ZL1 hanging idle/general idle issues

Hello everyone,

I know there has been a lot of posts regarding hanging idle issues, but I cannot find anything which has really helped me nail down the problem my customer is having with his idle hanging at 1500 rpms for a few seconds when going from driving at part throttle or full throttle and transitioning to neutral, such as going to a stop sign. I am picking this tune up after someone else who could not get his driveability dialed in, so please bare with me.

Additionally, I have tried to shy away from the "add or subtract timing at idle" method to control large cams such as my customer's, and use the integral and proportional tables to increase idle quality. This method of increasing proportional and decreasing integral has been counterintuitive in this vehicle. The idle only gets worse and oscilates when it should get better according to logic. Therefore, I have to revert back to the add and subtract timing method combined with additional base idle airflow. This is why I think the idle may be hanging when he comes to a stop, but I cannot be sure. Please help in whatever way you can. Sorry, I cannot attach a datalog since my computer decided to crash on me this week.

Thanks,
Alex Attachment 41601

by the way,

this car has about the largest cam which is available for LSAs. Not sure on exact specs, but its a pretty nasty overlap, which may explain why the base idle airflow is so high on this tune which I picked up from the last guy. I just don't like to do idle tunes this way. I like to control them with proportional and integral tables.

May want to repost this in the GEN 4 section (which your powertrain still is). Probably get a little more help there.