surging and stalling at idel

[mikemm212]

hello everyone. I've been working on my tune on and off for a few months. finally have my cartridge style maf in and calibrated and turned my ve stuff back on. It ran great the first day but after a few drives it developed surging and stalling when coming to a stop. it also has a slight hesitation when I first start accelerating from a stop. I have a afx wideband but is reads lower on the tunner than on the display so I don't really trust it.

5.3 with BTR stage 3 truck cam, 243 heads milled .20, tbss intake, 90mm Chinese throttle body, ebay cold air intake, long tube headers, 3600 fti stall

I have a short log of a cold start and then backing down the driveway it surges and dies.
advice is appreciated.

[cobaltssoverbooster]

Trust the gauge readout of the wideband. Transform your wideband channel to make the scanner match the gauge display.

[mikemm212]

Thanks for the input cobalt. I have fooled with it some and got it closer than when i started. Its about .3 lower most of the time. I do need to adjust it some more.

[mikemm212]

Also wanted to mention it doesn't surge much on my way to work when its 1pm and 93F outside. On the way home its close to 75F and it has alot more trouble staying running.

[KFXGUY]

it sounds like its learning itself bad. You need to limit how much your adaptive idle learns in the lower rpm cells. I had an issue like that. reflash it with no changes and work perfect for about 15-20 minutes of driving. if you log your LTIT and STIT (short and long term idle trim) you should have not much correction in either one. If you do and your running airflow is correct, then it is learning itself wrong. I assume you have a cam? the idle fluctuation from a cam will cause this.

[mikemm212]

I found a problem! I did not realize I needed to calibrate the intake air temp sensor table for the new maf. It was of about 20'F off. It had to relearn the fuel trims due to the temperature change between afternoon and evening. I found a table and copied it into mine and now have it about 4'F off which is probably close enough. Running much better now. I think I still need to go back over the VE table again. AFR jumps up when I first touch the gas.

KFXGUY ill keep that in mind if I have any more problems.
thank you for the input

[mikemm212]

The intake temp was not my problem it was running good for a couple of drives and has now returned to surging coming to a stop. I found a good write up on tuning base running air flow I'm about half way into it and I can see my numbers were way off. Also found its a good idea to make the high octane table match the idle spark table to prevent timing jumps from transitioning from one to the other. Once I'm done with airflow ill adjust timing and I bet that will be the end of it. Have my wide band reading fairly accurately now as well. Is 825rpm a good idle speed for my cam? 218/224 553/553 113+3

[KFXGUY]

The intake temp was not my problem it was running good for a couple of drives and has now returned to surging coming to a stop. I found a good write up on tuning base running air flow I'm about half way into it and I can see my numbers were way off. Also found its a good idea to make the high octane table match the idle spark table to prevent timing jumps from transitioning from one to the other. Once I'm done with airflow ill adjust timing and I bet that will be the end of it. Have my wide band reading fairly accurately now as well. Is 825rpm a good idle speed for my cam? 218/224 553/553 113+3

Personally I think that idle rpm is a little high. My cam in a 5.7 ifles at 725rpm. It’s a 227/234 113lobe separation. Yes get your idle air correct. Make sure your tps is returning to 0% when your coming to a stop. And tone down the idle air adaptives.

[mikemm212]

I set my idle to 725 warmed up in P/N and 750 in gear. I went through the RAF a couple of times, changed the idle speed, then went through one more time. I put my new numbers in my regular tune. Now when I start it its running about 11:1 AFR so the fuel trims go to about -15 to get it to about 14.7 afr even though I have stoich afr set to 14.3. any thoughts on why it does that?

KFXGUY if idle air adaptives cause that I'm not sure what I need to tone down or how much.

[KFXGUY]

I set my idle to 725 warmed up in P/N and 750 in gear. I went through the RAF a couple of times, changed the idle speed, then went through one more time. I put my new numbers in my regular tune. Now when I start it its running about 11:1 AFR so the fuel trims go to about -15 to get it to about 14.7 afr even though I have stoich afr set to 14.3. any thoughts on why it does that?

KFXGUY if idle air adaptives cause that I'm not sure what I need to tone down or how much.

The air adaptives should not cause that.

Thoughts.
Do you have your rear o2’s hooked up? On my ecm (2004 ls1 gto) I have to leave o2 or simulators plugged in because it goes through some even if I have them turned off. I just have the o2 plugged in and ziptied up. Fixed my issue.

What’s your commanded afr when that happens? You can add the channel and add it in the scanner

What about eq ratio. Have you messed with that?

Startup fueling? Messed with that?

I don’t have my laptop to look at your files right now.

[KFXGUY]

Also. Did you make damn sure your ve table is on point? How many hits in your scanner do you have it set to report an error at in the graph? I have mine set at 25

[mikemm212]

no rear O2's. no cats so didn't see a need for them. Guess I can add those to the scanner and see if they read anything. commanded is on there it's 14.27. If I messed with EQ I don't know where to find it again to check. I did try dropping cranking VE 10% it made no difference.

[mikemm212]

had it set to 50 hits per cell. It could be wrong since it was idling so bad but it is doing this in park not moving so it shouldn't be using the VE table right?

[mikemm212]

It's got to be something I didn't turn off in my RAF tune. The STFT slowly go down to -15 while I was logging RAF. Take a look at the tune and log when you get the chance

[kevin87turbot]

What PCM are you running? For some reason I can't view your cal file. Looking at the datalog, it has a lot of ignition timing at an idle...way too much.

[mikemm212]

What PCM are you running? For some reason I can't view your cal file. Looking at the datalog, it has a lot of ignition timing at an idle...way too much.

Thank you for looking at that for me. Its a 0411 PCM. The highest value on the idle spark table is 33. not sure why it is going up to 40. Ill drop it to 23 across the board and see if that helps.

[240sxpooter]

Thank you for looking at that for me. Its a 0411 PCM. The highest value on the idle spark table is 33. not sure why it is going up to 40. Ill drop it to 23 across the board and see if that helps.

Tried to look over your tune and Hptuners says that the file is part of a tuning network I am not apart of...weird

Are you tuning MAF , Map or both?

Have you tried opening your throttle plate mechanically? That's probably where I would start with a little more mechanical airflow. As your iac steps are a little high.

You can always reduced the idle timing ramps (overspeed, underspeed) a little to help with the timing swing.

I had some major issues with my cam on a maf tune. Set it up in SD and it helped a lot.