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Thread: False knock...I'm pretty sure. I hope?

  1. #1
    Fuel Injected! woody80z28's Avatar
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    False knock...I'm pretty sure. I hope?

    Couple things I've noticed with recent logs. I'm getting spark retard sometimes but I don't think I have knock. I've seen it pull as much as 8* timing.

    It is most prevalent when letting out the clutch during takeoff and on gear changes, and I've even seen it during DFCO. But I've intentionally lugged the engine at 2000rpm and high load in 5th up a hill and I get nothing. WOT gets nothing at higher RPMs once the retard has decayed after launch and gear changes.

    I'm thinking the couple possible contributors if it is false knock is my basically solid (billet/poly) engine and trans mounts, and I've noticed the engine just seems noisier than it used to after a cam change with heavier valve springs and bigger injectors. The engine itself always has me second guessing its health because it sounds like lifters ticking or lack of oil...but everything checks out and it just survived a 2500mi road trip last week. haha

    Here are a couple logs and the ADX I'm using if anyone would like to check it out. Once I run this tank of 87 out I was thinking of pumping in 93 just to see if it changes at all...just to be sure it's false.

    If it is false, how do I desensitize the sensor? A friend of mine suggested teflon tape on the sensor threads rather than liquid sealant into the water jacket. I see a maximum spark retard vs rpm table I could zero out, but I'd like to keep some functionality of the knock sensor if possible.

    Any help is appreciated. Thanks
    Attached Files Attached Files
    80 Camaro Z28 - 550hp AFR 383 / T56 6spd (Holley HP EFI)
    91 Beretta "SS" - 260hp 3400 MPFI / HM282 5spd (7730/$A1) sold! for crazy money...but I miss it
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd (7427/$0D) gone but not forgotten
    96 Beretta "T56" - 4.8 LS RWD swap / 6spd (0411/2156)
    01 Silverado 2500HD - stock Vortec 8.1 / ZF6 6spd (0411/8322)
    https://www.youtube.com/c/GEARHEADdezign

  2. #2
    Fuel Injected! woody80z28's Avatar
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    Nov 2011
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    Walton, NY
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    Filled it up with 93 and my knock looks the same as far as I can see. I'm getting false knock on shifts and DFCO, but also at like 10% TPS and 25 MAP on level ground in 3rd gear cruise. That one seems weird, but I don't think there's any way it's true knock...especially on 93 now.

    I can try teflon taping the sensor to "desensitize" it. I also thought about changing the max knock retard from 15 to 0.5deg, so I can still see it easily in a log, but essentially remove it. Obviously I'd rather have it hear actual knock and be able to retard until it goes away, but I think it's reasonably safe.
    Attached Files Attached Files
    80 Camaro Z28 - 550hp AFR 383 / T56 6spd (Holley HP EFI)
    91 Beretta "SS" - 260hp 3400 MPFI / HM282 5spd (7730/$A1) sold! for crazy money...but I miss it
    94 Silverado Z71 - 300hp Vortec 357 TBI / NV4500 5spd (7427/$0D) gone but not forgotten
    96 Beretta "T56" - 4.8 LS RWD swap / 6spd (0411/2156)
    01 Silverado 2500HD - stock Vortec 8.1 / ZF6 6spd (0411/8322)
    https://www.youtube.com/c/GEARHEADdezign

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