strange harmonic or resonating sound
 

hello all I have a strange harmonic or resonating sound coming from the
passenger side of car 2500 to 3000 rpm range...all heat shield are good
any ideas?? 87 300zx 2+2
:confused:

All the gremlins are having choir practice. ;^>

Seriously, something is loose and vibrating. Just start banging on stuff until you hear it. Things like heat sheilds can appear (and actually be) tight, but, at just the right engine speed, will start buzzing and making a fuss. Could be something loose in the door, the glove box, etc., etc.

I did all that still there..could the exhaust system be bad? or the cat...
 

I did all that still there..could the exhaust system be bad? or the cat...

well??? is there anyone else out there??????
 

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Have you been under the car? There are other heat shields, under the car, that are known to buzz and viberate.

You will also need to get under the car to inspect the exhaust system. If you have an exhaust leak, under the car, you should see an area at the leak that has a black, carbon stain.

If the car runs okay, and you can detect exhaust flow (engine running) at the tail-pipe, chances are the cat is okay. The only thing that usually goes wrong with a cat is it will clog. Running too rich, or, too much oil blow-by will clog the cat.

You may have to get down (under the car) and dirty to figure this one out. :p

I have been under and checked all you have mentioned..checking the mounts next..
 

I have been under and checked all you have mentioned..checking the mounts next..