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Thread: high idle

  1. #1
    Newbie
    Join Date
    Feb 2010
    Location
    Soest The Netherlands
    Posts
    8

    Default high idle

    hi guys,
    i'm the owner of a Suburban with a 454QI TBI engine.
    the problem is that when i'm slowing down to stop from speed, the engine stays on high idle.
    when i go to nutral the engine go's to normal idle.
    excuse my english. i'm from holland, europe.
    Last edited by jeroen; 02-05-2010 at 04:37 PM.

  2. #2
    Sr. Apprentice
    Join Date
    Dec 2009
    Location
    Seabrook Texas
    Posts
    33

    Default

    I strongly suggest that you go on line and get a Helms Driveability and Emissions Service Manual for your vehicle. I bought one for my 87 350 pu and it walks you through all the individual diagnostics and troubleshooting for your engine.

    On mine truck there is several things that jump out at me on your question.
    • The IAC (Idle Air Control) valve in the throttle body could be malfunctioning
    • TPS and EMC could be part of the issue.
    • The Electronic Pick Up in the distributor could be sending a false RPM to the EMC and it then is adjusting the idle up as well.
    Regardless the Helms manual will keep you straight and walk you through it step by step.

  3. #3
    Newbie
    Join Date
    Feb 2010
    Location
    Soest The Netherlands
    Posts
    8

    Default

    Quote Originally Posted by Wpowell View Post
    I strongly suggest that you go on line and get a Helms Driveability and Emissions Service Manual for your vehicle. I bought one for my 87 350 pu and it walks you through all the individual diagnostics and troubleshooting for your engine.


    On mine truck there is several things that jump out at me on your question.
    • The IAC (Idle Air Control) valve in the throttle body could be malfunctioning
    • TPS and EMC could be part of the issue.
    • The Electronic Pick Up in the distributor could be sending a false RPM to the EMC and it then is adjusting the idle up as well.
    Regardless the Helms manual will keep you straight and walk you through it step by step.
    thank you for your answer, i will check those 3 points.

  4. #4
    Newbie
    Join Date
    Feb 2010
    Location
    Soest The Netherlands
    Posts
    8

    Default

    thank you for your answer, i will check those 3 points.
    i will search the internet for that manual and order it.

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