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Thread: 416 LS3 stroker start up issues

  1. #1
    Advanced Tuner
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    Apr 2007
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    416 LS3 stroker start up issues

    I am having some issues with starting that track engine, it is an LS3 block based 416ci with a big 253/259 cam.

    it idles decent at 1050 rpm, but does not want to start although fuel and advance are not too far. Cold starts absolutely fine. Did the minimum idle air tuning a few times and numbers are not far off, when starting with hot engine it needs help with the throttle and sometimes 3 - 4 attempts before it catches, then it runs 10-15 seconds pretty rich at low rpm 550 - 650 and then settles at target idle rpm with correct AFR in the high 13's. No stalling thereafter, no matter how hard you blip the throttle, steady idle. But, the closer my minimum airflows get, the harder it starts!

    what really puzzles me is that the rearmost cylinders tend to foul up, the front ones are fine and I can't find anything wrong, all checks out. Also weird, the left cat likes to glow, the right side not but AFR are decent on both sided. If I do a cylinder balance test all cylinders are within 99 and 100%. I literally took everything apart and checked and rechecked but still does it.

    injectors are stock LS3 and use stock injector data too.


    so far only part throttle up to 4000 is dialed in and idle a bit so pls disregard anything above, right now I am fighting with starting only. Usually these things fire to life instantenously, this one not.

    what is seems wrong with that hard starting? I can richen up, lean down, more advance or less hot starting is awful and does not really seem to have muchn effect.

    suggestions?
    Last edited by ccrp; 03-07-2012 at 03:00 PM.

  2. #2
    Advanced Tuner oakley6575's Avatar
    Join Date
    Aug 2011
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    421
    any update to this?
    2003 Chevy Silverado Daily Driver, 408 Iron Block,
    LS3 Heads/Intake, 231/239 114, 4L80e, Yank SST 3200.

  3. #3
    Advanced Tuner
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    Apr 2007
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    yes. In the end we changed to another cam and even if it is more race oriented all those issues went away. Either cam was misground or something else with it.

    nothing else done, with that cam engine responded to any and every programming change as usual, with the first one it did not