I have a 2002 AP1 with a strange sound coming from the underside at low rpms.
At first I thought it was the old rusty brakes scraping against the rotors, but realized it happens while stationary. I've been doing research and can't find anyone with this type of sound. Definitely not the TCT, possibly the clutch? but all the clutch buzz videos sound different and are usually occurring at deceleration. Watch the video below, it gives a good quality hear at the metallic rattle/scrape. Any information will be helpful and appreciated!!

btw it has been happening since I bought the car 9 months ago, no effect on performance. Rattle goes away once I get above 20mph.

 

I would start by checking the heat shields on the header and CAT, could really be anything that is not tight but should be. Good luck.

 

If you can get it up in the air a bit and listen around the general area with a directional tube of some kind - I often use the tube from paper towels - you might be able to narrow down the area and then identify the source of the noise.

 

Thank you for the speedy replies! I'll get it in the air and respond back when I figure it out.

just glad it doesn't sound like a tranny problem to you guys

 

To be clear - I have no idea what it is. But, you will soon find out.

 

Sounds like a loose or cracked bracket of sorts somewhere. Could be the cat but that is closer to the passenger side so should be easier to discern if that's the side the noise is most prominent.

 

Mine makes the same sound, also a 2002. I figured its loose a heat shield or something like that. Haven't gotten around to fixing it, not noticeable with road noise and it also seems to not happen when the car is hot.

Never happened before I had a clutch job late last year, which IIRC involves removing the cat and some of the exhaust work to drop the engine and transmission.

 

Okay, so it is the CAT making that prominent metallic sound. Unfortunately it doesn't have a heat shield and is rattling from the inside. I decided to go ahead and order a magnaflow S2000 fit off eBay for $320.

It was my first time under and there was a whole mess of front fender plastics unbolted and hanging low. I'm sure this doesn't help the sound quality lol so I'll finish them up tomorrow.

Here is a picture of the current CAT:

 

Thats not a cat, its a resonated test pipe. and the baffle in those will fall apart eventually and rattle around. I had the same one that did the same thing to me. The solution for me was getting a another TP without the resonator. $80/ but wile waiting for it to arrive, i took a hammer to the outside to "crimp" the baffle tight inside and shut it up, without effecting the inner flow. Picture a bunch of steel wool wrapped around a perforated center pipe in the raised portion. I effectively got rid of the raised section with my hammer lol

 

I figured it was a Test Pipe judging its size, but didn't want to assume anything. Im going to stick with my HFCAT purchase. Not to be on a high horse because caring about the environment is nice, but mainly because I dont want any BS from the DMV or police

I appreciate all the helpful info friends!