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Thread: constant knock

  1. #1
    Tuner in Training
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    Apr 2018
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    constant knock

    Have a 2008 tahoe that is showing constant knock as soon as you start driving. Have replaced knock sensors and lowered timing in spark tables and still have knock it shows its operating out of the low octane table entirely with the knock learn at 1 cant seem to figure it out fueling seems to be alright as well any help is appreciated log and tune attached below thanks i also logged each individual cylinder as well showing knock in all
    RUS STOCK FILE hi_lo octane 1.hpt18-10-30 10-12-07.hpl

  2. #2
    Tuning Addict 5FDP's Avatar
    Join Date
    May 2012
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    Rogers, MN
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    13,533
    Does it do it with say 93 octane fuel?

    If it was the same way, then to me that seems to be false knock and you could make the knock sensor less sensitive.
    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
    Tuner in Training
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    Apr 2018
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    18
    Haven't tried a higher octane fuel yet will have him fill up with some and give that a shot

  4. #4
    your missing a ton of info to diagnose.
    you must have 02 b1s1 ob2s1 o2b2s1 o2b1s2 need mv on each incase its too lean ltft and stft also to check for clogged cat
    need maf reading map sensor in kpa knock retard on every cylinder incase its just one or two cylinders
    you need ltft bank 1 and 2 spark advance.
    knock on each cylinder yes evey cylinder if you have a bad bearing one cylinder will knock if you have a back main front 2 might knock.
    engine coolant temp
    cylinder airmass calculation
    fuel pressure in case your running low pressure and its not spraying properly
    plus oem tune with current tune and mods.
    im pretty sure that is all of the info I need.
    intake air temp
    also commanded fuel pressure if applied
    Last edited by jpierro79; 11-02-2018 at 12:34 AM.