Idle surge

[BOTTLE FED]

I am looking at 02 rich/lean vs airflow (is this what you are referring to?) I compared to a stock tune on the repository and they are identical to mine
BTW - it does have headers, no cats and ti's

I changed the open loop, 50* - 122* to 13.8

[BOTTLE FED]

Does anyone have a stock 98-99 C5 tune they can post. I don't have one and for some reason Im not able to download one from the repository. I need to see the stock Idle airflow table.

[MMGT1]

Attachment 41645

[BOTTLE FED]

Here's my latest update;
I copied the stock idle airflow table and added 4g to the chart - car would not stay running
I then changed the scaler to .0191 and tried - car would not stay running
I put scaler back and added 2g more to the idle airflow chart - car would not idle
I went back to my earlier tune (with the high idle airflow table and added 1g to the cooler parts of the table - car idles but Fluctuates up and down (400rpm) every time you go from part to gear or back
Thanks for you guys patience and help

[MMGT1]

What will it do if you clear out the over/under timing for idle?
When you said it got worse if anything when you unplugged the MAF, did you try adjusting Commanded AFR/timing at the time to try and find it with live controls?

[JnJSpdShop]

Well 26° of idle timing is likely too much. GM OS uses throttle opening and timing to control engine RPM. Timing is the fastest way to control but when you are at make torque output more timing will not pick up engine RPM any. Your Base Running Airflow is very high and likely not correct. Why did you chop down the over speed and underspeed timing table? Doing that you are just handicapping PCM ability to control engine RPM through adding or subtracting timing. Your PE isn't correct and you are using larger injectors with stock injector characteristics.

[BOTTLE FED]

Thanks guys, will try to try some more today.
I've since dropped the timing back to 24*
I'm also reading everything I can get my hands on, and per the "tuning school" manual (which I attented a few years ago) when you are having idle issue with a much larger than stock cam, the over/under just makes it worse, so I dropped it to the recommended 2/-2
I also used the provided instructions to scale the new injectors when I installed them, so I'm not sure why they are off.
The PE table "commands" low, but at least the end result is the one of the few things that is dead on, which is the AFR at WOT which is a perfect 12.9 through the range.
The car actually ran pretty much perfect before I upgraded to the FAST 92/LS2 and LS6 MAF. If I hadn't sold the intake I would try swapping back temporarly. I have sprayed to see if I have leaks that may cause the issues, but cant find any.

[MMGT1]

I wanted to know the result of 0 in the over under because I am thinking he needs more than usual in that table. If 0 doesn't make it go buck stupid then its back to that throttle body. Idle timing at 24* in park neutral may be what it needs, it may also need up to 30* timing in Drive idle, but need to go the steps before just throwing it at it

[BOTTLE FED]

I tried zero in the O/U table and it MIGHT have been a little worst. I tried easing it back to 4/-4 and it seemed actually a little better
I tried the manual controls in the scanner, and more timing did not help at all but when I lowered it, it was worst.
I have been trying to play with the idle airflow table, since it seems to be the only thing affecting it, but I STILL can't get it all out
Once it settles in after cranking, it will idle pretty well. It fluctuates between 720-920, which is not bad. HOWEVER, when I move from park to gear, or back, it drops by 400 rpm and almost stalls. But worst, if you slowly rev it up in neutral and let off the gas, it drops below 500 and occasionally dies.

[JnJSpdShop]

Make sure you air/fuel is correct first. Next work on your base running airflow and idle timing. Start at 20 degrees and work with the idle tables