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Thread: forged 5.3 keeps miss firing

  1. #1
    Potential Tuner
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    Aug 2021
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    forged 5.3 keeps miss firing

    okay i have a forged 5.3 has icon flat top .10 over pistons
    eagle 6.100 rods
    tsp torquer v2 cam
    cnc ported 243 heads
    ls6 intake
    36lb injectors
    3200 yank stall
    4:10 gear
    basic bolt ons
    i am new to ls and tuning ive been sbc guy forever so any help would be nice
    camaro base tune.hptfirst run.hpl

  2. #2
    Tuning Addict 5FDP's Avatar
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    May 2012
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    Rogers, MN
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    When is it misfiring?

    The tune needs to have the cylinder volume fixed because it still says it's a 5.7 and not a 5.3. Your injector data is not corrected yet, it's still says it's running the factory 28lb/hr injectors.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
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    Aug 2021
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    this is just what the dyno guy did around me and its been missing ever since so i figured id try it my self dont really know how to change that stuff

  4. #4
    Senior Tuner TheMechanic's Avatar
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    Jan 2014
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    Single cylinder or random/all? If single it is time for a 1. compression test. 2. coil, wire, plug swap. 3. Injector pressure drop test. If random it's time to bust out the scanner and see if you are rich, lean, or not firing at the right time

  5. #5
    i was told that I needed to do a case relearn on my 8.1 to cure the misfire issue, but I do not have all inputs correct, what ever is going on I cant get it done, yet!! that is on the list to fix soon.

  6. #6
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    Aug 2021
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    okay so went threw and changed it to 5.3 have just a idle long car mis fires pretty much when cold or hasnt been rapped up i dont have a afr gauge so idk if im running lean or not and i dont know if the timing is to advanced come to find out it was just stock injectors gotta love getting somone elses lie5.3 change.hpl

  7. #7
    Tuner in Training
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    Jan 2007
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    Quote Originally Posted by Shade_tree_mechanic View Post
    i was told that I needed to do a case relearn on my 8.1 to cure the misfire issue, but I do not have all inputs correct, what ever is going on I cant get it done, yet!! that is on the list to fix soon.
    @Shade_tree_mechanic i'm completely baffled as to how it worked, but the crankcase relearn cured my misfires.

    @rjennings fire up the engine in the dark & look for arcs around the plug wires