This may have been discussed many times before but my search wasn't resulting a clear answer:
Is GMPP crate engine E67 ecm different from cars from production line?
I have been struggling with 2 separate E67 controls and both seem to have some weird things especially in idle air control. It seems no matter what I put into airflow final minimum or idle speed, it idles the same. Today I studied one LS3 in C2 Corvette in which the cam has been replaced lately and it was idling with almost zero ignition advance to keep it at desired idle while the t/b was 20% open. I was aiming to get the t/b opening smaller and ignition advance up but no matter what I did, the blade was 20% and the ignition advance so low that when you start driving, the advance jumps ~30 degrees up and causes jerky movements. I put very small advance in main table on idle area and a bit on top of that to get the car moving more softly but I think this is the wrong way to tackle the problem.