1999 Isuzu Trooper, high idle

I have a 1999 Isuzu Trooper with a very high idle (3000rpm in Park) that started after I plugged in the Idle Air Control valve (found it unplugged). I reset the IAC via my manual’s instructions with no help. I also cleaned the IAC and the port where is goes into the throttle body and that didn’t help. I don’t want to replace the IAC and find out that something else was wrong. Any suggestions?

It sounds like the idle air control valve (iac) is full open. Did you set the iac pintle (the part that moves) to the position the manual says to? If you didn’t get the instruction, go to an auto parts store and ask to look at the instructions on an iac valve. Also, the iac valve may not be getting a signal, or power, it should. You need a digital voltmeter, or a scan tool, to check for those voltages.

Thanks for all the help. Yes I did set it to the correct position (less than 28mm) to no avail. When I took the pintle off I connected the electrical cable and run the reset procedure and the pintle reset. The inside of the throttle body where the pintle moves is clear of carbon deposits so I think it’s moving freely. I think it may be time to bite the bullet and take it into a mechanic to run a diagnostic. If you have any other ideas though I would be appreciative. Thanks again.

HAve you taken it to AutoZone (or a similar store) for a free scan for diagnostic trouble codes?

I live in a small town in Alaska and we don’t have an Auto Zone. I did try taking it to Schucks and they said that since my “Check Engine” light was not on a computer scan would not help. I took the Throttle Position Sensor off and cleaned it as well with no change in results.