IAC position vs airflow discussion
IAC position vs airflow discussion With the release of hptuners 1.6 there's a new table that wasn't available for editing before, the IAC position vs effective area table. I think this could be useful for getting desired IAC position to match actual IAC position.
I think a problem people run into is when they drill their throttle body or adjust their set screw, the tb has more effective area than the pcm knows about which means the pcm will think it has to open the IAC more than it has to to get the same airflow. If you look at the IAC position vs effective area table, it is 0 up through 12 (which is in mm^2 if i remember right). Which leads me to believe the stock tb hole has an area of about 12 mm^2. If you drill the tb or adjust the set screw, you're increasing the area to more than 12 mm^2 so you should adjust the table to match. That could be done by simply shifting the table to the right.
I haven't tried this yet so i'm curious if there's anybody who has (AnotherUser?). I do have a question for the hptuners guys though. Does the IAC effective area to airflow conversion depend on the vacuum across the throttlebody (baro-map) in the OS code?
I think a problem people run into is when they drill their throttle body or adjust their set screw, the tb has more effective area than the pcm knows about which means the pcm will think it has to open the IAC more than it has to to get the same airflow. If you look at the IAC position vs effective area table, it is 0 up through 12 (which is in mm^2 if i remember right). Which leads me to believe the stock tb hole has an area of about 12 mm^2. If you drill the tb or adjust the set screw, you're increasing the area to more than 12 mm^2 so you should adjust the table to match. That could be done by simply shifting the table to the right.
I haven't tried this yet so i'm curious if there's anybody who has (AnotherUser?). I do have a question for the hptuners guys though. Does the IAC effective area to airflow conversion depend on the vacuum across the throttlebody (baro-map) in the OS code?
Might this be a reason why I have IAC position values of 140-160 at idle with no load? I raised the set screw to 4% TPS and then zeroed it. I cant figure out why my IAC position values are so high!
