[acannell]

anyone running a 2.5 or 2.2 8V engine and actually witnessed and confirmed false knock at higher than stock boost levels?

i presume the only way this could happen is if your cal blinks the check engine light on knock or you have an OTC 2000 and saw it indicate knock, and then somehow you investigated and confirmed there was no actual knock.

just looking for some real-world proof that this actually happens

 

[xrattiracer]

i know its slightly unrelated, but i witnessed it on my 2.3 ford with dodge smec electronics. the computer pulled back timing so far that my exhaust manifold was glowing red by the time i made it a few blocks. after that i unhooked it and havent ran one since.

 

[ATaylorRacing]

One of the dealership mechanics showed me how sensitive the knock sensor can be....I explained that when I would drop the clutch when drag racing it would take off strong or weak...not consistant. He gave a good tap to the intake and the timing was retarding.thinking it was spark knock....he took out the sensor and I never had troubles again...he said if you use a lot of thread sealant on that it takes away some of the sensitivity.

 

[jrbisig]

A knock sensor is a (spelling may be off) piezolectric device, which means the metal produces a a/c voltage when vibrated. You have to relize that back in 1987 the electronics where not all that fast. By the time the computer saw knock, then corrected it, it pulled the performance way down. In todays computers, the computer can watch knock so fast that it doesnt pull timing untill it reaches damaging levels(oem determind levels). It wouldnt suprise me to see a ac compressor clutch cycling on/off on a older car fool the computer into seeing knock. False knock can be anything that causes a vibration somewhat close to the sensor. Bad engine bearings, bad alternator bushings, loose flexplate/torque converter bolts.
james

 

[BAKES]

2 years ago i had noisey lifter set my knock sensor off ,i chase for week before finding it

 

[ATaylorRacing]

A knock sensor is a (spelling may be off) piezolectric .......It wouldnt suprise me to see a ac compressor clutch cycling on/off on a older car fool the computer into seeing knock. False knock can be anything that causes a vibration somewhat close to the sensor. Bad engine bearings, bad alternator bushings, loose flexplate/torque converter bolts.
james

Or a hard launch at the drag strip as was my case.

 

[speeduphoria]

I have yet to get my SDS standalone to be able to use the knock sensor w/o getting false knock, using stock sensor. I have a sensitivity adjustment and rpm cutoff and still get false knock. I will be trying some teflon tape on it and try again, but lately I just have it set so it doesn't pull timing.

 

[Sittn86]

Accrding to the Readme that comes with the CHeM program, an overtightened sensor can cause false knock.

 

[speeduphoria]

Accrding to the Readme that comes with the CHeM program, an overtightened sensor can cause false knock.

thats what I told him in another thread, there IS a torque spec for the knock sensor

 

[Sittn86]

thats what I told him in another thread, there IS a torque spec for the knock sensor

Yes, I think in that thread I posted "turn it until it stops, then turn it 1/4 turn," or something like that. Having since downloaded CheM & read the Readme, I realized I was wrong & I apologize for the misinformation.