2002 LM7 Stalling Issues

[twenglish1]

LM7 engine with BTR truck norris cam, NNBS intake manifold, 92mm throttle body with the typical small IAC passage, Long tube headers, 4l60E with 2500 - 2800rpm torque converter. Still need to dial in the higher end of the VE table and have alot of smoothing to do. Lambda readings are all close to 1 in the everyday driving areas of table. Decided to spend some time getting the idle set up, up until this point i had my BRAF table zeroed out, and idle air was set with the throttle stop screw. I put the stock values back into the BRAF table and set up the scanner to log STIT against ECT, started it up and idled it for an entire warmup cycle. Added the STIT values to the BRAF table and smoothed the extreme ends. After running a second full warmup cycle and adding the STITs to the BRAF table a second time, while idling STITs are very lose to zero, and i was able to back off the throttle stop, IAC counts down to about 70. Repeated the same with the in gear BRAF table. Following some other posts around the internet, increased the idle spark advance, made adjustments to over/underspeed error, and increased idle speed. I have definitely made huge improvements, rpm drops to about 500 when coming to a stop in drive, rarely stalls now though, reverse is a different story though, when hitting gas to back up, engine almost always stalls when coming to a stop in reverse.
Current tune file attached and initial idle log
Current Tune - Idle Tuning.hpt
Idle Warmup.hpl

Let me know if i am missing any data points, still new at this, but i feel like i am making progress

[SiriusC1024]

Re-enable CL.

[tana99ss]

Few things here, i think you need to learn a bit more about tuning. I say that because your VE is all over the place (literally) Which possibly means you are making the adjustments in the wrong table. .

what i would do if i were you, i would Put everything back stock, then slowly adjust the proper tables correctly.
Easiest is MAF Table. Force it into MAF Only Mode, turn your SFTF. LTFT back on. and slowly make the adjustments there.
once that is dialed in Change it to VE only and disable MAF.

once you have done that you should have a small idea where you need to be on tables. At this point i would drive it a bit get it dialed in some more ( low rpm ~2500 or so) update the maf and ve tables.

One you have adjusted a little bit of those table you should be able to find the correct BRAF points to get you rolling.

[twenglish1]

Currently have MAF disabled, it is not calibrated yet anyway, AEM wideband wired to EGR position input, pretty sure I have the math right on that, will post my formula later, converting the voltage to lambda per AEM manual and comparing it against commanded lambda converting to percentage and plotting it against RPM and MAP to create the VE with lambda error percentage, then using multiply half percentage over VE calibration table. I will start over using the fuel trims if you think this is the better option, everything I had been seeing up until this point was to use a wideband for everything

[SiriusC1024]

Yep use CL trims. Should just need a little fine-tuning, so not really starting over.
https://forum.hptuners.com/showthrea...l=1#post760887

[twenglish1]

Spent some time on the car after work today, decided to start fresh with a factory VE, set up the short term and long term fuel trims, it was a little rough for the first couple logs/short trips but after about 5 logs, and maybe a total of an hour and a half of driving, wow what a difference, it is running significantly better than it was with the lambda error calibrated VE table. VE table is still getting a little spiky, is this normal? how should it be smoothed out? I have been copying the logged VE table and paste special multiply half percentage, just wanted to confirm that this is the correct method of applying the trims to the VE table? I am still having issues with stalling in reverse, have to really give it some gas because of the higher torque converter stall speed, so when hitting gas and releasing it quickly rpms drop below 500 and it usually stalls. This happens sometimes in drive as well, when hitting gas and then brake quickly. Attached is the last log and the most recent calibration that was adjusted from the same log. Wasn't a very long log but i think things are looking alot better.

Fuel Trim Tuning.hpt
5.hpl

[tana99ss]

my concern with the tune is bank 1 shows 20% LTFT during some of the idle while bank2 never really logs more than 2% LTFT.

i would assume an injector leak or maybe clogged on the other side. maybe someone can provide a bit more input on that.

[SiriusC1024]

my concern with the tune is bank 1 shows 20% LTFT during some of the idle while bank2 never really logs more than 2% LTFT.

i would assume an injector leak or maybe clogged on the other side. maybe someone can provide a bit more input on that.

Yep. Should log B1S1 and B2S1 O2 voltages.

[twenglish1]

So this might be the issue that i should have mentioned sooner, i am currently running one o2 sensor on passenger side bank, wideband is installed on driver side header, I have the narrowband wired to both upstream o2 inputs as per this article I found on Lowbuck LS, however looks like I missed the part it mentions of zeroing out the "injector bank select table" this should make it fuel both sides equally off the one sensor? I understand it would be better to utilize both o2 sensors as originally intended.

https://lowbuckls.com/closed-loop-wi...the-stock-ecm/

[SiriusC1024]

That's for turbo where both banks merge into one pipe. It's not ideal. Normally both narrowbands are left in then a wideband is installed in another spot.

[twenglish1]

Forced induction might be a possibility in the future, I'm not sure yet, I made the wiring changes on the sensor side of the connector so it would be easy to revert back to factory, I think I will change those settings for the time being and try it as single bank operation, ill still have the wideband readout incase something goes wrong on that bank. I think this explains why my wideband seemed to be showing opposite of the fuel trims, fuel trims were adding fuel and the wideband was showing it was already rich, from pcm making changes to the unmonitored side fuel trims, and wasn't seeing the changes reflected in o2 readings?

[SiriusC1024]

As long as there isn't something causing a huge imbalance it'll be ok.

[twenglish1]

Can I use the short term and long term idle trims to get the IAC set up properly just like the fuel trims? And what are we looking for in fuel trims? Less than 5% adjustment?

[SiriusC1024]

Yes and yes

[twenglish1]

Getting much better! Added some extra idle air and it seems to have solved the stalling issue. Every now and then i'm getting some minor hesitation in spots, but i think that should work itself out, log number 11 and current tune attached, did some manual smoothing on the VE just adjusting the sharp points down or up to near the cells around them, i guess next would be interpolating out to the edges, and between areas i can't seem to hit? I still need to hit the high RPM cells, but i need to avoid hitting power enrichment for tuning using the fuel trims? I haven't touched any of the PE settings yet.

11.hpl
Fuel Trim Tuning - Smooth.hpt

EDIT: Just so i am getting this right, currently setting up the charts for idle trims, LTIT PN AC Off + Idle Adapt STIT for park neutral, and LTIT Gear AC Off + Idle Adapt (STIT). Then these logged values are added to their respective Base Running Airflow table?

[SiriusC1024]

Which injectors are you running? Got a part number off them?

[tana99ss]

Getting much better! Added some extra idle air and it seems to have solved the stalling issue. Every now and then i'm getting some minor hesitation in spots, but i think that should work itself out, log number 11 and current tune attached, did some manual smoothing on the VE just adjusting the sharp points down or up to near the cells around them, i guess next would be interpolating out to the edges, and between areas i can't seem to hit? I still need to hit the high RPM cells, but i need to avoid hitting power enrichment for tuning using the fuel trims? I haven't touched any of the PE settings yet.

11.hpl
Fuel Trim Tuning - Smooth.hpt

EDIT: Just so i am getting this right, currently setting up the charts for idle trims, LTIT PN AC Off + Idle Adapt STIT for park neutral, and LTIT Gear AC Off + Idle Adapt (STIT). Then these logged values are added to their respective Base Running Airflow table?

im still seeing the 25% ltft this time in bank 2.

Just to make sure, i would double check your o2 sensor connectors, make sure your b1s1 sensor isnt plugged into the b2s1 location. sounds silly but its happened before and should be a quick check.

[tana99ss]

also can you add fuel system status on your log please

[twenglish1]

Need to disregard long term bank 2 i think, set up now for single bank fueling as talked about above, i do however need to correct my logger setup because the trims on bank 2 will be throwing it all off? Not sure why it is still changing though? If this will be an issue i will add the other narrowband back, will add loop status to scanner as well. Current fuel injectors are Denso 25326903, i cannot confirm where i got my 38.6 flow rate, tried searching again and there is alot of conflicting information on these injectors. I previously had a chinese aftermarket set but got rid of then due to suspected inconsistencies, I also have a set of 12594512 injectors as well i could swap in if they are a better option. I understand that the injectors are extremely critical in getting all this correct.

[twenglish1]

Forgot to add, return less fuel rails, using the corvette filter/regulator, and can confirm 58psi at fuel rails at idle, haven't checked under load