foreverford72

I have a 95 with a 5.8 that is starting to give me headaches. Recently purchased it with a constant high idle. The IAC appears to have been replaced fairly recently. EGR is working properly. No vacuum leaks. I replaced the TPS, reset computer. On start up it idled high for all of 2 minutes if not more, then dropped to normal. Test drove about 10 miles, ran and shifted perfect. After sitting overnight on start up had high idle again and didn't drop down. Checked codes again, ECT out of range. Replaced ECT sensor. Back to high idle at start up but does drop down after approximately 2 minutes or so. It does this on cold starts and on normal operating temp starts. What am I missing? Is it possible the IAC is bad? I've read in other threads that it should die if the IAC is unplugged, if that's correct, mine doesn't die. Thanks for any help.

Crownman

When you say high idle what RPM is it?

foreverford72

It was running around 1200 to 1500 rpms. Went with my gut instinct and changed out the IAC. Problem solved. Thanks

fltdriver

FFR unplugging the IAC doesn't kill the truck, the test is to unplug the IAC then start the truck, if it idles better when started w/o IAC then IAC has high chance of being the problem, real test is to ohm test (7-13ohm is functioning properly, anything else and the solenoid is shot). Glad you were able to fix the problem.