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Thread: E40 LS2 ported heads and cam off idle pop and banging

  1. #1
    Tuner in Training
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    Oct 2013
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    E40 LS2 ported heads and cam off idle pop and banging

    Hello , this set up is in a 76 camaro with t56 that was dyno tuned using the stock MAF. Makes good power and drives fine just sucks from idle. the car will pop and bang till I rev past 12-1500rpm then its fine (worse under a load). I have a log revving in the driveway. I sent it to the tuner as well just wanted to see what other opinions say. Any and all input is appriciated

    camaro off idle break up 2.hpl



    1976 R3 update.hpt

  2. #2
    Tuning Addict 5FDP's Avatar
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    May 2012
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    Your timing is way low, it's barely above zero or bouncing below zero. Raise the idle timing up to around 18-20 degrees. And cut the overspeed spark correction in half as well, it's allowed to pull too much spark.

    Burst knock should be disabled too.

    And make sure your fuel pressure is staying steady at 58psi. Even in this log just at idle and you stab the throttle with no load the wideband is reporting that it's going lean.
    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
    Vacuum leak?
    Popping is probably from retarded spark, spark is low because air flow is too high but you're seeing 16g/sec when in your tune the base idle airflow is commanding a bit under 7g/sec.
    2010 GXP Maloo ute, LS3, 6L80E.
    MM heads, 240/252@50 solid cam, 12.75:1 compression, 4500 Dominator converter, 3.46 rears.
    Shooting for 10s eventually.

  4. #4
    Tuner in Training
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    Oct 2013
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    5FDP , I tried what you said to no avail, same issue , However i did find a burnt wire so i changed plugs and wires but still no change.

    Xmas I checked for leaks but everything is good , What your saying about the airflow , is that MAF referenced spark? so basically too much airflow and the ecm is looking for less? I would think the ecm would adjust accordingly but I'm no tuner either.