Good evening,

I have an '06 5AT G35 coupe, with 54K miles, and I started hearing this noise when I'm accelerating relatively hard. I thought it was the heat shield but I put it on a lift and nothing is loose..
It happens at around 2-3k RPM in 1st, 2nd and 3rd gear, and it happens mainly in drive, but when I'm in manual mode it won't happen unless I really step on it.

Can anyone throw out a few ideas?

Thanks in advance.

 

do you have a pet rattlesnake

 

My 06 5AT had a short rattle at high RPM's and it ended up being something with the cat. It was replaced under warranty.

 

If it's not "detonation" from bad gas/timing, then you most likely have a heat shield loose.

 

check your cats . I had the same problem and that's what it was

 

cats or knock

 

Like said. most likely some component in the exhaust system. nothing may seem loose to the eye, but even if the head shields are tight, the baffling/material in the cats/resonators/mufflers/flex-pipes can wear out and come loose and start to make noise as well.

 

Agree, had the same problem and ended being a bad cat. Got it replaced under emission warranty. If you want to make sure take it to a muffler shop and they will tell you if it is a loose component from the exhaust.