Okay I lied a little. I have read many other posts on here regarding various rattles, but none of them mention if the rattle is only when car is in D. I can't reproduce this rattle when depressing the accelerator in P. Does the fact it doesn't rattle in P eliminate it being a potential cat issue, or timing chain tensioner? I was sure it was a loose heat shield. Very tinny sound at low RPM, but I had a shop weld up anything they thought might be causing the rattle, and it's still there. The car in question is a 06 G35x. Thoughts? And thank you in advance.

 

Get it up on a lift and reproduce the issue while someone finds the rattle, these things can be really annoying to troubleshoot on your own. If you can get us a youtube video of the sound in question that will help.

A mechanic stethoscope with a long probe is your friend!

 

Check the driveline system?

 

I have attached some audio. What you're hearing here is depressing of the accelerator, which in itself makes no rattle while it is held down. It's only when I let off the pedal the rattle is produced. I said in my previous post I couldn't reproduce the sound in Park. What I meant was in park it only makes the sound when I let off the pedal, whereas in Drive it will make this noise at the blip of the throttle.


The photos were just something to accompany the audio. Somebody cracked my bumper. This was my amateur repair. Turned out respectably enough.

 

That sounds like exhaust rattle to me, look under it for a broken hanger, OR a worn motor mount, if you blip the throttle does the engine torque to the side in the engine bay?

 

I also thought it was exhaust rattle, but the shop welded up any potential loose areas - unless it's something internal within the exhaust. I don't think a motor mount would produce this particular sound.

 

Not the motor mount directly, but if the engine can move enough then all sorts of stuff has the potential to vibrate, various hoses against body/chassis and stuff like that. See if you can narrow it down with a mechanics stethoscope and a buddy playing with the throttle to reproduce the noise.