table in 10 % increments. At 30 to 35% increase, the miss is gone. However, I am running very rich at higher rpm (no load so far). So, for for my application, it seems the offset table needs to be tweeked. I will now reduce the lower manifold vacuum values to probably 15% then do some logging to dial it in further.

I have heard that some people only adjusted the IFR table for these injectors and they run fine. It is a little frustrating if this is true and why would it be diff. for my application? I question if I am compensating for a bad injector.

[oztracktuning]

I have found out the problem is that SVO 30 injectors use older technology and cant open any shorter than what mine are now. So the problem is unsolvable with these injectors. I have gone back to the original offsets at the moment....

[Delco]

Ok, I installed my 60 lb mototron inj. IFR table from spreadsheet etc. When I hold the rpms constant at 2K, the car misses and I can see the AFR go from 14 to about 15 or 16 momentarily. I am thinking that the 60 lb inj require more time to open. So I start increasing the offset table in 10 % increments. At 30 to 35% increase, the miss is gone. However, I am running very rich at higher rpm (no load so far). So, for for my application, it seems the offset table needs to be tweeked. I will now reduce the lower manifold vacuum values to probably 15% then do some logging to dial it in further.

I have heard that some people only adjusted the IFR table for these injectors and they run fine. It is a little frustrating if this is true and why would it be diff. for my application? I question if I am compensating for a bad injector.

You need to adjust the IFR table and the VE table to get the mixtures right , adjusting the injector pulsewidth voltage table is not the right place to be looking, its a offset for varying voltage and needs some special equipment to get it right

[TAQuickness]

You need to adjust the IFR table and the VE table to get the mixtures right , adjusting the injector pulsewidth voltage table is not the right place to be looking, its a offset for varying voltage and needs some special equipment to get it right

what kind of equipment?

[Delco]

what kind of equipment?

A full injector test bench with variable voltage , pcm simulator etc

[BigTex]

I have a few comments on this topic and may be completely wrong, but may not...

The way I understand the injector offset, its an adder to the total pulsewidth used to make up for the time it takes the injector to fully open and close. So once the PCM calculates the needed fuel and determines the injector time, it looks up the offset and adds that value to get the final pulsewidth. This value is unique to each injector and should be supplied by the manufacturer, not calculated or scaled.

The offset becomes very important in idle / low rpm tuning. At idle when pulsewidths are small, the offset is a much larger percentage of the total than at high rpms. If the offset is .5 milliseconds at 14volts and the pulsewidth is only 2.5 milliseconds, the offset is 20% of the total. Compared to only 3% of a 15ms pulsewidth at higher rpms.

Now some will say you can just adjust VE to bring idle fueling back in line, which is true. ... but only for that specific voltage. Once there is a voltage difference (under loads, cruise, idle, etc...) and the PCM uses a different offset, the fueling is off a little again. Get the correct offsets input first, then tune VE and fueling should be very similar under those different conditions.

To take it beyond the normal thinking - You could add a fixed amount of fuel to every pulsewidth by increasing the offset table. In effect, that would make a greater percentage change to idle fueling.

[BigTex]

From my personal experience just last week -

I installed a set of Bosch green top injectors, a set of TEA heads and a new cam. I took my PCM completely back to default values in timing, MAF, VE, idle airflow, etc... I plugged in the new IFR, new offset values, and set idle at 700 rpms. Idling for 10 minutes, one bank showed +1.95 the other was a solid 0. Cruising trim values were between -2 and -4.


For the offset, I found a few posts on the internet referencing the offset values from Ford PCMs that basically matched the post by ChrisB with the values. There seemed to be some confusion as the same offset values were posted for the red top and green top injectors, both claiming to be from the lightning truck. Finally, I hit paydirt and found offset numbers for the green tops that had just been independently tested. The numbers were slightly smaller than those I had previously found, but more than double the original values my PCM had to begin with.

[redhardsupra]

please send me the green top's offset numbers to marcinpohl at gmail dot com
thanks

[Delco]

I have a few comments on this topic and may be completely wrong, but may not...

The way I understand the injector offset, its an adder to the total pulsewidth used to make up for the time it takes the injector to fully open and close. So once the PCM calculates the needed fuel and determines the injector time, it looks up the offset and adds that value to get the final pulsewidth. This value is unique to each injector and should be supplied by the manufacturer, not calculated or scaled.

The offset becomes very important in idle / low rpm tuning. At idle when pulsewidths are small, the offset is a much larger percentage of the total than at high rpms. If the offset is .5 milliseconds at 14volts and the pulsewidth is only 2.5 milliseconds, the offset is 20% of the total. Compared to only 3% of a 15ms pulsewidth at higher rpms.

Now some will say you can just adjust VE to bring idle fueling back in line, which is true. ... but only for that specific voltage. Once there is a voltage difference (under loads, cruise, idle, etc...) and the PCM uses a different offset, the fueling is off a little again. Get the correct offsets input first, then tune VE and fueling should be very similar under those different conditions.

To take it beyond the normal thinking - You could add a fixed amount of fuel to every pulsewidth by increasing the offset table. In effect, that would make a greater percentage change to idle fueling.

True to a degree but hopefully you have a fully functing alternator regualted properly so the voltage the injector normally sees is nice and constant the table is to account for changes in this offset.
Yes GM did a very good job on this part of the calculation and changing the injectors is going to affect it slightly BUT unless yopu have the right test equipment you are going to make the problems worse rather than better.

[MN C5]

A much clearer explaination:thankyou2: I share your understanding of the purpose of injector offset and how the PCM applies the values to the injector signal.

:banana:

lol I thought just explaining how a magnetic coil worked would help:nixweiss:

[joecar]

I thought just explaining how a magnetic coil worked would help:nixweiss: That's fine, your explanation is good :cheers:;
injector does not react instantly;
the coil has inductance, so it's has finite electrical response (which also depends on applied voltage);
the pintle has mass, spring pressure, FPR/MAP pressure difference across it, so it has finite mechanical response to the electrical response.

This table tries to account for this; but how much do we alter this table when changing injectors...? :nixweiss:

And as Delco said, your alternator/regulator is working within limits [hopefully], so at most you'll ever see is a thin stripe thru this table.

[Tordne]

I did actually create a MAP of this table just out of interest and noticed (in my case) that the only columns that were hit were 13.5 and 14 volts.

[hpcubed]

You need to adjust the IFR table and the VE table to get the mixtures right , adjusting the injector pulsewidth voltage table is not the right place to be looking, its a offset for varying voltage and needs some special equipment to get it right

IFR table is known for the given inj. For this test, I am using the maf so no VE correction. I know what the BEN factors are from using the stock inj which gives the error in either my maf or the stock inj. offset table.

When I put the 60 lb inj in and brought the motor up to 2K it would miss (go lean momentarily). When I richened the mixture in my open loop table I did not see the corresponding decrease in AFR meaning the inj. are not opening soon enough to compensate for the slower 60 lb inj.

The inj. offset table is not only an offset for varying voltages, it is also an offset table for a specific injector. So if you are not using the stock inj. then I think that this table may need adjusting.

These 60 lb inj are rated with an opening time of 1.14 ms @14V. Anyone know what the stock inj. turn on time is or the SVOs? This may give a correspondence to the inj offset table.

[BigTex]

....BUT unless you have the right test equipment you are going to make the problems worse rather than better.

Thats the thing, you should get the offset information from a reliable source - either the manufacturer or from a trusted source with the proper testing equipment.

[BigTex]

please send me the green top's offset numbers to marcinpohl at gmail dot com
thanks
I figured you would be interested in the info. Doing my research, I stumbled on many of your posts from several different forums regarding this topic. I'd like to say thank you for digging up as much info about these as you have. Made my work much easier.



Here you go:

6v - 2.55
7v - 2.55
8v - 1.95
9v - 1.48
10v - 1.14
11v - 0.92
12v - 0.75
13v - 0.64
14v - 0.56
15v - 0.49
16v - 0.13

These numbers came from AEM electronics forum. Apparently they will test any customers injectors that aren't in their database. They then add this info to their EMS products install wizard. Read info here:

http://forum.aempower.com/bbs/viewtopic.php?t=11333


For comparison, at 14volts and 0 vacuum, a C5 has a value of .2887 and the green tops have a value twice the size at .56. The previous "known" value for these SVO injectors was thought to be .78x.

Richard

[MN C5]

Edit...Never mind...

http://www.bjacked.net/LuvToHunt/forums/phpBB2/modules/gallery/albums/album01/Beat_Dead_Horse.jpg

[John Skiba]

jfpilla - Any more results?

This is from a while ago but it worked for me:
LABELS Battery Volts {link: GM.VOLTS}
Manifold Vacuum kPa {link: GM.MANVAC} 11.5 12.0 12.5 13.0 13.5 14.0 14.5
0 1.109418 1.033431 0.957443 0.896653 0.835863 0.790270 0.744678
5 1.185406 1.033431 0.987838 0.972641 0.927048 0.942246 0.805468
10 1.185406 1.033431 1.003036 0.972641 0.942246 0.942246 0.835863
15 1.170208 1.033431 1.003036 1.003036 0.942246 0.972641 0.835863
20 1.139813 1.048628 1.003036 1.003036 0.972641 0.972641 0.881456
25 1.200603 1.048628 1.033431 1.003036 0.972641 0.972641 0.881456
30 1.200603 1.079023 1.033431 1.018233 0.972641 1.003036 0.881456
35 1.230998 1.079023 1.048628 1.018233 0.972641 1.003036 0.881456
40 1.155011 1.094221 1.048628 1.018233 1.003036 1.003036 0.881456
45 1.230998 1.094221 1.048628 1.018233 0.972641 1.003036 0.881456
50 1.230998 1.094221 1.048628 1.018233 0.972641 0.896653 0.881456
55 1.230998 1.079023 1.048628 1.018233 0.972641 0.972641 0.835863
60 1.155011 1.079023 1.033431 1.003036 0.972641 0.972641 0.835863
65 1.230998 1.079023 1.033431 1.018233 0.972641 0.972641 0.835863
70 1.246196 1.094221 1.048628 1.018233 0.972641 0.972641 0.835863
75 1.246196 1.094221 1.048628 1.018233 0.972641 0.972641 0.835863
80 1.185406 1.094221 1.048628 1.018233 0.972641 0.972641 0.835863

LABELS Injector Flow Rate (Lbs/Hour)
Manifold Vacuum inHg {link: SAE.MANVAC} Value
0.0 36.954888
1.5 37.202908
3.0 37.450927
4.4 37.636942
5.9 37.884961
7.4 38.194985
8.9 38.318995
10.3 38.629019
11.8 38.753029
13.3 39.063053
14.8 39.187063
16.2 39.497087
17.7 39.621097
19.2 39.931121
20.7 40.055131
22.1 40.365155
23.6 40.489164

LABELS MAF Sensor Calibration (Lbs/Minute)
Hz {link: GM.MAFFREQ} Value
1500 0.188081
1625 0.232518
1750 0.277988
1875 0.327592
2000 0.378230
2125 0.430934
2250 0.489838
2375 0.552877
2500 0.623149
2625 0.702722
2750 0.789528
2875 0.883569
3000 0.982777
3125 1.088185
3250 1.200827
3375 1.318636
3500 1.442646
3625 1.578023
3750 1.725802
3875 1.888048
4000 2.062695
4125 2.245609
4250 2.442991
4375 2.651741
4500 2.872891
4625 3.105409
4750 3.352395
4875 3.608682
5000 3.881503
5125 4.163625
5250 4.463315
5375 4.776440
5500 5.108166
5625 5.462627
5750 5.842923
5875 6.243888
6000 6.666554
6125 7.112989
6250 7.579059
6375 8.069931
6500 8.582504
6625 9.114712
6750 9.671723
6875 10.247334
7000 10.842581
7125 11.459529
7250 12.097145
7375 12.755430
7500 13.438517
7625 14.140205
7750 14.862562
7875 15.609720
8000 16.379613
8125 17.175342
8250 17.995873
8375 18.846373
8500 19.724775
8625 20.632113
8750 21.569419
8875 22.537728
9000 23.534973
9125 24.564253
9250 25.625569
9375 26.718922
9500 27.847410
9625 29.007934
9750 30.204627
9875 31.434390
10000 32.702389
10125 34.003458
10250 35.338629
10375 36.715136
10500 38.128847
10625 39.583894
10750 41.078210
10875 42.620064
11000 44.201188
11125 45.832949
11250 47.508113
11375 49.235981
11500 51.013454
11625 52.845697
11750 54.732711
11875 56.674496
12000 58.678286

Worked for me in the past, but that was a while ago... will let you know if still valid this spring. 32lb Accel injectors. I haven't had much of a chance to play with it over a year+ so these are only for information purposes.

[jfpilla]

IFR table is known for the given inj. For this test, I am using the maf so no VE correction. I know what the BEN factors are from using the stock inj which gives the error in either my maf or the stock inj. offset table.

When I put the 60 lb inj in and brought the motor up to 2K it would miss (go lean momentarily). When I richened the mixture in my open loop table I did not see the corresponding decrease in AFR meaning the inj. are not opening soon enough to compensate for the slower 60 lb inj.

The inj. offset table is not only an offset for varying voltages, it is also an offset table for a specific injector. So if you are not using the stock inj. then I think that this table may need adjusting.

These 60 lb inj are rated with an opening time of 1.14 ms @14V. Anyone know what the stock inj. turn on time is or the SVOs? This may give a correspondence to the inj offset table.

HP
Mine are 30lb SVO's and I'm finding the table slopes opposite of the stock table. Your big Injectors are probably more extreme.
You make, I think, a good point about needing adjusting for different injectors. If we install injectors that require a different offset table and we don't adjust the IOS then aren't we in affect keeping an incorrect offset table or am I off base?
Joe?

[redhardsupra]

i think you're completely on the money. if it's not perfect, it's wrong :)
so what i'm thinking to eliminate the posibilities of screwing up is to install a fuel regulator that will keep it perfectly flat. this way the whole table looks like the static value, which is one of the few pieces of data we actaully get with the injectors.
is this a proper 'runaround/possible problem eliminator' for something like this?

[BigTex]

My truck has a fuel pressure regulator on the rail. It takes a lot of guesswork out of injector tuning.

[joecar]

is this a proper 'runaround/possible problem eliminator' for something like this? It seems to me that F-body and Y-body are the only vehicles without one, everyone else has one.

If installing one, you'll also need to run a return line.

[TAQuickness]

i think you're completely on the money. if it's not perfect, it's wrong :)
so what i'm thinking to eliminate the posibilities of screwing up is to install a fuel regulator that will keep it perfectly flat. this way the whole table looks like the static value, which is one of the few pieces of data we actaully get with the injectors.
is this a proper 'runaround/possible problem eliminator' for something like this?


Got any ideas on how to calculate a correction?

[hpcubed]

Well I did some more tweeking last night. Seems for my application 60lb mototron inj. like a little more offset at idle and small throttle opening. This gets rid of any miss and gives a decent BEN. The other points seem pretty close using the stock setting. When i increase all the points in the same ratio as stock, the car runs more rich and is sluggish. I need to fine tune some more. This indicates that the mototron inj are pretty fast for a big inj. They don't work well with the stock offset at very small pulse widths. I would still like to see the correct numbers for these inj. I did notice that when I increased all the cells, the AFR ratio was extremely stable - but rich.

And yeh, maybe a vacuum ref. regulator may make tuning these big inj. a bit easier. (Already have onewaiting to go on)

[oztracktuning]

JfPilla
Can you share your SVO 30 table values?
Im still interested in seeing if i can get the voltage variations matched up better.

[jfpilla]

JfPilla
Can you share your SVO 30 table values?
Im still interested in seeing if i can get the voltage variations matched up better.

Sure, but it's not really ready.

[John Skiba]

Quick note before everyone goes off and ends up getting frustrated with the tuning of this table...

The injector data that I've seen for various injectors(manufactures, et) follows a similar curve. With that being said, this table shouldn't vary much from the stock table across the board. (Hint, when you do a % compare in EFILive on the table compared to stock your graph should look near flat IMO)

If you tuned your VE table and then try to tune this table, forget about it. Your probably done. You've probably made life for youself exponential more difficult. Same goes for any other table that affects fueling. Start with the stock knowns.

Keep it simple, the change shouldn't need to be drastic. (see my table above) Delco put it best in his post. Don't get wrapped up chasing your tail with another new table or the hype around the table. KISS

Example: Here's how it worked for me... I knew the ZO6 MAF table was correct (stock - after all GM spent massive $$$ to nail down the MAF flow characteristics in a C5), I knew the IFR table was correct (again - the math for stock injectors confirmed this and actual injector flow #'s for others confirm math). So, why was what I was commanding in PE not matching what I was seeing on the WB??? Partially, VE I'm sure. How, the characteristics of the injector are different also. Thus my quest began. Thanks to Chris B for the extrapolation math and the real data from a ford vehicle, born was a new offset table. Is it 100% accurate? Don't bet you life in it. Is it more accurate then stock... hell yeah, I peronally believe it to be based on the results... well, lets just say, what I command in PE is what I GET out through the tailpipes (Wideband) and always repeatable. At this point, I didn't even TOUCH the PE table, my WOT ltrims are 0 and my ltrims all together ranges from -8(very few) to +3 .

Either this worked out way to SIMPLE for me or I'm going crazy. I can't wait to VE tune. I don't think my VE table change will be drastic. What do you guys think? ;)

Anyone else do it this way? I'm not telling or suggesting to anyone that this is the way it should be done, merely sharing what worked for me based almost solely on given GM data and math over 2 years ago. Besides, I to lazy to guess at table # and flash the car hundreds of times when if all is right the math should work.

[John Skiba]

opps... I did say quick note... :bash:

:beer:

[jfpilla]

John,
The VE suggestion sounds good. I'll try it for sure.
Joe

[jfpilla]

Got any ideas on how to calculate a correction?

Would like to know also.

[Tordne]

I created a custom PID some time ago that turns the LTFT values into a factor similar to BEN that I could use as a multiplier.

Could that work? Using a sort of multiplier against the current Voltage Offset table as sort of a error %?

[jfpilla]

Next file.

[jfpilla]

another one.

[jfpilla]

I created a custom PID some time ago that turns the LTFT values into a factor similar to BEN that I could use as a multiplier.

Could that work? Using a sort of multiplier against the current Voltage Offset table as sort of a error %?

I'd try it. The biggest problem is logging volts. There's no way to control voltage and log them sufficiently. It looks like lots of extrapolating.

[hpcubed]

I created a custom PID some time ago that turns the LTFT values into a factor similar to BEN that I could use as a multiplier.

Could that work? Using a sort of multiplier against the current Voltage Offset table as sort of a error %?

You will be combining all of the data for each map range and condensing it into one cell so there could be some error as your BEN is probably not 1 across the board. But it will give you an idea. One thing I looked at was the difference between the BEN factors between 13.5V and 14V for the same map values. Not how far the BEN was from 1.00. Only the difference. I think this is useful and got my BENs a lot closer.

Initially i used the maf and scaled the offset table so I had similar BEN values that i had with my stock injectors. I had to increase mostly around idle and not much at WOT.

[TAQuickness]

You will be combining all of the data for each map range and condensing it into one cell so there could be some error as your BEN is probably not 1 across the board. But it will give you an idea. One thing I looked at was the difference between the BEN factors between 13.5V and 14V for the same map values. Not how far the BEN was from 1.00. Only the difference. I think this is useful and got my BENs a lot closer.

Initially i used the maf and scaled the offset table so I had similar BEN values that i had with my stock injectors. I had to increase mostly around idle and not much at WOT.


Now that's a good idea...

[jfpilla]

Now that's a good idea...

It looks like you got your wish. The attached was done with the MAF so it's not accurate. I was interested in seeing the values it would produce. It should be done in SD. Any thoughts on what comes first?

-VE's back to stock.
-IOS adjusted.
-VE's

[hpcubed]

It looks like you got your wish. The attached was done with the MAF so it's not accurate. I was interested in seeing the values it would produce. It should be done in SD. Any thoughts on what comes first?

-VE's back to stock.
-IOS adjusted.
-VE's

Those look pretty good already just need a little tweeking. I would adjust the IO's with the maf in open loop, then go to speed density and adjust the VE's. Don't really need to put the VE's back to stock.

One question is how accurate is the stock offset table for the stock injectors. Assuming that it is very accurate, I think the way to do it would be:

1. Log BENs with maf in open loop using stock inj. If you have old files saved with this data you could use that.
2. Log BENs with maf in open loop using new inj.
3. Adjust inj. offset so that new BENS match old BENS. Obviously everything is not going to match perfectly. This effectively divides out the error in the maf.
4. Go to speed density and start the tuning process.

[jfpilla]

Those look pretty good already just need a little tweeking. I would adjust the IO's with the maf in open loop, then go to speed density and adjust the VE's. Don't really need to put the VE's back to stock.

One question is how accurate is the stock offset table for the stock injectors. Assuming that it is very accurate, I think the way to do it would be:

1. Log BENs with maf in open loop using stock inj. If you have old files saved with this data you could use that.
2. Log BENs with maf in open loop using new inj.
3. Adjust inj. offset so that new BENS match old BENS. Obviously everything is not going to match perfectly. This effectively divides out the error in the maf.
4. Go to speed density and start the tuning process.

1. Log BENs with maf in open loop using stock inj. If you have old files saved with this data you could use that.
>>>>That's out.

2. Log BENs with maf in open loop using new inj.
3. Adjust inj. offset so that new BENS match old BENS. Obviously everything is not going to match perfectly. This effectively divides out the error in the maf.
4. Go to speed density and start the tuning process.
>>>>I don't get the point of logging in open loop then tuning in SD?

I've established an offset table using ltft's vs volts and manvac and the stock VE table. You mentioned using Ben's so I tried it to see what kind of values would be returned. The results seem accurate but whenever the AFR changes enough it's obvious that trims affect these results making the results look decent since the AFR is being maintained by trims. It looks as if there are two ways to do this. 1) Set up the offset table by ltft's. This is very tedious. 2) Go into mafless mode and use BEN's.
What I don't know is if the VE table should be stock when doing offsets. VE's should be done with correct IFR's. If the IOS's are wrong then the IFR's are wrong. It sounds like I'm going around in circles and that's how I feel. Any opinions on my thinking are encouraged since I'm a little lost as to what to go at first. I guess I can do the offsets using BEN with a stock VE table in SD and see what I get. It would seem that if the offsets come into line then the VE table should also be close. I'd better save my current file since the car is running great with it.

[hpcubed]

1. What you suggest should work. But I would rather use a wideband than trims so that is why I suggest using the BENs (and open loop).

2. My suggested steps utilized the stock inj and maf because we need a known to compare to. And by doing it the way I suggest, the error from the maf is divided out. Since you can't do this in your situation. So you have to either accept that what your maf is saying as a known or the VE table. I would think the maf is more correct right out of the box - so to speak.

3. You set up your table as you suggested either using BENS or trim. However the value in your table for 1 cell is condensed down from the values of trims from all rpms for a given map. If they are all the same value then bingo if they are all over the place you have to use some judgement.

[jfpilla]

I've already done it by trims. It will be nice to do it by BEN and have them match what I've done, closely.
Thanks for the input.

[oztracktuning]

I just had another go with the voltage offset table - this time i just changed the cells to suit the situation. The issue is i have used the IAT correction tables in the custom operating system to get the afrs consistent in different IAT and it is almost there....however the problem is that idle is still not cooperating and its leaning out when the IAT is hot but its not consistent with IAT temps ie. at the end of a long drive it is lean idling even when the IAT temps are lower than 30min before when the IAT temps were higher.

I think the issue is lower battery voltage after the car is driven for a while. Early in the drive its nearer to 13.4V at idle most of the time but when driven and hot its closer to 13.0V at idle and sometimes lower especially when the idle is erratic. I think leaness at idle is causing the erratic idle - it seems to be the main thing that is different ......so to fix it or at least i will find out tommorrow - i have just added a little extra offset in the cells that are used at idle in the voltage offset table , in the 11.5, 12.0, 12.5, 13.0 V columns. I added 0.08 in the 13.0V and 0.10 in the others. This should effectively richen things up a bit when the car goes lean at the end of long drives at idle

As i said earlier when moving and voltage is up a little higher the afrs at the end of a long drive are well sorted its just at idle things arent quite good all the time.

Currently im logging a 45min trip to work and trimming the tune and then logging on the way home. It makes the trip fun :thankyou2: EFIlive.

[joecar]

Currently im logging a 45min trip to work and trimming the tune and then logging on the way home. It makes the trip fun :thankyou2: EFIlive.
Makes your breaks at work fun too... :cheers:

[jfpilla]

This worked for me.

Calc. IFR and use stock MAF table.

With MAF.
Set up a MAP to log LTFTs_MANVAC_BATVOLTS and adjust these ltfts using IOS table. The VE's have no affect so you can keep what you've done. You can stop here. I like my VE's tuned even though I run the MAF.

MAFLESS.
Either do the above step first or if you don't have your maf installed do an autotune or keep your VE's if already done. Only adjust VE's to the point that DYNAIR matches MAF logged values. This will account for any incorrect IOS numbers. Then log IOS using BEN_MANVAC_BATVOLTS and adjust IOS.

I'm really pleased that the only tables now not stock are ETC and Startup Friction Airflow Correction. Probably due to having a 90MM TB.

[oztracktuning]

Its offtopic - but here is a music video of the trip i made for a bit of fun. Its on the outskirts of Sydney where much of it is still farmland. http://www.athleticstraining.com/carsnew/fasthawk.wmv

[TAQuickness]

jfpilla - Somehow I lost my train of though in this thread... Need some help to make sure I'm on the right page again.

Adjustments to the IOS are based on the difference in LTFT's or BEN's from one voltage/man_vac range to the next (column to column). If we're thinking the same thing, this part makes sense to me.

What's loosing me is what to use as the starting point. seems we would need at least one column of known good IOS offsets to use as a control.

[jfpilla]

jfpilla - Somehow I lost my train of though in this thread... Need some help to make sure I'm on the right page again.

Adjustments to the IOS are based on the difference in LTFT's or BEN's from one voltage/man_vac range to the next (column to column). If we're thinking the same thing, this part makes sense to me.

What's losing me is what to use as the starting point. seems we would need at least one column of known good IOS offsets to use as a control.


It does appear that it's easier if you start using the MAF to get a decent IOS table. The option without an MAF is to set VE's to the point that the MAFgms and DYNAIRgms are close. That will get the AFR to a point and the difference is made up by setting the IOS table. The Offset Ben Map will get you there.
My IAC DES., DYNAIR and MAF numbers fell right in line.
It was magical.:banana:

[joecar]

Its offtopic - but here is a music video of the trip i made for a bit of fun. Its on the outskirts of Sydney where much of it is still farmland. http://www.athleticstraining.com/carsnew/fasthawk.wmv
Flyer,

Cool video, looks familiar, where exacltly was it shot...?

Joe:beer:


Edit: We're sorry to hijack the thread, we're attention challenged... :wave:

[oztracktuning]

Blue Mountains to M4 then through Penrith and out Castlereagh Rd to North Richmond and beyond about 10min. Its a nice simple drive. In the mornings its been 25deg C and in the afternoons its been hot 33 deg C. Good variation for logging. But in winter it will be cooler and quicker!

[oztracktuning]

My log today was a success - it seemed to help. I logged voltage and created a chart with rpm and afr and it seemed to show a good change.
Its certainly better parking up my driveway now when its hot. So i think this table is a good thing.

As soon as it has any lean afrs up near 15.0 at all when idling - the idle quality deteriorates.

[TAQuickness]

this might be of some help/interest
http://www.ls1tech.com/forums/showthread.php?p=4573309#post4573309

[ringram]

Hi Joe, just sent an email, any chance you want to share your latest offset table?
Ive just installed the svo 30's and have noticed stuff is out a bit.

Many thanks,
Richard

[redhardsupra]

ringram: just use my spreadsheet, i used it for my svo 30s, punched in the numbers and it's been that way ever since. works perfect

[ringram]

I used your table for IFR, but didnt realise it did IOS as well..?

[redhardsupra]

oh the OTHER offset... sorry ;) it doesn't do that one, i just use the stock one from 26.4 setup for that, and trims came back right about perfect after the swap

[ringram]

Ok cool. Ill see if Joe can share what he has, otherwise Im running an earlier one posted in this thread. Just want to make sure things are as nice as possible before tuning up again. It was pretty close till I put in the new t'stat and drop the temps and messed with spark advance... now the tune is all out, so just wanted to get the offsets right so that fueling was bang on going forward.

[jfpilla]

Hi Joe, just sent an email, any chance you want to share your latest offset table?
Ive just installed the svo 30's and have noticed stuff is out a bit.

Many thanks,
Richard


Email me.