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Thread: ls1 misfire problem

  1. #1
    Junior Member
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    Default ls1 misfire problem

    i have a vz ss ls1 233/242 110lsa and now have a misfire i have seems to be on idle and partial throttle upto about 4000rpm if i accelerate it feels like a vibration through the driveline it doesnt completely drop out any cylinders but i carnt put my finger on it. it seems to be worse when the engine is warm and but it comes and goes while driving. the mixtures are fine but the plugs are black except for 2 cylinders show normal. i have changed the plugs tried a smaller gap also changed leads and checked all conectors coils appear to be ok and injectors and fuel system are definatly good. im not getting any misfire codes have also tried a case relearn. the engine is healthy all cylinders are 180psi and i have between 4-7% cylinder leakage.
    i have tried adding and taking fuel with the scan tool with no luck seems to get worse the leaner it runs and rich makes no difference added timing it makes it worse and taking timing does nothing if i hold the revs up in neutral i can here the misfire very badly. does anyone have any ideas what this problem could be i am at the point of giving up on this car as i am forever spending money on it and havent even had the chance to enjoy it yet

  2. #2
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    Default

    How much do you want for it?

  3. #3
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    Are the lifters good? Are the push rods hitting the head? Right springs? .......... "They should be, its all new," is not a valid answer.

  4. #4
    Joe (Moderator) joecar's Avatar
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    Post logs and tune.

    ~ posted by phone ~

  5. #5
    Joe (Moderator) joecar's Avatar
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    Did this just start happening...?

    ~ posted by phone ~

  6. #6
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    Lifters and springs were recently changed also its been happening for a while now I have only just realised what's actually going on thought it was just a deivline vibration but it's definitely a misfire. What pids should I log

  7. #7
    Lifetime Member Chevy366's Avatar
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    Are your plugs to cold in the heat range area?
    2005 1500 HD , Custom OS3 SD tune .
    2006 Trailblazer
    Dinosaurs and Plants gave their lives so that we may drive , long live fossil fuel .

  8. #8
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    No they are standard

  9. #9
    Lifetime Member 5.7ute's Avatar
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    Check the ground points on the heads. Front of head drivers side, rear on passenger side.
    The Tremor at AIR

  10. #10
    Lifetime Member Chevy366's Avatar
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    Yeah, body grounds too, PCM and such.
    2005 1500 HD , Custom OS3 SD tune .
    2006 Trailblazer
    Dinosaurs and Plants gave their lives so that we may drive , long live fossil fuel .

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