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help with miss on 99 K2500 with 5.7L

Discussion in 'Performance & Fuel' started by 99blueburb, Jul 24, 2007.

  1. 99blueburb

    99blueburb New Member

    Not sure if this can be here.

    I have a 1999 OBS burb with 131K miles on it. I have a miss between 1500 - 2200 rpms. There is no code or SES light. I put it on a scanner and it does not show a miss. It is not in the trans, as I can get it to miss while in park and rev up to 2500.
    I have replaced the following:
    tune-up (plugs/wire/cap/rotor)
    coil (2 different brands)
    fuel filter
    fuel pump
    O2 sensor
    TPS sensor
    seafoam in gas tank to clean injectors
    and swapped from the old poppet valve spider to the ungraded injector spider

    Still can't find miss.
    Any help?

    Basically stock, has flowmaster cat-back, K&n filter, and a PCM4less computer. I have even put the stock computer back in. Same problem.
    Motor still pulls strong to 5K rpm. If I am under light throttle and lite load, that is when the miss occurs. If I give it more gas, it goes away.
  2. GaryL

    GaryL Epic Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    You might try doing a compression test, you could have a cylinder that down a little bit. Also, are you hearing any valve train noise? Could be a bad lifter or cam going flat. Just some ideas.
  3. CaJuN625

    CaJuN625 New Member

    miss at speed

    Sounds like a bad valve spring or seat, personally.
  4. Toymyster

    Toymyster Rockstar 100 Posts

    Also check your fuel pressure, your fuel pressure regulator might be out of range!!!
    Last edited: Sep 3, 2007
  5. Wayne S

    Wayne S New Member

    Check the gasket around the throttle body for leaks, might just need a $0.25 gasket. I had that problem on my previous Suburban (1989 with TBI 350), and it was doing the same high idle that you described. Worth a shot.

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