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The false knock shell game.

bluebeastsrt

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Well for the first time in 5 years. I’m about to play the false knock shell game. Looks like I’ll be laying under the car this weekend tightening every damn bolt I can find. I recently had a sai Li fuel system installed. Lund is doing the tuning. They informed me the car looks great on a 3rd gear pull. From 3000 to 6500rpms. But once we went to a 40 roll thru the gears. Knock reared it’s ugly head on ever shift! My money is on the headers. They were installed in 2015 and haven’t seen a wrench since the install. I’m also thinking it might be the fuel line that was left in place during the install. So many wonderful options to choice from.
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gimmie11s

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You are seeing positive knock count in he logs? What fuel are you tuning with?
 

Vegas5OH

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What type of boost do you have, my car started knocking nasty turned out to be bad belt slip. Dont know if you recently put a smaller pulley on it
 
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bluebeastsrt

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You are seeing positive knock count in he logs? What fuel are you tuning with?
We’re tuning on E85. The knock only happens on the shifts.
 
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bluebeastsrt

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What type of boost do you have, my car started knocking nasty turned out to be bad belt slip. Dont know if you recently put a smaller pulley on it
No been running the 3.6 pulley from the start. It’s a Paxton 2200. Everything was fine when the car was dyno tuned last summer. Dakota from Lund has told me its highly unlikely we’d get knock on e85. And it’s only happening when the car shifts. He explained that if it was tune or fuel related. It would show up on the single gear pulls also. But that’s the beauty of trying to find it. Soooo many things to check.
 

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I had the same issue, went with solid motor mounts and the issue went away. Not saying it will fix your issue but I went bolt by bolt, and never found anything. I figured something during the shift was making noise that pissed off the knock sensor and that was somehow related to movement of the motor. $100 and an hour later I had the BMR mounts in and problem was gone. Lowered the motor by 1/4” while is was at it too.

Good luck! It’s sucks ;)
 
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bluebeastsrt

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I had the same issue, went with solid motor mounts and the issue went away. Not saying it will fix your issue but I went bolt by bolt, and never found anything. I figured something during the shift was making noise that pissed off the knock sensor and that was somehow related to movement of the motor. $100 and an hour later I had the BMR mounts in and problem was gone. Lowered the motor by 1/4” while is was at it too.

Good luck! It’s sucks ;)
Lund mentioned to check the motor and transmission mounts while looking. So thanks for the heads up.
 

Tommy V

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Hey man something to look for, does it add the timing right back after the shift.Mine car did that all the time.Would pull almost all the timing out on a couple of the shifts.Could be two things,Either something hitting making noise when shifting or hitting a torque limit at the shifts.I did not want to desensatize the knock sensors anymore then they were so i just left my alone.If its not adding timing right back.after shift you have to find out why.Also make sure you have advance trac off while you are doing your logs,that could cause knock if it spins at the shift.U can also look at rpm and mph to see if its spinning at the shift,my car does this alot on the street.
 

Boduke0220

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Seen headers hit a million times!
 
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bluebeastsrt

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Hey man something to look for, does it add the timing right back after the shift.Mine car did that all the time.Would pull almost all the timing out on a couple of the shifts.Could be two things,Either something hitting making noise when shifting or hitting a torque limit at the shifts.I did not want to desensatize the knock sensors anymore then they were so i just left my alone.If its not adding timing right back.after shift you have to find out why.Also make sure you have advance trac off while you are doing your logs,that could cause knock if it spins at the shift.U can also look at rpm and mph to see if its spinning at the shift,my car does this alot on the street.
Per Dakota it will spike up to 5 or 6 on the shift. And starts adding again after each shift. In a stair case pattern. He's seams positive its not real. So I'm going with the real obvious stuff first. I need to look over The Sai Li install. See if a portion of the old fuel line is moving around? As we didn't have this issue til after the install. Or my next bet is the headers. Thanks for the Tip on the advance trac.
 
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Per Dakota it will spike up to 5 or 6 on the shift. And starts adding again after each shift. In a stair case pattern. He's seams positive its not real. So I'm going with the real obvious stuff first. I need to look over The Sai Li install. See if a portion of the old fuel line is moving around? As we didn't have this issue til after the install. Or my next bet is the headers. Thanks for the Tip on the advance trac.
Yours seems exactly like mine. Same tuner (and person tuning) only difference is I went Fore instead of Sai Li. I know Sai doesn't use metal lines but check for line tap just in case. Also, check for any brackets you may have modified. My guess still is the motor movement is somehow translating to knock... It could be the softer bushings and the extra whp exposed the soft point and the shifting is causing the knock. Again, good luck and let us know what ends up solving the issue.
 

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Per Dakota it will spike up to 5 or 6 on the shift. And starts adding again after each shift. In a stair case pattern. He's seams positive its not real. So I'm going with the real obvious stuff first. I need to look over The Sai Li install. See if a portion of the old fuel line is moving around? As we didn't have this issue til after the install. Or my next bet is the headers. Thanks for the Tip on the advance trac.
No problem,if not turned off it will pull.timing.Also if i were u i would look at mph and rpm on your log right at the shift.If you see the mph jump up at the shift it is spinning.This happens alot with how hard these transmissions shift and especially on the street.If you do see it spinning it will pull timing and really is not a problem.
 

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Along with the fuel system and headers, also check the exhaust tips for hitting on the rear valance. Check all the intake piping/BOV/etc, If you're auto check the plate between motor/trans.

A great tip I learned was use a rubber mallet and bang on the exhaust in different spots while listening for a metallic rattle. Most of the time false knock is caused by something touching the exhaust or motor not usually something touching the body, but it's not impossible.
 
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bluebeastsrt

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All good stuff to check. Im compiling a list. Problem is the list is long as f$&k already.:frown:
 
 




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