107

I have asked about this before, but still haven't solved it and it is REALLY annoying.

The symptoms are as follows:
I get a very strange vibration/rattling sound that is similar to the sound you get when you let the car creep forward on brakes- it only appeared after my header install. Someone suggested the headers/exhaust might be hitting somewhere, which would sound right, but I have looked everywhere, including while the sound is happening, and can't see anywhere without plenty of clearance.

It happens under light acceleration(from slow or a stop up to about 15mph) and braking(also only below 15mph). It ONLY happens while the car is in Drive, not in N or R. It is most noticeable when the car is stopped and the brake is applied- let off the brake and the noise will stop. Engage the E-brake, let off the brake, and the noise will stop. Keep the foot on the brake, and shift the car into N or R and the noise will stop.

It is NOT audible from outside or underneath the car, even with my head under the car or under the hood- only from the inside. From there it sounds like its coming from the front+center and underneath but I can't be sure.

Could it be the tranny for some reason? I am 99% sure it is not my engine mounts(I have revved the engine while the car is in drive with the brake on, and don't see or hear anything hitting from outside) but may end up changing those if I dont get any more ideas because I am all out.

Please help me!

camaronutt

I have a similar noise on mine. If I'm in 2nd pulling out and the rpms are low it has a noise. I'm pretty sure its my exhaust, or a heat sheild or something of that nature. Hope you find it, rattles suck, especially when they hide from you.

107

Alright, damn it, I was 99% sure but you shouldn't have bet on me... Turns out the header was indeed hitting, passenger side on the suspension cross-member(above where the A-Arm bolts in). It was really hard to spot and I only saw it when my car was up on a lift at the GM stealership. When I got home I put a jack under the collector and jacked it up as far as I could(~2") and this created what looks like an extra 2mm of clearance(not much). If that doesnt help, I think I will be changing motor mounts. The dealer swore they weren't sagging but I trust your guys' experience over the dealer any day...