WOT aft and timing

[maudyZ28]

OK,

after a run at the strip I reverted back to my stock PE vs rpm of 11.7 all over, previously I commanded 12.6 but it started to knock a bit at the top end of the revs so it was leaning out or timing was too advanced.

Im going to do more logging and a VE after my headers but wanted to get a bit of theory straight, which would be best vs stock timing and fuel at PE

1: PE vs RPM to richen from 12.6 to 12.2 and leave stock timing (still rich)
2: PE vs RPM to be 12.6 across the board and reduce timing from 4000 rpm by 2 deg
3: PE vs RPM to go like 13.2 to 12.8 and run 2-3 deg less timing everywhere or similar to a LS6 Z06 spark table

Basically from what I understand, the idea mix is 12.8-12.6 afr, and then you advance timing to suite (if i had a dyno). But the stock trim runs 11.7 and like 27.5-28 deg at WOT @ 4000 rpm (ish) is this just to make the over rich mixture burn more completely as there is more time for it to burn, but actually doesn't yield any power due to it been overly rich. SO I would get more power from a leaner mix closer to 12.6 with less than stock timing?

[WeathermanShawn]

MaudyZ28:

You being a scientist..This is pretty good reading.

http:///www.innovatemotorsports.com/resources/rich.php (http://www.innovatemotorsports.com/resources/rich.php)

http:///www.innovatemotorsports.com/resources/myths.php (http://www.innovatemotorsports.com/resources/myths.php)

I like their approach. I use a flat 12.7 AFR (easier to hit Commanded with one EQ number..1.152 ) and work on spark to eliminate KR. Every car is different, but 99% of the time I eliminate any KR with spark retard and not more fuel.

Just an opinion, but Innovate really digs into the application of it.

Cheers..

[maudyZ28]

thanks Shawn (ok to call you sean?? im Luke btw)

Thats essentially what I wanted to know, reduce timing and fuel from stock = more power. I might just use the LS6 Z06 spark table and see how it goes. Need to dial in a better VE though.

I assumed stock timing was high to help burn more fuel as it was a super rich mix

I do some bedtime reading, I need to concentrate at work now but keep reading tuning stuff :(

[WeathermanShawn]

Hi Luke:

You can call me Shawn (my Mother liked it) or Weatherman..or WeathermanShawn.. True, we may not be very popular after the Icelandic Volcano, but Weather is still my main passion and occupation (I am very lucky).

As long as you don't call me any names, you can call me whatever you like. I do prefer the Shawn spelling though..

Are there that many F-bodies in your area, or is yours 'one of a kind'?
Have fun tuning!:cheers:

[maudyZ28]

cool, sorry i put Shawn and then Sean too, but it will be Shawn from now lol

Well in the UK there are not that many f-bodies, its unusual to see more than about 4 more at an event. Then there are even less who modify there cars. Plus im from the north of UK and there is literally about 2-3 american specialist up here and the majority of the money and cars are in the south, London area etc

I like to think my camaro is one of a kind, got a few good comments this weekend at the races so that was nice :D

It good your weather is you job and passion, im currently in a phd studying massive star formation but just getting into it but find myself not being bothered sometime, which is bad. I'll keep at it and see how it goes

[5.7ute]

OK,

after a run at the strip I reverted back to my stock PE vs rpm of 11.7 all over, previously I commanded 12.6 but it started to knock a bit at the top end of the revs so it was leaning out or timing was too advanced.

Im going to do more logging and a VE after my headers but wanted to get a bit of theory straight, which would be best vs stock timing and fuel at PE

1: PE vs RPM to richen from 12.6 to 12.2 and leave stock timing (still rich)
2: PE vs RPM to be 12.6 across the board and reduce timing from 4000 rpm by 2 deg
3: PE vs RPM to go like 13.2 to 12.8 and run 2-3 deg less timing everywhere or similar to a LS6 Z06 spark table

Basically from what I understand, the idea mix is 12.8-12.6 afr, and then you advance timing to suite (if i had a dyno). But the stock trim runs 11.7 and like 27.5-28 deg at WOT @ 4000 rpm (ish) is this just to make the over rich mixture burn more completely as there is more time for it to burn, but actually doesn't yield any power due to it been overly rich. SO I would get more power from a leaner mix closer to 12.6 with less than stock timing?

maudyZ28 how is your commanded versus actual AFR from a wideband on the track?
The general rule is timing is lower around peak torque & then ramped back up in the higher RPM band. Running a leaner AFR will only result in a few extra HP & IMO is not worth the risk in an everyday driver.(unless you can verify that you are not on the knock threshold with a dyno, knock phones etc)

[maudyZ28]

hi 5.7ute,

I dont have a wide band, hence just changed one thing at a time, did a run and see the out come. There were like 4 points in the log file where the car knocked, upto a max of 5 deg was timing was pulled in 3rd gear at 4000rpm (worst) just as the MAF takes over right? Or is the MAF fully incharge on WOT.

I understand how the timing ramps, goes from like 24-28 deg on stock tune from about 3500-6000 rpm. My issue was that the commanded AFR is 11.7 which is clearly far from optimum. Essentially I reduced this to 12.6 commanded to see if I got knock, which I did but only 2 deg in 3rd, again at 4000rpm. So I richened it to 12.45 and the knock was WORSE, so it appears that this is actually burning faster (i really want to know how it relates to real AFR) for the same timing and knock was 5 deg as above. Basically I am now going to reduce the timing with AFR at 12.45. The innovate links Shawn posted are really useful, basically less fuel and timing gets similar or more power (a few hp like you say) than rich and more timing. And I would prefer to run less fuel and timing to achieve the same goal as super rich more timing

One question again (not at WOT just driving normal), say when running MAF only (enable at 400 rpm so that is the only thing controlling fueling right?) if I command 14.63 and a WB says it is leaner or richer, even though everything else is the stock tune does this point to incorrect MAF calibration OR incorrect injector rates OR the O2 switch point being off so adjusting trims??? I assume the latter with the O2s so I would change these such that I get a roughly stable 14.63 as I would assume the MAF and IFR are correct, or are the O2 best at 450mv as was mentioned before??

[WeathermanShawn]

Maudy..Luke:

I will let 5.7ute explain all the intricacies of the airflow contribution from MAF/VE and resulting injector flow. With the airflow calculation of MAF set at 400 Rpm and in closed-loop you will be adjusting the MAF frequencies vs airflow (g/s) to correctly model the airflow.

If you adjust the Injector Flow Rate (frowned upon) your MAF airflow (CYLAIR) and DYNCYLAIR (SD) will never match. You will erratic fueling upon transient and widely swinging Trims.

It is best to achieve a harmonious MAF and VE Table airflow. If you do it open-loop try the AUTOVE method. If you prefer closed-loop with the narrowbands trimming and you are keeping your MAF, you might try WeathermanShawn's Tutorial method to calibrate MAF, VE, and Trims simultaneously. I have linked a short but precise link that Joecar wrote that really explains the difference..http://forum.efilive.com/showpost.php?p=119640&postcount=21..

The wideband becomes essential to tuning both for closed-loop and for verifying Commanded AFR vs actual during PE Mode and WOT. It only takes a about 4-6 seconds to detonate an engine..there is no other reliable method to verify your fueling under load.

The instructions on O2 switch-points is more of a suggestion to make closed-loop tuning a little more precise. For your purposes I would keep the O2 switchpoints stock. It has a minimal effect on your actual AFR's. It is a Tutorial method only.

Hope that clears it up a little. I have simplified the process. 5.7ute and others can tell you all the precise contributions..but that is the 'cliff-note' version..

[maudyZ28]

thanks again Shawn, im at the stage where I understand it but need more info on what car is doing, IE WB !!!!

Think I'll just do your calcVE again and leave the rest till I get the WB, kinda spent a lot on EFI live £600 and WB is another £150 :shock:, I could have just bought a stall converter and cam and let the car run crap hahah. plus its really hard to do the VE tuning on the street with an A4 with 2.73 highway gears!! Have to run about in 2nd gear between 0-160km/h

How do you think headers will affect the response of the O2 sensors, or will they be ok still at stock value?

[WeathermanShawn]

Luke:

Some people still run stock setting O2 switchpoint setting with headers. I experimented with a range of 400-550 mv and tried to align up a mv reading to my B3601 of 14.63 AFR. I settled on 550mv across the board. I do not necessarily recommend that setting to everyone..but thats where I ended up.

You will have to experiment...

Regards..

[RevGTO]

The stock 99-00 timing tables are pretty aggressive in the peak torque range of 4000-4400rpm. I would routinely see max KR at the track running about 13.0 Richening up to the mid 12's didn't help much. So I backed a few degrees of timing out of the affected cells. That and bringing the octane up a bit takes care of all of it, so I can run my preferred 13.0 with zero KR.

[5.7ute]

hi 5.7ute,

I dont have a wide band, hence just changed one thing at a time, did a run and see the out come. There were like 4 points in the log file where the car knocked, upto a max of 5 deg was timing was pulled in 3rd gear at 4000rpm (worst) just as the MAF takes over right? Or is the MAF fully incharge on WOT.

I understand how the timing ramps, goes from like 24-28 deg on stock tune from about 3500-6000 rpm. My issue was that the commanded AFR is 11.7 which is clearly far from optimum. Essentially I reduced this to 12.6 commanded to see if I got knock, which I did but only 2 deg in 3rd, again at 4000rpm. So I richened it to 12.45 and the knock was WORSE, so it appears that this is actually burning faster (i really want to know how it relates to real AFR) for the same timing and knock was 5 deg as above. Basically I am now going to reduce the timing with AFR at 12.45. The innovate links Shawn posted are really useful, basically less fuel and timing gets similar or more power (a few hp like you say) than rich and more timing. And I would prefer to run less fuel and timing to achieve the same goal as super rich more timing

One question again (not at WOT just driving normal), say when running MAF only (enable at 400 rpm so that is the only thing controlling fueling right?) if I command 14.63 and a WB says it is leaner or richer, even though everything else is the stock tune does this point to incorrect MAF calibration OR incorrect injector rates OR the O2 switch point being off so adjusting trims??? I assume the latter with the O2s so I would change these such that I get a roughly stable 14.63 as I would assume the MAF and IFR are correct, or are the O2 best at 450mv as was mentioned before??

Airmass prediction is taken from the VE table until the RPM threshold of B0120 is met. (Stock 4000 RPM) The maf is still used as a sanity check. Once B0120 is reached, in a steady state, the Airmass calculation is taken solely from the maf. In a transient condition there is some tricky use of the maf, VE & transient tables which I have not fully nutted out yet.
Enabling the maf only at 400 RPM will cause some fuelling discrepencies at low engine speeds as airflow is erratic due to reversion.

Now, while commanding 11.7 AFR you may have only had an actual AFR of 12.8 AFR. Once you lowered commanded AFR to 12.6 your actual may have still been well over 13.2 AFR, causing the KR. Enrichening commanded to 12.4 would still be leaving you too lean at peak torque, again a wild guess at 13.1 AFR. One thing to ponder is that a certain AFR will give you a fast burn. Richer or leaner from this mixture the burn will be slower & less prone to knock. (I cant remember where I got this info from but I will chase it up) I believe this is happening in your case as a slight enrichment is making the engine more prone to knock. (A rich mixture can also cause knock, but without wideband verification this is all conjecture)
Post some logs if you can.

[N0DIH]

Here is the stock L67 Supercharged R/L Threshold.

http://i159.photobucket.com/albums/t142/mompower/Tom/PCMTuning/SC3800RLThresh.jpg

It is interesting, it isn't allowed to switch until it gets well past 450 on the rich side. And despite being 500mV on the low, it swings well past....


Luke:

Some people still run stock setting O2 switchpoint setting with headers. I experimented with a range of 400-550 mv and tried to align up a mv reading to my B3601 of 14.63 AFR. I settled on 550mv across the board. I do not necessarily recommend that setting to everyone..but thats where I ended up.

You will have to experiment...

Regards..

[WeathermanShawn]

Wow, I really like that table & display. Our OS goes by 'Closed-Loop' Modes which are related to airflow (g/s).

That display really looks user-friendly. Is that yours or EFILive's?

Anyway, thanks for sharing. Very interesting..

[N0DIH]

That is TunerCat OBD2. I have EFILive Scan, not Tune yet. I use Tunercat for Roadrunner tuning. It rocks.....

LT1's have modes and switchpoints. 3800s don't have the CL Modes for it. The LT1's do IIRC (my 94 did)


Wow, I really like that table & display. Our OS goes by 'Closed-Loop' Modes which are related to airflow (g/s).

That display really looks user-friendly. Is that yours or EFILive's?

Anyway, thanks for sharing. Very interesting..

[maudyZ28]

thanks guys, I looked at the Z06 2001 tune and the O2 points are at 525, even the 1999 corvette C5 are different to the camaro, different sensors I presume?? anyway i digress

5.7ute, the 'innovate' link before that Shawn posted explains the fuel mix thing. Lean or rich burn slower and the best AFR is between 12-13.

Basically on 11.7 stock tune, no knock as expected
Change to 12.6 and get a 'small' amount of knock'
So i richen it to 12.45 and get MORE knock (must in fact be burning faster here, more optimum burning mix) still don't know what it really is (and had all O2 points at 450mv then)

I am going to change it to this and reducing timing by 3-4 deg and see how the car drives. Need to wait till next track day (3 weeks) and i'm competing too in a bracket series and my times are far from consistent, i can get power down on street tires :(

When doing the calc VE i enabled my MAF at 400rpm and the car ran quite well but i was driving very steady no raid throttle changes. Does it still try and use VE here if not in a steady state?? Also steady state means constant air flow so how above 4000 rpm is it steady state?? it cannot be because the MAF airflow ramps with rpm as more air comes in??

[WeathermanShawn]

When doing the calc VE i enabled my MAF at 400rpm and the car ran quite well but i was driving very steady no raid throttle changes. Does it still try and use VE here if not in a steady state?? Also steady state means constant air flow so how above 4000 rpm is it steady state?? it cannot be because the MAF airflow ramps with rpm as more air comes in??

If B0120 is set to 400 rpms, then the airflow from the VE Table is essentially ignored. It is using MAF calculated airflow (g/s) regardless of Rpm or steady-state. The concept with CALC.VE Table is that the airflow calculation from MAF when applied in that extensive Formula that Joecar worked up, is to calculate the dynamic airflow solely from the MAF and LTFT corrections.

Then when you are through, your MAF-derived Airflow and dynamically-derived airflow are essentially comparable. So after you complete the process, all your steady-state and transient airflows are in unison.

The 4000 Rpm threshold is a separate topic. It is not really applicable when you have it set to 400 Rpm. From the factory the 4000 Rpm threshold is as you stated. The amount of airflow at those Rpms are considered reliable enough to use the MAF exclusively.

It is very easy to confuse differing tuning methods while utilizing a method. The CALC.VE Table Tutorial is for those tuners who wish to utilize MAF-Closed-Loop. The resulting VE Table is reasonably accurate. While it is a natural instinct to think things through, it would be very easy for someone to miss a vital step.

If you do it correctly, your LTFTs, MAF Calibration and VE Table will be accurate. You will know it when your Trims average near zero, your Commanded Fuel in stoich and PE Mode match. Your CYLAIR.DMA and DYNCYLAIR.DMA Pids that you selected will rapidly converge to the same units. Normally by the 2-3rd log this occurs.

In some ways you just have to do it. Do it too fast or not reading the entire Tutorial will be self-defeating. With a wideband and functional narrowband sensors, you should be able to do this in an afternoon.

I would just slow down and make sure you do all the steps. Then it will make sense. It is hard to pack all of this in a Tutorial, but in essence all the remarks I have here are in the Tutorial.

Get that wideband and it will be a lot more productive tune..:)

[tor1965]

Is it so that if I am following the CALC.VE Table Tutorial it will let me tune in both the ve table and the maf table even if they are way out to start with?

[maudyZ28]

thanks again Shawn,

Im just trying to get in my head what runs what, I posted another topic about VE tuning without the MAF but using VE table exclusively.

I also wish I had a dyno :sly: it would make it sooo.. much easier. I think 3rd in auto is best to get a nice MAP but that goes from 0-160 mph, so I use 2nd which is still 0-100 mph capable as i probably look quite strange speeding up and slowing down and accelerating smoothly etc not to vary the throttle too fast. More logging needed, ill have to go on an epic drive :) Do you recommend Loading the car with the brakes??

tor - yeah start with a stock tune and assuming car has stock injectors etc you dont need to change anything. Go for a dive and log the PID and MAPs as per Shawn's tutorial. Make sure you have that calc_pid file. It uses the LTFT as the BEN factor if you dont have a wideband if you do then use it as a check to see how LTFT behave. Then correct the MAF frequencies and VE table to suite. The idea is using the MAF to measure the air flow to calculate how much the engine is asking for ad there by correct the VE table to match the MAF. I think also if you exclusively run the MAF and then correct it, the BEN factor will be one, such that the MAF freqs are correct. I'm sure Shawn can help you out if I havent explained it right, but thats how I understand it.

[joecar]

See my profile page (click on my username at left) for summary/cheat-sheets

[WeathermanShawn]

Is it so that if I am following the CALC.VE Table Tutorial it will let me tune in both the ve table and the maf table even if they are way out to start with?

Tor1965: Yes. I have seen one user who in the course of 3 logs take a VE Table, MAF Calibration, and Trims to perfection. They all 'converged' quite nicely.


thanks again Shawn,

Im just trying to get in my head what runs what, I posted another topic about VE tuning without the MAF but using VE table exclusively.

I'm sure Shawn can help you out if I havent explained it right, but thats how I understand it.

Thanks Luke..I think you have it down. I agree, street tuning has it challenges. Whichever route you go..it is all good learning along the way..


See my profile page (click on my username at left) for summary/cheat-sheets

Guys and Gals.

Joecar has some really good 'cheat sheets' along with a lot of good tuning information. Remember, my first four months of tuning as a beginner I bounced around too. The Tutorial was written from that perspective. There is no substitute for reading, research and a lot of logging. Hint..Even to this day very few tuners understand exactly the precise contribution of VE Table and MAF airflow at every RPM, MAP, and MAF frequency for every TPS % you drive at...It takes a lot of math and computer code knowledge to know. Until then, you have to try various methods and see which one works for you..

:cheers: