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Wade wrote: ↑Mon Mar 10, 2025 7:13 am The way i look at it. Iac spark correction lower coolant threshold is the minimum temp idle spark correction can be made. So from -40 deg/c on up. There is also another scaler for the vy v6 min coolant for learning airflow which is set around 87 deg/c. So pretty much only learns airflow pretty much at operating temp. But if you’ve changed to a colder thermostat you might not even reach that temp especially if you’ve lowered thermo fan activation temps as well. Then you’ve got rpm error limit for spark correction and the idle spark correction limit. Not sure if the rpm error limit is a max or min? Probably max if it’s 512rpm. Idle spark correction limit is obviously the maximum amount spark can be advanced or retarded to achieve the desired idle rpm. Then obviously you’ve got high and low rpm correction multipliers. It’s like 0.04 % of a deg per rpm or something like that. Think it’s 0.03 for the manual ?. So if you log actual idle speed vs commanded and if actual idle speed is over what it’s supposed to be then it’ll remove ignition timing. That’s where iac airflow comes in. The closer you get iac g/s to where it should be, the less ignition timing needs to be advanced or retarded to achieve the desired idle rpm. I know with the vy eco spark cranking is /256*90-20 and gives around 15deg at cranking. You can log this. Before starting the car remove fuel pump fuse or relay and ignition on start logging. Log while cranking and see what ignition timing is reading. If it doesn’t match then change the last -20 to something else until it’s matches what your logging.

Wade wrote: ↑Mon Mar 10, 2025 7:13 am The way i look at it. Iac spark correction lower coolant threshold is the minimum temp idle spark correction can be made. So from -40 deg/c on up. There is also another scaler for the vy v6 min coolant for learning airflow which is set around 87 deg/c. So pretty much only learns airflow pretty much at operating temp. But if you’ve changed to a colder thermostat you might not even reach that temp especially if you’ve lowered thermo fan activation temps as well. Then you’ve got rpm error limit for spark correction and the idle spark correction limit. Not sure if the rpm error limit is a max or min? Probably max if it’s 512rpm. Idle spark correction limit is obviously the maximum amount spark can be advanced or retarded to achieve the desired idle rpm. Then obviously you’ve got high and low rpm correction multipliers. It’s like 0.04 % of a deg per rpm or something like that. Think it’s 0.03 for the manual ?. So if you log actual idle speed vs commanded and if actual idle speed is over what it’s supposed to be then it’ll remove ignition timing. That’s where iac airflow comes in. The closer you get iac g/s to where it should be, the less ignition timing needs to be advanced or retarded to achieve the desired idle rpm. I know with the vy eco spark cranking is /256*90-20 and gives around 15deg at cranking. You can log this. Before starting the car remove fuel pump fuse or relay and ignition on start logging. Log while cranking and see what ignition timing is reading. If it doesn’t match then change the last -20 to something else until it’s matches what your logging.