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  1. #1
    Senior Member
    Join Date : Sep 2005
    Location : ALABAMA
    Posts : 4,053
    Likes: 3

    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.
    The only good thing that came from cash for clunkers is that it got most of the OBAMA bumper stickers off the streets.

  2. #2
    Senior Member
    Join Date : Jul 2009
    Location : Jacksonville, Florida
    Posts : 952
    Likes: 0
    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.
    Siggy by Crimson Dragon >>>>>>>>>>>>>>>

    _____________________________________________TRUCK MOD DONATIONS ACCEPTED

  3. #3
    Senior Member
    Join Date : Mar 2007
    Location : Pennsyltucky
    Posts : 1,142
    Likes: 0
    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
    1962 Scout 80 parts I guess
    1966 Scout 800 resto job
    2005 Chevy 2500HD Short cab long box DURAMAX
    1996 P30, 6.5 NA Mac Mobile
    whole lot of buicks

  4. #4
    Senior Moderator
    Join Date : Feb 2006
    Location : michigan
    Posts : 8,537
    Likes: 14
    throttle body gasket, those are notorious for it.
    <----just your average 5.3

  5. #5
    Senior Member
    Join Date : Dec 2007
    Posts : 2,206
    Likes: 0
    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.

    +10000000%
    Gone.

  6. #6
    Senior Member
    Join Date : Jul 2007
    Posts : 5,566
    Likes: 12
    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
    Senior Moderator
    Join Date : Apr 2006
    Location : Texas
    Posts : 11,158
    Likes: 14
    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
    Join Date : Feb 2008
    Location : land between the lakes tn
    Posts : 1,831
    Likes: 0
    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
    Senior Moderator
    Join Date : Apr 2006
    Location : Texas
    Posts : 11,158
    Likes: 14
    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
    Full Member
    Join Date : Nov 2009
    Location : abbotsford canada
    Posts : 16
    Likes: 0
    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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