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Thread: 4.8 throttle problem

  1. #1

    4.8 throttle problem

    hey havent been online for a while but i got and issue. i got a 4.8 5speed and its starting to act up quite a bit. when i let of the gas to shift or just slow down alot of the times its like the motor doesnt want to rev down. it will stay at the same rpm for a second or so then slowly rev down. also when im driving at a steady speed and let off the throttle it will sometimes very quickly almost violently rev down. well thats the best way i can describe it at least lol. any ideas

  2. #2
    What year? If its a drive-by-cable its probably a sticking iac valve, its a little cylinder on the side of the throttle body held on my two screws (some years had allen some had torx), take it off and hose it down with electrical parts cleaner, then hose down its little passage till clean as well as the rest of the tb, make sure there isn't a ring built up.

    If its a later model with drive-by-wire then it sounds like a throttle cracker problem (tc is a table in the pcm that works as both idle air control, and a few other things), is the truck tuned? Tuning can mess of the tc settings. I'd clean the throttle body just in case.

    It could also be a vacuum leak, bad MAF, the engine dropping out from under you can be fuel related.

  3. #3
    its an 05 drive by wire with no tune. ill look into the things u suggested thanks

  4. #4
    Join Date
    Mar 2009
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    Tyler, TX
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    If it drives funny sometimes, your foot pedal may be bad.Its just the same as a TPS gone bad.
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    www.tjc.edu

  5. #5
    Quote Originally Posted by molitor View Post
    If it drives funny sometimes, your foot pedal may be bad.Its just the same as a TPS gone bad.
    that explains alot.. i dont know nothin about this electric throttle stuff, done alot with carbed motors and cable throttle motors but this is all new. mechanic at work told me to check tps so i popped the hood looked at the throttle body and um yea got confused lol

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