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Thread: 2000 GMC 7.4 tuning

  1. #1
    Tuner
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    2000 GMC 7.4 tuning

    I know its not in the supported list. But has anyone ever had to tune or tried tuning the 2000 7.4 liter v8's in the Topkicks? I read on a different site that is was basically a 98 ls1 ecm in these chassis.
    Last edited by Speedracer7g; 06-26-2018 at 01:13 PM.

  2. #2
    Advanced Tuner
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    Read the file, make a small change and try to license it. If it works awesome if not then the pcm isnt supported. Doubtful they will make revisions to support it being it's 18 years old.
    97 ext cab short bed silverado 5.7 411 swap, edelbrock 29135 intake, lightly ported 906 heads milled .035 thou. factory press in rocker studs & rockers, comp 787 retainers & stock locks, ls6 springs. Comp cams 08-503-8 T56 swap

    86 SWB crate vortec 5.7/th350 The wife's truck

  3. #3
    Does it have a black box ECM? Isn't that a coil on plug 7.4?
    1997 Chevrolet K2500 ECSB, 0411, 454, headers w/ Exhaust, MSD, 28lb injectors "Biggin"

  4. #4
    Advanced Tuner
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    If it is coil on plug then it is the 0411

  5. #5
    Potential Tuner
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    As far as I am aware, there are no coil on plug 7.4L
    My 2000 C2500 is an L29 Vortec 7.4L.. Black box ECM, which is supported.
    I've been using HP on it for about 3 years. New to the forum though.

    I am in need of a little advice to perfect some things after a ZZ502 cam swap. Not to steal you're thread, but I was wondering where the appropriate place to ask a few questions. Can someone point me somewhere?

    -Thanks

  6. #6
    Advanced Tuner
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    The L29 454 did not have coil on plug, but the Topkick and Kodiak trucks had the option of an L21 454 which ran the 0411 and coil on plug ignition.

  7. #7
    Advanced Tuner
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    The C3500HDs in the GMT400 body style sometimes had L21s right before the 8.1 was put into them.

  8. #8
    Advanced Tuner
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    Does anyone have an L21 tune? I'm building an L29 with the reluctor wheel from an L21 and coil on plug ignition and would like to have a better starting point.