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Thread: Knock with LS7 tune

  1. #1
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    Knock with LS7 tune

    So I am self tuning my C6z. Car has headers/x-pipe and a wideband, vararam intake, oil catch can, running new TR6IX plugs, and car is on 93 pump gas. I am seeing some knock in the logs and wanted some input from people with more knowledge. Car is running stock timing and I am still seeing light knock and not sure if that is normal or not. Car is running good and doesn't have any noises that I can hear. Is it normal to have to lower stock timing on LS7s? Should I try that first and see if things go away or add some octane booster and see if that helps? I have attached a log of mainly cruising but some half WOT pulls that I see knock on.

    I have tuned MAF, VEE, and PE table. LTFTs are +-3 so that looks good and WOT is around 12.4-12.7 from what I can see in my logs.

    Any input is helpful! Thanks

    Z06Headers_PE5_VVE2_MAF6_SKIP_BurstKR0_No02_DFCO-Spark.hpt
    knock2.hpl

  2. #2
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    So I removed -4 from pretty much the full load spark table to see how the KR reacted. It looks like there is much less KR then the stock table but I am still getting -1 a few places. This just seems like a a lot of timing being pulled for a stock map on 93. Does this seem like a tune issue? mechanical issue? or is it normal to see this and im just a noob. Not sure where to look next or what to run for timing on the tune.

    Thanks for any help. I have attached the new log and tune with lowered timing

    spark_retard_test.hpt
    knock3.hpl
    Last edited by steelers743; 06-02-2020 at 07:49 PM. Reason: adding logs

  3. #3
    Senior Tuner Frost's Avatar
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    I tune knock sensors along with the spark on the dyno. You can't tell what's real just riding around, and they start out uber sensitive if all KS settings are OEM (after a flash).
    Steve Williams
    TunedbyFrost.com


  4. #4
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    Ill just leave it as stock timing and that sounds like a safe bet.

  5. #5
    I believe i can help you out my friend, I also tune my c6z and i faced this for a while in the beginning and kep reducing spark only to find out, it is not what I was thinking. You are monitoring knock retard, go into vcm scanner and add PID for burst knock and each cylinder knock retard, as well as total knock retard. Now when you see it knocking, go to the pids and see if it is in a cylinder or burst knock. burst knock is a preventive measure based on big changes in torque, notice on your second post inside the tune, your knock comes when changing the throttle and jumping kpa up to 80-100, this is clear signs of pre programmed preventive burst knock.
    Add the additional pids and put your spark settings back to where they were, if it is knock in the cylinders reduce the spark, add methanol, go e85, get a fuel cooler or go to a colder spark plug.
    if my hunch is correct and it shows up under burst knock, simply reduce your burst knock sensitivity. I still allow my car to barely reduce spark if it thinks its necessary, it happens whenever i stomp it from 3k it reduces spark by .1-.5 degrees, and its pure burst knock. I hope this helps.

  6. #6
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    Ill that thanks! I thought I 0rd out burst knock in the tune. Will make sore more logs with additional PIDs to see if i can see what cyl its angry with

  7. #7
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    Hmm just went back to stock timing and did another drive. Significantly less KR this time, avg all under 1. The KR did always show up under cly 5. I did fill the tank so possibly the gas I had in it was just a bad batch before. I'll keep an eye on it and report any of my findings. Also I made sure to turn TC off this drive, when TC pulls timing does that show up as KR?