Tuning Gremlin! System Stability Issues. Any Ideas or thoughts?

[mufreq]

I have been trying to tune my car, but am having some very flaky responses when changing parameters. I had KC Maxx in KC help me over the weekend thinking that I may be doing something wrong, but Ryan had similar issues and had never seen anything like this before...so looking for any help/input before buying a new ECM.

Here is what I have for a config....

General setup is Trailblazer LS2 6.0L
E40 - out of a 2006 GMC Envoy 5.3L
LS2 DBW
2006 MAF/MAP/Crank/rear mount cam sensor
2010 camaro downstream o2 sensors
LS3 Intake/Injectors/Heads
XER273HR-14 224/230 dur@50 581/588lift
T-56 trans

Symptoms;
No errors or codes from any of the sensors.
MAF frequency readings align with what Ryan expected.

Started off with a typical GTO LS2 parameter set on the dyno; car would not make any power, fueling was sporadic fluctuating mostly lean and would die when going to neutral on dyno after pull. The car acted like it was in limp or power reduction mode from traction control or something like that.

Made a slight change in MAF and fueling tables, performed calibration update; when starting up you could tell that the system was working right. Made a full pull to 6500. MAF HZ looked good, AFR was linear, and no KR.

Adjusted MAF table 5%, fueling table to lean out some down low and richen up on top end, performed calibration update; system went abnormal again exhibiting same characteristics. (Nothing else was changed)

Tried loading the same settings with full write to ECM, no joy - same behavior. Any slight changed makes the systems unstable.

Reverted back to the previous file we were able to make a full pull on; as soon as car started the system was working properly and was able to make a full pull. Then when we pulled car off dyno to load back on trailer, the car started misbehaving again. Turned car off, started it again, and it cleared up...weird!!!

I have yet to fully confirm grounding issues, but will once I get the full pin-out on the harness.

Could it be the base OS on the ECM causing the issues? If so, could reloading base SW with Tech2 fix it or is it best to get a different ECM?

Many Thanks!

[schpenxel]

Need copies of tune/log..

Most us have noticed weird fueling right after a flash, not sure if this is that issue or something else though.

[mufreq]

Here are two sets of files, one from the clean pull and the other setting in the shop exhibiting the fueling issue.

I am fairly new to the logging scene with HPT, so if I need to capture something that is a must have I am learning! :-)

Thanks!

[schpenxel]

I literally don't see a "pull" in either of these logs. Just a bunch of blipping the throttle for half a second here and there

It's def. lean in the "with issues" log, the NB O2 sensors are going lean, so it's leaner than 14.7:1.

I'd make the tune either all MAF or all SD. Right now it's in mixed mode. Tough to tune MAF and VE at the same time.

29* spark seems kind of high to me. Stock LS2 Corvettes are like 18-19*. Probably will take more, not sure I'd start out at that high though.

Add intake valve temp and injector tip temp to list of channels. I'll try to look at the logs more tomorrow, time go home!

[mufreq]

Thanks - I will try to capture some driving logs with IVT and ITT soon...raining here today and possibly all week! ugh - way too much rain this spring so far.

If you look at the log "pulls clean with dyno..." that file was from the dyno pull. The variations are due to shifting up to 4th gear, then you see in the last 20% of the file it is the actual WOT pull.

We did try to go into full SD mode, per an e40 white paper process I pulled down from HPT site here, however there was a tip in fueling issue we couldn't figure out so we went back to the standard setup to see if we could get it to stabilize out. If you have a reference on how to MAF only tune, I will definitely try that process to see if I can make headway there.

Also, given my novice level, are there any standard embedded channels or user defined channels I should be capturing to better log and assess what is happening?

Many Thanks!

[schpenxel]

Yeah, transient fueling does go a bit weird when running SD, especially at first. It's usually not that bad to tune around, but I still have a slight lean tip in on mine too

To go 100% MAF just set dynamic airflow disable to a low RPM

engine-->airflow-->dynamic, set disable to say 200 RPM's and enable to 100 RPM's. That will make it only use the MAF for airflow calcs

[mufreq]

OK - I set the parms to go MAF only as you mentioned

1966 Nova SS 05212016 Dyno tune 3 MAF only.hpt (559.2 KB)
05242016 MAF only run1.hpl (1.15 MB) - No issues with this run, started and drove about 5 miles total with some full throttle cycles. Car wanted to die when coming to stop.
05242016 MAF only run2 with issue.hpl (1.00 MB) - Turned car off, looked at run1 log for 5 min, started again and had the issue...logged it for about 2.5 miles, turned off for a bit, started and issue was gone again. First half is the bad behavior and second half its working ok

Reloaded the original good tune and drove the 5 miles again with no issues
1966 Nova SS 05212016 Dyno tune 3 good pull.hpt (559.0 KB)
05242016 dyno run3 with no issue.hpl (1.02 MB)

This has me totally confused. I double checked the grounds on the system today and they checked out good...

[schpenxel]

I'll look through them in the morning--laptop screen is not very good for looking at several logs/tunes at the same time.

What's it doing, going lean basically?

[mufreq]

It is running really rough, going very lean, and absolutely no throttle response. If you slightly tip in, wait, tip in more, etc. you can get the RPM up under load to about 2000 RPM, but falls flat otherwise. It is really strange...also more strange is that it will clear up once you turn the motor off and start it again. gremlins I tell you! lol

[schpenxel]

What's the formula for the WB you're using? In the logs it's showing the MPVI input voltage but not lambda/AFR. I can make a math parameter to do it real quick if I know the formula. Even in the log that is labeled no issues it looks like it's going lean the first few pulls. About 6 minutes in there's a pull that AFR stays pretty steady.

I'd set the PE EQ ratio a bit richer and also change the other settings so it goes into PE easier/earlier. You were at 50% throttle and 5500 RPM's at one point and still not in PE. Mine always does weird stuff the first 10 mins or so after a flash.. not sure if that's what you're seeing or if it's just too lean to begin with, or maybe a combination of both.

[mufreq]

The NGK WB to convert voltage to AFR is V*1.4 + 9 according to the reference manual. also on the first set of files, I had it set up for MAF only and not allowing the system to go into VE. So these ECMs are that flaky naturally?

[schpenxel]

The NB O2's are showing it going lean too, even on the good runs

I wouldn't call them flaky. I would say after a flash they take 10-15 mins to settle down though. I usually get some lean spikes at first then they go away. I think yours is already borderline lean, then add in it just being flashed and it's lean enough to run like crap then.

That's just my best guess. It's hard to diagnose weird stuff like this over the internet looking at logs

[Z06-Hammer]

What MAP sensor are you using?

[mufreq]

I am running the 06 truck/trailblazer MAP sensor adapted to the LS3 MAP port.

[mufreq]

The NB O2's are showing it going lean too, even on the good runs

I wouldn't call them flaky. I would say after a flash they take 10-15 mins to settle down though. I usually get some lean spikes at first then they go away. I think yours is already borderline lean, then add in it just being flashed and it's lean enough to run like crap then.

That's just my best guess. It's hard to diagnose weird stuff like this over the internet looking at logs

Yeah I know its tough to figure something like this out via forum/logs. So would recommend richening up the VE table, flash, and then let it settle out over 10-15 min before trying to drive it again? I just got the car together so I am excited to get some seat time without being concerned that I may hurt the motor! :-)

[schpenxel]

Just for some nice round numbers I'd bump MAF/VE tables (whichever you're using, or both if both) by 5%, I would change the PE throttle table to something like 39% @ 0 RPM's, tapering down to 12% @ 2K RPM's then maybe 5% the rest of the way out, so it'll get into PE a lot quicker

I would also change the PE EQ ratio table to a little richer. It almost looks like what's in there now is the original truck table or something? It's pretty lean.

As a starting point maybe try 1.18 across the board, which is more or less 12.5:1. Not ideal to leave it just one flat number but it's a lot easier for the time being. Right now it's set for AFR of 13.6 then goes down to ~13:1 at 3K RPM's

(Based on a random earlier tune I opened--I haven't compared them all to see if any of this is already changed in any of them)

Give it 10 mins or so of driving around, maybe a romp or two, and then see how it does

[Area47]

did you flash the trans to a manual setup, or an auto setup? Does the tac model match the throttle body setup? i do not have hpt on my work computer, so I can not see for certain on the map itself, just shooting in the dark. Stability controls ae directly linked to the throttle body as the ecm uses it to control wheel spin and over all power when needed, so if the tac module does not line up with the tb, this would be an issue.

if you need a second set of eyes. im in KC as well.

[mufreq]

did you flash the trans to a manual setup, or an auto setup? Does the tac model match the throttle body setup? i do not have hpt on my work computer, so I can not see for certain on the map itself, just shooting in the dark. Stability controls ae directly linked to the throttle body as the ecm uses it to control wheel spin and over all power when needed, so if the tac module does not line up with the tb, this would be an issue.

if you need a second set of eyes. im in KC as well.

On the E40 setup there is not a TAC module. Yes I do have the trans set for manual mode as well. I appreciate the offer for assistance. I will tweak my tune like schpenxel recommended and give that a go to see how it works out. IF this continues to be a gremlin I'll ping you. Thanks!

[Area47]

not a problem man. what is the ls2 tb from btw?

[mufreq]

It is off an '06 GTO, silver blade type