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Thread: misfire problems

  1. #11
    Joe (Moderator) joecar's Avatar
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    The misfire algorithm may or may not pinpoint the right cylinders...

  2. #12
    Lifetime Member Gregs's Avatar
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    Check each coil and plug wire using something like this: KD2756.
    will do, i got one in the shop

    03 Silverado 5.3 ECSB 4x4 Z71
    Comp Cam 206/212 .515/.522 112 lSA, hardened rods with LS9 springs

    2010 Tahoe VVT AFM 5.3
    Stock for now

  3. #13
    Lifetime Member Gregs's Avatar
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    final update for the day:

    tested and i have good spark. I pressure tested the coolant system and it checks out. Went on a test drive and it was chugging hard. couldn't get over 40 mph and it smelled like bad catalytic converter smell. Now that i think back about all the problems, a bad cat makes a lot of sence. we'll know for sure once they ummm...fall off accidentally

    03 Silverado 5.3 ECSB 4x4 Z71
    Comp Cam 206/212 .515/.522 112 lSA, hardened rods with LS9 springs

    2010 Tahoe VVT AFM 5.3
    Stock for now

  4. #14
    Joe (Moderator) joecar's Avatar
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    You can remove the front O2 sensor and see if that frees up the engine...

    If you have an exhaust pressure gauge you could measure the pressure due to the cat, should be no more than 1-2 psi.

    edit: for example http://www.tooltopia.com/star-tu-29pb.aspx
    Last edited by joecar; June 24th, 2010 at 07:55 PM.

  5. #15
    Lifetime Member Gregs's Avatar
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    removed the o2 before the cat and it ran so much better. i'm glad i finally found the culprit

    03 Silverado 5.3 ECSB 4x4 Z71
    Comp Cam 206/212 .515/.522 112 lSA, hardened rods with LS9 springs

    2010 Tahoe VVT AFM 5.3
    Stock for now

  6. #16
    Joe (Moderator) joecar's Avatar
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    How many miles on the cat...?

  7. #17
    Lifetime Member Gregs's Avatar
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    about 79000

    03 Silverado 5.3 ECSB 4x4 Z71
    Comp Cam 206/212 .515/.522 112 lSA, hardened rods with LS9 springs

    2010 Tahoe VVT AFM 5.3
    Stock for now

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