On your supercharged car what does your IAC read at idle once the car warms up? I was wondering if it is high because of the blower. Mine reads 53.

 

I saw 110 the other day here in vegas, with the blower off the car! I'm wondering if I'm reading a little high?

 

I just moved my MAF from behind the air filter to the pressure side just in front of the throttle body. My throttle response time improved tremendously, but it created a new bug. P0123 (Throttle/Pedal Position Sensor/Switch A Circuit High Input ). Also, my idle has risen slightly. My IACs use to be around 65, now they're above 110.

 

Mine stay around 59 or 60

 

Does the hot temperatures have anything to do with the IAC reading? I'm in Phoenix (Burning hole from Hell) and JWS6 is in Las Vegas.

 

I got my highest reading on the hottest day so maybe.

 

The IAC reading is a good indication of how well your car is idleing and how much load is on the car. When the AC compressor kicks on the IAC will usually increase by about 15 to support the load. A blower car will naturally be a little higher than normally aspirated because of the load from the blower. Mine is at 60 and when the AC turns on it goes to 75. As long as it is not maxed out at 120 or minned out at 0 your OK. If it becomes max/minned out you can adjust the throttle screw about 1/4 turn and bring it back within range.

Some people keep their IAC's high to help with cam surge. The air through the IAC goes to ports directly in the intake runner which helps with a complete charge when the rpms's are low and vacuum is high.

If you have access to tuning software; Find out what IAC your car likes immediately after start(when cold) and put it in the box for "initial IAC at Startup" and it will make your car start better. However after that the car will make its own secret target IAC that you can't change. If you ever notice your car will tend not run that good immediately after tuning. That is the IAC and AFR trying to find a new sweet spot. It clears up after about 2 drives.

The IAC is also a good indicater of vacuum leaks and other problems and can be used to find out what timing your car likes at idle. Our cars use timing and IAC to adjust our idle speed automatically for all conditions. GM really did us a favor with such a good system.

BTW: If you live in Phoenix or Las Vegas you need to move out of the desert. High temperature and Density Altitude will definitely increase your IAC count.