ComancheKid45 Posted January 3, 2009 Share Posted January 3, 2009 Hey guys, the last few times i started up my truck it wants to rev really high for minutes on end.....Would this be a sign of a bad IAC? I don't have a tach so i can't give ya an accurate RPM measurment, sorry 88 4.0 AW4 Thanks for any info Link to comment Share on other sites More sharing options...
jvwilliams Posted January 3, 2009 Share Posted January 3, 2009 I have having this problem intermittantly ever since I bought the 87 Commanche, 2-1/2 years ago. It was rare, but now it is becoming more frequent. It only happens on a cold start but it revs to 2500 - 3000 rpm. Today I cleaned the throttle body (in place). The IAC was cruddy. I finally replaced it ($114 at NAPA) but upon restart it went to 3k again. I loosened the TPS and moved it to the stops. Pushed all the way down, the idle dropped to 1000 rpm. Tomorrow I am going to reset the ECM and see what that does. I know this don't help you, but I just wanted you to know that you are no alone. This came on the heels of the left rear axle seal going out. After I replaced it and the bearing, I cranked it up for a victory run, and it done this crap. Link to comment Share on other sites More sharing options...
BLHTAZ Posted January 3, 2009 Share Posted January 3, 2009 Hey guys, the last few times i started up my truck it wants to rev really high for minutes on end.....Would this be a sign of a bad IAC? I don't have a tach so i can't give ya an accurate RPM measurment, sorry 88 4.0 AW4 Thanks for any info It is possible that the IAC is bad, but it's also very likely that you just need to clean it and the throttle body too. Try a good cleaning first. Tomorrow I am going to reset the ECM and see what that does.You don't have an "ECM". It is an "ECU" and there is no way to "reset" it as it resets itself every time you shut the truck off. An ECU is simply an Electronic Control Unit that operates on a fresh boot every time it's started and controls the truck off of preset perameters that cannot be "reset". It does not store codes or faults that can be cleared :smart: :cheers: Link to comment Share on other sites More sharing options...
ComancheKid45 Posted January 4, 2009 Author Share Posted January 4, 2009 A Nice cleanup seems to have fixed the problem :thumbsup: Link to comment Share on other sites More sharing options...
BLHTAZ Posted January 4, 2009 Share Posted January 4, 2009 A Nice cleanup seems to have fixed the problem :thumbsup:Good deal...usually does :cheers: Link to comment Share on other sites More sharing options...
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