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  1. #1

    Default high idle/ high engine compartment heat

    I have a 90 gmc 3500 4x4 454
    my problems are these : engine seems to idle to high warm or cold. at idle truck will acccelerate to over 30 mph on level ground,seems faster in reverse. have replaced air throttle control, new throttle body gasket.

    next problem:
    way to much heat in engine compartment,can cook on hood and fenders after even a short drive. has new cat and muffler dual exhaust. any ideas?

  2. #2


    Check where your cruise control cable goes in, if you have that. It might be cranked in, which would raise the idle way above normal.
    As for the heat issue, does your hood have insulation on the underside? Also, that could simply be caused by the first issue.

  3. #3


    i would be happy to do that if i knew where cruise cable was connected at.

  4. #4
    murdog94's Avatar
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    Feb 2008
    Cloquet, Minnesota, United States
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    Same bracket that your throttle itself connects on the Throttle body. Also have you taken a look to be sure the IAC servo was actually working when installed? Sometimes they will be bad brand new, and they can also be getting a poor signal and not work. And are the throttle blades closed all the way?


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