Does knock sensor pickup rod knock noise ?

[Lurker]

I can hear a muffled knocking sound from my car whenever the rpm goes around 3K rpm.
I did a search, and seems like rod knock noise is most pronounced around this rpm range.

However, my knock sensor does not show any activity. Does knock sensor usually pick up noise created by rod knock ? Since the knock sensor does not register anything, does that mean the noise is probably not rod knock, and just probably something loose and resonating ?

It's difficult to pin point the noise. I tried revving at idle, and I can hear it if I'm in the car with the hood closed. But, if I'm outside the car with the hood open, and revving the engine manually on the throttle body, I can't hear anything, because the engine is loud.

What do you guys think ? No knock sensor activity means that it's not rod knock ?

 

[Doug99RS]

While a rod knock will have slight movement in it outside of a normal condition, I doubt very seriously that the crank sensor is useful in distinguishing a rod knock from engine knock. You might have rod bearing wear. I suggest draining the oil in to a clean catch can and checking it for metal flakes or shavings.
Doug

 

[Lurker]

Originally posted by Doug99RS
While a rod knock will have slight movement in it outside of a normal condition, I doubt very seriously that the crank sensor is useful in distinguishing a rod knock from engine knock.

Thanks for the advice. I'll go drain the oil and check for flakes.
However, do you really mean the crank sensor ? I was asking about the knock sensor.

 

[Doug99RS]

No, it was a long day and I wasn't thinking straight. I did mean the Knock sensor like you had asked about. Sorry.
Doug

 

[Lurker]

BTW, I drained the oil, cut open the oil filter, and no metal shavings was found.

I guess it's just some loose parts that are resonating at a certain rpm range.

 

[Defiant]

Check the harmonic balancer.

 

[Lurker]

Don't you hate it when you do a search to figure out your problem, then you saw a bunch of threads that has no conclusion. Well, this one is not going to be one.

I figured out what the noise is.. It was the stupid O2 housing heat shield. I jacked up the car and tap around with my wrench. I found that one of the bolt was loose. Tightened it, and the noise has gone away.

Strange that when I'm driving around it would sound like it's coming from the driver side, not from the engine bay at all.
I guess it's quite difficult to pinpoint noise while you're driving, probably because of the sound being reflected all over the place..

Hmm.. now if I can get my drivetrain-slack fixed, my car would be free of mystery noises

-Luke

 

[Doug99RS]

Thanks for the update Luke. Nice to see someone putting bringing some conclusion to a thread. Working on cars professionally, I fully understand the confusion that you dealt with when hunting down a noise. Good find.
Doug