[ap1969]

I have a 2017 Camaro SS. It has 77,000 miles on it. I purchased it when it had 75,000. I noticed when I first got it if I was accelerating hard when it shifted it was like a rattle noise. Of course, right away I thought it was that torque converter chatter. The man who bought it new, had the transmission fluid flushed at 25,000 miles because of that and I had it changed flushed as soon as I bought it. There is no lack of power no slipping, shift solid,so I don’t think that’s what it is also, that should eliminate the cats. Great power runs very smooth. Now lately it’s been doing it a little bit more always under acceleration and not easy acceleration, but punch acceleration. It sounds like a pipe or something rattling. Unfortunately I can’t pinpoint it because it doesn’t do it all the time. Any ideas? I read on here that it could be a busted muffler, bracket or that shielding. That is what it sounds like but I don’t know where to look for that other than putting it on a rack. does anybody have any ideas thank you very much

[beowulf556]

Do you have NPP exhaust? The valves are known to rattle.

[ap1969]

Originally Posted by beowulf556

Do you have NPP exhaust? The valves are known to rattle.

The engine valves? Do you mean the different modes? Yes.

[ap1969]

Higher rpm and more in sport mode?

[beowulf556]

The exhaust valves on the muffler. Do you have 4 tips?

[SomeGeoffGuy]

Sounds like spark knock. Does it sound like marbles rattling around in a tin can? Are you running premium?

-Geoff