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Thread: Knock when letting clutch out and applying gas

  1. #1

    Knock when letting clutch out and applying gas

    I have been pulling timing from the low end cells to try and get the knock to go away when i take off and let the gas out. Im not launching hard just a gradule release of the clutch and gradule application of the gas. I keep getting knock and cant tell if its false knock or not. I got the VE table to +\-3 and have been tuning the MAF. In the attached tune the LTFT&STFT are disabled, tuning MAF on a LM-1 wideband. But cant tell why im getting the knock. I never hear it when it shows on the scan. How the hell can i tell if its false, real, and/or fix it??
    99' T/A WS6 M6 no emmisions
    Stock bottom end, Edelbrock LT stepped 1 3/4- 1' 7/8, ORY to dump in front of rear axle, LS6 intake, LS6 hand ported heads, LS6 ported Oil pump, Double roller timing chain, Cam 236/242 .601 .610 on 114 lobe, all supporting head mods to support cam, stock rockers, stock lifters, 60# injectors, stock MAF

  2. #2
    Also to add to this, the tune is a Beta and the lean spikes you may see during shifts are the back-flow of exhaust going into the pipe due to having it dump in front of the rear end, i know what they are, that is not a huge lean spot and also it does not appear until i go from 1st to 2nd and i have not had any hard knock through the gears or WOT. Im trying to figure this out before i start adding timing to the big end and WOT.
    99' T/A WS6 M6 no emmisions
    Stock bottom end, Edelbrock LT stepped 1 3/4- 1' 7/8, ORY to dump in front of rear axle, LS6 intake, LS6 hand ported heads, LS6 ported Oil pump, Double roller timing chain, Cam 236/242 .601 .610 on 114 lobe, all supporting head mods to support cam, stock rockers, stock lifters, 60# injectors, stock MAF

  3. #3
    Senior Tuner
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    Feb 2009
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    When I look through your scan, then your file in comparison with a 2002 file, I notice that all of the tip-in values are higher on a 2002 file. Reading the descriptions in hp tuners, these values have to be exceded for it to be considered knock. I would suggest copying the values from a 2002 file for tipin and see if the problem goes away.

  4. #4
    Well what are the values? I have a 99 and am still working off of the stock 99 values for tip in
    99' T/A WS6 M6 no emmisions
    Stock bottom end, Edelbrock LT stepped 1 3/4- 1' 7/8, ORY to dump in front of rear axle, LS6 intake, LS6 hand ported heads, LS6 ported Oil pump, Double roller timing chain, Cam 236/242 .601 .610 on 114 lobe, all supporting head mods to support cam, stock rockers, stock lifters, 60# injectors, stock MAF

  5. #5
    Senior Tuner
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    Feb 2009
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    1,931
    Download a stock 02 out of the repository.

  6. #6
    I have an 02 tune off of the repository and its the same as mine. I still need the main questions answered, is it real knock, if so why and how do I fix? I know how to adjust the tip in sensitivity.
    99' T/A WS6 M6 no emmisions
    Stock bottom end, Edelbrock LT stepped 1 3/4- 1' 7/8, ORY to dump in front of rear axle, LS6 intake, LS6 hand ported heads, LS6 ported Oil pump, Double roller timing chain, Cam 236/242 .601 .610 on 114 lobe, all supporting head mods to support cam, stock rockers, stock lifters, 60# injectors, stock MAF

  7. #7
    Senior Tuner
    Join Date
    Feb 2009
    Posts
    1,931
    I dont think so. Pretty hard to get knock where you were getting it. Picking up something from clutch grabbing or something to that effect I think.

  8. #8
    Ok well i increased the Tip-in to 13 below 5200rpm, wondering if that is enough or should i go higher? Should i increase the number by the amount of false knock that im getting? Also could someone take a look at my VE table here, i noticed that once i was done with tuning the VE there is a dip in the numbers at 2400 RPM's, im just wondering what would cause this, could it be the cam or the set up that i have? While im tuning the MAF right now it seems to want to do the same thing between 7000Hz and 7500Hz want to level out and not continue to climb like i have been told it should and everyone else does.
    99' T/A WS6 M6 no emmisions
    Stock bottom end, Edelbrock LT stepped 1 3/4- 1' 7/8, ORY to dump in front of rear axle, LS6 intake, LS6 hand ported heads, LS6 ported Oil pump, Double roller timing chain, Cam 236/242 .601 .610 on 114 lobe, all supporting head mods to support cam, stock rockers, stock lifters, 60# injectors, stock MAF