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IAC Adjustment

With car in Park, engine fully warm, A/C off, look at the IAC counts on the scan tool.  If you wish to lower the count number, turn the adjustment screw clockwise. To increase the counts,  turn it counterclockwise.  Turn the screw a small increment, turn the engine off, and restart.  This insures that the IAC resets and confirms the adjusted number.  Continue until the desired number is achieved.  Often, on stock set ups, about 1-1 1/2 threads of the adjustment screw will emerge thru on the lever side of the throttle body.  Restarting also re-zeros the tps as stated in the prior section and removes any effect on idle speed that may have occurred due to tps movement.  The IAC counts will probably be 30 counts, or more, higher on a cold engine than on a warmed up engine.  The counts will also be much higher in gear as compared to Park, and, higher with the AC turned on. 

Adjusting the IAC screw will change the TPS idle setting so recheck that when you finish with the IAC.

Go to the Basics section and read the complete write up on the Idle Air Control for a more complete understanding as to the workings of the IAC solenoid.