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Thread: Looking for PCM P/N for L21 454 (99 P12 RV Chassis)

  1. #1
    Lifetime Member N0DIH's Avatar
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    Default Looking for PCM P/N for L21 454 (99 P12 RV Chassis)

    Anyone ever tune one and know what PCM this is?

    It is a 454 that appears to be a L29 but has coil on plug and is called the L21.

  2. #2
    Lifetime Member GMPX's Avatar
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    At a guess, if it is a coil on plug then it probably is an LS1 style PCM, in that case, the 1999 PCM was Service # 09354896.
    Try looking the VIn up on CalID and let us know what the O.S number is.

    Cheers,
    Ross
    I no longer monitor the forum, please either post your question or create a support ticket.

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    Lifetime Member N0DIH's Avatar
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    I don't have the PCM, but I have a 99 K2500 Burb with the 454 and would like to go coil on plug.

    Just found out about the 12200411 swap, is that a coil on plug setup? It is used on many LS v8's, or is it how it is configured/programmed?

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    Lifetime Member GMPX's Avatar
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    Yes, it's the replacement to the one I listed. That would work.

    Cheers,
    Ross
    I no longer monitor the forum, please either post your question or create a support ticket.

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    The 12200411 PCM can run either a dist. Vortec or a coil on plug LS engine. To run coil on plug you would have to adapt a 24 tooth crank reluctor wheel to your engine, probably on the balancer. It can be done, but it would be a pretty big project. The 411 PCM is a much better PCM than the Black box PCM.

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    Lifetime Member N0DIH's Avatar
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    I thought the Vortec's already had the 24x res crankshaft position sensor. Is the output unique compared to the LSx V8's?

    Is adaptable to the 454? Being the 99 454 RV had it?

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    I am not familiar with the RV 454. On the 96-02 applications that used the small block Vortec with a distributor, the engine used a 4x reluctor wheel in front of the crank sprocket for the timing chain.

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    Lifetime Member N0DIH's Avatar
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    I'll check what the 454 has, but I think IIRC everything is same as the L31

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    Default The L21 Vortec...

    I've got one. Let me know if I can help.

    Steady Eddie
    L21/Allison

  10. #10
    Lifetime Member N0DIH's Avatar
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    I was digging in the P12 Chassis FSM and the L21 has a unique front cover that the L29 doesn't have, with a crankshaft sensor in it.

    So, if was to convert to a 0411, running like the L31 was run on it, then later add the L21 front cover/crank sensor, would it be fairly easy to switch over to COP? I'll have to do some digging to get the proper L21 valve covers and the L21 front cover with sensor. Hopefully it isn't a unique crankshaft, but somehow a tone ring needs to be installed most likely.

    I would think the COP ignition is much more accurate and potential for more power at higher rpms with the coils spending more time in saturation than with the old single coil/HEI setup.

    Quote Originally Posted by Lextech
    The 12200411 PCM can run either a dist. Vortec or a coil on plug LS engine. To run coil on plug you would have to adapt a 24 tooth crank reluctor wheel to your engine, probably on the balancer. It can be done, but it would be a pretty big project. The 411 PCM is a much better PCM than the Black box PCM.

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