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Thread: Knock Counts Seem High, But no Audible Knocking

  1. #1
    Fuel Injected!
    Join Date
    Jan 2018
    Posts
    41

    Knock Counts Seem High, But no Audible Knocking

    See attached datalog.

    I have tuned out the knock retard for performance sake, and I have since modified my tune to take 1-2 degrees out at the points where the highest counts are per Dave's spreadsheet for WBO2 tuning.

    Background, Stock L31 Longblock w/ Performer RPM and TBI adapter. Running ~ 18PSI of fuel pressure. Nothing special. Pulling the timing at the points where I did put the timing table at those points about in line with the Stock 98 Vortec timing table available on this site.

    Does anyone have any suggestions on this? I am using a stock knock sensor and ESC module for a 95 TBI Suburban. I have read before that these may need to change for roller cam? Also read that perhaps over tightening the knock sensor (which I replaced) could cause false knock?

    Dave suggested I may have an issue with my distributor, can anyone else confirm or has anyone had a similar issue?
    Attached Files Attached Files

  2. #2
    Fuel Injected! woody80z28's Avatar
    Join Date
    Nov 2011
    Location
    Walton, NY
    Age
    38
    Posts
    242
    I'm also getting knock counts and retard on my roller Vortec TBI build. Power is down, too. I built it in '11 and the power recently dropped off.

    The weirdest thing is my log shows 10* less than my table in the bin, and I have the main spark bias set to 0. I had a code 43, but the resistance on the sensor and volts on the wire tested perfect, so I turned off the code. I'm wondering if the ECM still "sees" the code and retards timing.
    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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