My friends car started to have inconsistent random knock.
Sometimes 0 knocks, sometimes little 5 knocks, sometimes max 36 counts. We checked everything what we can imagine...
And found the problem - loosen knock sensor from the block. It was inside, but can go out with fingers.

 

Interesting. added to the list of many things it could be.

 

Make sure to tighten to OEM torque specs or you'll make it to sensitive. Also visually check the condition of the knock sensor. They are only like $60 or so, so if it looks beat up or the shielding is chafed just replace it.

Its usually hard to get a torque wrench back their and it is a huge socket with a wire coming off it. My best advise is to practice outside the car with a torque wrench to the proper setting and get a feel for it with your hands. Then reach behind the block and do it with a regular open ended wrench.

 

hmm, i have the same issue. This may explain it, im gunna have to check it out. thanks.

 

The sensor's are torqued to the block to pick-up the knock correctly. They probably do so on the cautious side which might explain the crap we have to go through. However, loosening it might mess it all up

 

interesting!

 

Good info, thanks for sharing

 

I think we need a sticky with possible sources of phantom knock.

 

So if it's too tight, then it could cause it to pickup noise that it wouldn't normally register ?

Or are you saying if it isn't tight enough, then it might cause it to pickup more noise ?

 

Yes. As I understand it, it could be both.

 

So it has to be precisely torqued ey? I need to figure out my problem...

So are you saying you made it finger tight and fixed the issue? I don't understand exactly.

Spec is 17ft-lb +/- 1ft-lb

 

That socket looks a lot like the generic sensor socket you can get at Autozone. It has the slit on the side but its stepped with two different socket sizes on the inside. It'd be feasible to get the smaller in.lb. torque wrench back there and torque it to 204 in.lbs.

 

Crowsfoot FTW!!! Seems like this could be a simple source that many of us could check pretty cheaply. Thanks for the info.

Josh

 

Okay, I PMed Darwinn to clarify:

Quote:
Originally Posted by honki24
I'm trying to figure out exactly what the issue was with the knock sensor in the car you guys "fixed". Was it loose? Was it too tight? How did you fix it? Did you just make it finger-tight or did you torque it back down to 17 ft-lb?

"Knock sensor loosen from the block, maybe it come free from vibration or something, I dont know exactly.
Its very hard to get to knock sensor, by I personally done this with my hand - tried to turn it, and it was LOOSE(free) but insinde hole. ( Not torqued at all ).
This given phantom knock everywhere, but more upto 4000rpm. At WOT runs 95% of time we had 0 knocks.

We choose to use "Lactite". So got it out from the block, used some lactite on thread and torqued it back with stock specs.

No any problem for now. No any false knock."