Thread: false kr where is it comeing from

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  1. #1 false kr where is it comeing from 
    GT Level Member jrb1027's Avatar
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    Hey guys, ive posted a few times on here about kr issues but never solved the problem.

    First off it has been tuned less than 3 months ago by prj, it didnt change much, but did clean up the kr at shifts.

    Symptoms-I show very high kr (as high as 15kr if i dont let up) it happens when i give more than

    half throttle under 3k rpm, above that and there is 0 kr. I assume its false because it probably would

    have blown up by now if it wasnt.

    if you need more information just ask.

    btw i was told it could be the exhast it has slp headers i had it on a lift and inspected the downpipe i can not see any

    physical rubbing in the tunnel.
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  2. #2 Re: false kr where is it comeing from 
    Turbo is the way to go. REDCRAPGP's Avatar
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    What's the condition of your motor mounts?

    Also check to make sure the sway bar isn't hitting the header..you can flip it around just to be sure that there's plenty of clearance.
    Squirrels are my engine. I need a Ford Regal
    04 Comp G.
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  3. #3 Re: false kr where is it comeing from 
    GT Level Member jrb1027's Avatar
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    prj told me the mounts looked good i looked at them and couldnt see any cracking, I dont think the

    swaybar is touching because i didnt notice rub marks when i inspected it. Its has gmpp bars do they

    have same clearance issues, its lowered too about 1.5in.
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  4. #4 Re: false kr where is it comeing from 
    Moderator dsmuts's Avatar
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    Just flip it and see
    98 GTP modded 1.9's, sd headers, 3.4", zzp 1.0 230K miles scrapped.
    04 Comp G zzp stb's, UMI ta's, Speedbuilt sways, bully flo heads, XP, zzp headers, fsic, thrasher shift kit, 60#, 2.6" corsa 2.5", Inferno hood
    01 gt z7 turbo tep trans zzp motor
    08 g8 gt cam exhaust 11.87@118
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  5. #5 Re: false kr where is it comeing from 
    GXP Level Member darkhorizon's Avatar
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    no amount of noise will cause this... Its a wiring or sensor failure. I tried to fix this in the past with a case learn, ICM swap, but honestly I was never able to fix it.

    I ended up disabling the knock senesors in the PCM under 3000 RPM completely... Oh well...
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  6. #6 Re: false kr where is it comeing from 
    GT Level Member jrb1027's Avatar
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    really? thats seems like it could be detrimental, but i may have to do that.
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  7. #7 Re: false kr where is it comeing from 
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    According to alleged gurus on this board, there is no such thing as false knock.
    However, in the real world, something in the engine bay is likely resonating at the same frequency that the knock sensors detect knock below 3k.

    Does it happen in all gears?
    Is it only when the TCC is locked? IE: When you're cruising on the highway and load the engine to go up a small incline?
    What mods do you have?
    Check the trans mount and the bottom motor mount located on the underside of the engine near the passenger tire. They can collapse.
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  8. #8 Re: false kr where is it comeing from 
    The Blue One blueguy's Avatar
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    lol guru's. I'm a firm believer in burst/false KR, buddy.

    I ALWAYS tell people to check downpipe clearance to the front sway bar and mount condition or anything else that could be making contact giving the knock sensor a false reading.
    Sold WBody's: '03 Blue GTP/'98 Green GTP/'98 Silver GT/'05 GXP
    '99 Chevrolet Silverado Classic Z71 4x4 - K&N Intake/Gibson Exhaust #TRUCKTHINGS
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  9. #9 Re: false kr where is it comeing from 
    GT Level Member jrb1027's Avatar
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    it does happen in all gears.

    I believe its only when the tcc is unlocked, doesnt it lock at 2800 or so

    Mods- cai, headers, no cat, no res, 3.4 on genv, 1.8 rollers, every suspension upgrade

    I will double check the mounts i had it on a lift not too long ago when i examend them i did not see any cracking
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  10. #10 Re: false kr where is it comeing from 
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    The TCC will lock when you're cruising. If you're going 50mph in 4th gear, it'll lock up at like 2000rpm.
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  11. #11 Re: false kr where is it comeing from 
    GT Level Member jrb1027's Avatar
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    ok i think i understand, I dont think the tcc being locked or unlocked has any effect on the kr.
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  12. #12 Re: false kr where is it comeing from 
    GT Level Member jrb1027's Avatar
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    getting back to what darkhorizon mentions, he suggest I remove the kr sensor from pcm under 3k, does anyone second that.
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  13. #13 Re: false kr where is it comeing from 
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    Quote Originally Posted by jrb1027 View Post
    ok i think i understand, I dont think the tcc being locked or unlocked has any effect on the kr.
    This makes me believe even more that it's false knock.
    Which is a real thing, clearly lol.

    I wouldn't turn the sensor off below 3k... I'd do everything I could to figure out why it's doing it first.
    It could even be noise from the transmission, resonating at specific RPM.
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  14. #14 Re: false kr where is it comeing from 
    Moderator dsmuts's Avatar
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    How would you go about disabling the knock sensors under a certain rpm?
    98 GTP modded 1.9's, sd headers, 3.4", zzp 1.0 230K miles scrapped.
    04 Comp G zzp stb's, UMI ta's, Speedbuilt sways, bully flo heads, XP, zzp headers, fsic, thrasher shift kit, 60#, 2.6" corsa 2.5", Inferno hood
    01 gt z7 turbo tep trans zzp motor
    08 g8 gt cam exhaust 11.87@118
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  15. #15 Re: false kr where is it comeing from 
    Moderator dsmuts's Avatar
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    nm i figured it out.
    98 GTP modded 1.9's, sd headers, 3.4", zzp 1.0 230K miles scrapped.
    04 Comp G zzp stb's, UMI ta's, Speedbuilt sways, bully flo heads, XP, zzp headers, fsic, thrasher shift kit, 60#, 2.6" corsa 2.5", Inferno hood
    01 gt z7 turbo tep trans zzp motor
    08 g8 gt cam exhaust 11.87@118
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  16. #16 Re: false kr where is it comeing from 
    GT Level Member jrb1027's Avatar
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    If my mounts are good, sway bar isnt touching exhast, and trans dipstick is not touching anything, where do i go from here? Do you

    have any more suggestions, is it possible to check for trans resonating?
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  17. #17 Re: false kr where is it comeing from 
    GT Level Member jrb1027's Avatar
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    on a side note (dsmuts) we live pretty close to each other
    Last edited by jrb1027; 11-20-2013 at 06:28 PM. Reason: grammar
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  18. #18 Re: false kr where is it comeing from 
    The Blue One blueguy's Avatar
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    Might not be touching at a standstill, but touching under load, which is where the KR is coming from.

    Also, mounts could appear fine, but you need to actually remove the wheel flashing and inspect them closely.

    I'm sure one of the two is the culprit.

    They're known for blowing out and failing, even if fairly new. That's why you should either get poly lowers and rattle your teeth apart, or get solid rubber replacements, you just want to avoid the factory fluid filled replacements.
    Sold WBody's: '03 Blue GTP/'98 Green GTP/'98 Silver GT/'05 GXP
    '99 Chevrolet Silverado Classic Z71 4x4 - K&N Intake/Gibson Exhaust #TRUCKTHINGS
    '12 Buick Regal Turbo - ZZP CAI/20% Tint/HID's
    '89 Ford Mustang LX Notchback - LM7 5.3, 4L80, 9", HX40
    '04 Chevrolet Corvette MRM A4/LS1 - TSP LT's, 3"O/R X, AFE S2 CAI
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  19. #19 Re: false kr where is it comeing from 
    Moderator dsmuts's Avatar
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    If you wanna come over sometime I could look it over for you.
    98 GTP modded 1.9's, sd headers, 3.4", zzp 1.0 230K miles scrapped.
    04 Comp G zzp stb's, UMI ta's, Speedbuilt sways, bully flo heads, XP, zzp headers, fsic, thrasher shift kit, 60#, 2.6" corsa 2.5", Inferno hood
    01 gt z7 turbo tep trans zzp motor
    08 g8 gt cam exhaust 11.87@118
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  20. #20 Re: false kr where is it comeing from 
    GT Level Member jrb1027's Avatar
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    I might do that sometime if youll take me for a ride in your car lol ill pm you my number
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