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

Discussion in 'Chevy Truck Forum' started by chevyguy, Dec 12, 2009.

  1. chevyguy

    chevyguy Senior Member

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    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.
     
  2. bubbatrucklover

    bubbatrucklover Senior Member

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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.
     
  3. 436'd skylark

    436'd skylark Senior Member

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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.
     
  4. mudseeker

    mudseeker Senior Member

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    throttle body gasket, those are notorious for it.
     
  5. stumpuller454

    stumpuller454 Well-Known Member

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    +10000000%
     
  6. crabtruck

    crabtruck Senior Member

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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. bradrhale

    bradrhale Senior Member

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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. silverhairdeere

    silverhairdeere Senior Member

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    glad to see you up and with a clear mind so early today , i'am proud of you son , keep up the good work
     
  9. bradrhale

    bradrhale Senior Member

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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. 79jimmy

    79jimmy Full Member

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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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