Idle dip w/M6 cammed LS1 F-body

[DrkPhx]

Hi,

I will post a log later, but I wanted to see if anyone could help.

I'm tuning a friends 00 TA with a small cam (232/236 .595 113 lsa) and FAST 90mm (the TB is NOT drilled) and I need some help. It's a M6 car. It idles really nice (except with the AC on) at 800 rpms with no problem. However, there is an odd problem that happens on deceleration I can't eliminate completely. When the clutch is engaged and released the idle will dip to 450-650 rpms for a second then come back up. I lowered the idle speed to 775 rpms which made it less noticeable, but it's still there and seems to get more pronounced as the car and ECT warms up.

I've disabled the Throttle Cracker to eliminate the hanging idle, but the problem was still there when it was active. Adding idle airflow and spark will make it worse. The spark values match in all timing tables to prevent any fluctuations. Fuel trims are ok. I haven't put a WB on it yet, but will later this week.


Any help or input is appreciated.

[SSpdDmon]

Don't disable throttle cracker. Use it wisely. You can add in airflow to the first row of the throttle cracker to help prevent the dip and remove airflow where you have a hang up. You can also add in timing in the area of the issue....just make sure you add it to the right map (high/low or base timing based on B5916 & B5917). Keep in mind if you add timing to the timing maps, the idle underspeed error table (engine cal>spark>idle folder) may need to be softened up some.

[DrkPhx]

Don't disable throttle cracker. Use it wisely. You can add in airflow to the first row of the throttle cracker to help prevent the dip and remove airflow where you have a hang up. You can also add in timing in the area of the issue....just make sure you add it to the right map (high/low or base timing based on B5916 & B5917). Keep in mind if you add timing to the timing maps, the idle underspeed error table (engine cal>spark>idle folder) may need to be softened up some.

Thanks for the information. I will give that a shot and see how it works.