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Thread: Need to prove a point. TBI Chevy high idle question.

  1. #1
    Senior Member chevyguy's Avatar
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    Need to prove a point. TBI Chevy high idle question.

    93 Chevy TBI 5.7 has a high idle on start up. Runs at about 1500 RPMs till it warms up then drops to around 1000-1100 Its my brothers truck and I am trying to help him with it, but he wont listen to me for some stupid reason. Anyhow I cant tell you what I told him I think it is. but what syas the Truck forum Chevy gurus. Help a brother out. ( Wow cant believe I said that) Oh well I already hit post so it stays.
    Window tint its for window, Not for tail lights. Don't be that guy .

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    Senior Member bubbatrucklover's Avatar
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    Worn TBI to intake gasket? I had a simular prob in a van where the gasket got so bad it wouldn't expand enough after warming up and had to get replaced.

    I will edit to add pcv and or the grommet surrounding it.
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  3. #3
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    Its a either a vacuum leak, or the IAC isn't seating properly. Thats assuming the throttle plates are shutting. of course if the coolant temp sensor was reading low, it would idle high. it would also run rich, which you didn't mention.
    Joe
    89 K2500 Chevy, Wee-Oh-five 294K miles
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    whole lot of buicks

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    throttle body gasket, those are notorious for it.
    <----just your average 5.3

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    Quote Originally Posted by 436'd skylark View Post
    its a either a vacuum leak, or the iac isn't seating properly. Thats assuming the throttle plates are shutting. Of course if the coolant temp sensor was reading low, it would idle high. It would also run rich, which you didn't mention.

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  6. #6
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    I'd also venture that it just plain idles high, not just at start up.
    Seems warm idle is about 300 or so high as well.

  7. #7
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    vac leak seems to be the general consensus here. ill raise you a TPS. (i thought id just throw that in there since no one else did.)

  8. #8
    Senior Member silverhairdeere's Avatar
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    Quote Originally Posted by bradrhale View Post
    vac leak seems to be the general consensus here. ill raise you a TPS. (i thought id just throw that in there since no one else did.)
    glad to see you up and with a clear mind so early today , i'am proud of you son , keep up the good work
    SHD

    1989 GMC 1500 (PROJECT CHEAP TRUCK)

  9. #9
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    think i am over my sickness and got good sleep last night. with as slick as im feeling right now, everyone needs to watch out.
    just trying to figure this brother thing out. i know CG knows about chevys. am sure his family knows the same thing i do. perhaps someone is being bullheaded.

  10. #10
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    you can find a vacuum leak by using a small propane bottle turned on low and pass it around and over your intake, if the rpms increase theres your leak. friend of mines dad was a mechanic and taught me this trick, works great for any motor.

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