IAC vs Effective area

[yukio]

I am in the process of tuning my LS6 and having minor trouble with idle and think that IAC vs effective area might be the problem.

There is three different scenarios which will describe my idle issues.

1. If i start the car cold, it will start and IDLE fine. If i drive rev it, it will come right back to idle(around 900rpm), and stay there steady. As long as the engine temp is cold, and the idle IAC value remains the same.

2. If i start the car cold, it will start and IDLE fine. However if i drive around from a cold engine and then get the engine hot without restarting the engine/ecu it will have problems holding idle. It will drop low and most of the time stop.

3. If i start the car hot, it will start and IDLE fine. If i drive rev it, it will come right back to idle(around 850rpm), and stay there steady. As long as the engine temp is steady, and the idle IAC value remains the same.

I have changed many paremeters in both IDLE Airflow and IDLE RPM, but not the IAC vs Effective area.
When calculating the RAF/Base idle airflow table, as i understand it. It will to hold a certain RPM by setting the BASE running airflow, then adding STIT and LTIT wich will correlate to a certain IAC value. Then the ECU will go into the IAC vs effective area to figure out how many square millimeters of air that is, and then calculate how much air that is(g/sec). Using russ k IDLE.cfg will give you an good estimate of a new Base running airflow. However if that IAC vs Effective area is wrong wont the whole base running airflow also be wrong?

I did log IAC, Desired airflow and dynamic airflow. At lower IAC count they where overlapping, however on higher IAC counts(150+, cold engine) they did not. Desired airflow was much higher than dynamic

Can this be my problem, since the BASE IDLE AIRFLOW table will try to set the correct airflow with IAC count that does not correlate with the correct amount of air(g/sec)?

How do i adjust the IAC vs Effective area?


MODS
LS6
AFR 210 Heads
Fast 102 intake
102mm TB
Drive by cable
SD

Idle-Airflow.cfg250514_idle2.hpl250514_IDLE.hpt


Thanks
Tommy

[RonSSnova]

I noted that you have the adaptive idle stuff zeroed out for the most part.
I was reading on the subject just last week and Russ K says his idle config needs that all turned on.
Just a thought.
Your RAF has a big step that doesn't look normal at all