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Truck has low idle/knocks off

Discussion in 'GM Powertrain' started by kgibson181, Jun 18, 2010.

  1. kgibson181

    kgibson181 Epic Member 5+ Years 1000 Posts

    For the past two weeks now my truck has been only idling around 300-400 rpms where as before it would idle at a smooth 900-1000 rpms. Also if I am driving and come up to an intersection or a stop light, as I slow to a stop the truck will sometimes knock off completely because it begins to try and idle so low. So basically I am asking what you might think the problem is with my truck. Friend of mine told me it could be an idle sensor but I want to hear some other opinions before replacing it.

    Thanks and all the truck info is in the sig.
  2. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    Is the CEL on??? And the Idle Air control valve, can be cleaned.. Most likely there is a chunk of carbon built up in it.. So you remove it and clean out the passages..and put it back on, and reset youur computer..
    If the CEL is on you will want to check the codes before you do anything however...
  3. k.daddy1

    k.daddy1 Rockstar 100 Posts

    Pull the vaccuum line off the fuel pressure regulator on top of the motor and see if you have gas coming from it. If you have fuel present the regulator is bad.
  4. kgibson181

    kgibson181 Epic Member 5+ Years 1000 Posts


    Could you tell me how I would know if the CEL is on? And where exactly is the idle air control valve located?

    Thanks
  5. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    Ok the CEL is the Check engine light.. Sorry... And the IAC is mounted on the throttle body....
  6. kgibson181

    kgibson181 Epic Member 5+ Years 1000 Posts

    Wow that check engine light thing just made me feel like an idiot lol. But yeah thanks man for the advice, took it all apart and what do you know huge buildup around the outside of the valve. Cleaned it up nice and put it back on...back to running normal. Thanks again
  7. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    No problem.. You might want to consider doing a seafoam treatment.. If you search the forums there is a ton of reviews and info on it.. It might help to get it running even better.
  8. kgibson181

    kgibson181 Epic Member 5+ Years 1000 Posts

    yeah i'll have to do that, seafoam is good stuff. Used in all of my previous bikes and keeps them pristine.

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