[rootus]

Noticed a new sound last night. Driving about 70 mph or so, sixth gear, rolled onto the throttle a bit when switching lanes and got a very distinct rattle that sounded like it was coming from my right. Didn't really sound like it was behind me, but whatever. Reproduced it reliably several times, and found that if I kept pushing down on the throttle it would go away at higher throttle positions.

I'm running the exhaust in track mode, so it's open most of the time but I think it closes at cruise in higher gears at lower throttle positions, yes? Is what I'm hearing probably just the 'infamous' NPP rattle?

[Spartan268]

Most likely it. Just do a cold start next morning and listen in stealth mode. You'll hear it in an instant.

[R3ctivision]

Definitely the NPP rattle. Even in track exhaust mode, in 6th gear light throttle the valves still close to prevent droning on the freeway. If you apply more throttle to accelerate you'll hear a loud rattle from the back of the car (mine is also on the right side). If you accelerate hard enough or downshift, the rattle will go away because the valve will open up.

[speedup]

Does the chevy dealer "fix" with epoxy work?

[nasbagoat]

if it doesn't then you get a new exhaust.... so win win....

[biker2k]

how common is this problem?

[TrackClub]

Originally Posted by biker2k

how common is this problem?

I had it. Drove me nuts. Took it to my dealer. They had a bulletin on it but we were both sceptical as to its ability to resolve the issue. So we opted out for an easy fix: pull the fuse. No more rattle. No drone issues either with baffles open all the time.

[bullet3z]

Originally Posted by TrackClub

I had it. Drove me nuts. Took it to my dealer. They had a bulletin on it but we were both sceptical as to its ability to resolve the issue. So we opted out for an easy fix: pull the fuse. No more rattle. No drone issues either with baffles open all the time.

Sorry to ask this.

What fuse did you pull? Also by pulling the fuse do you lose the stealth mode? I would assume that by pulling the fuse, you no longer have the use of the NPP system?

Again, sorry to ask. I see this tern come up and I never really understood it completely. I thought is was something that was done to the 5th gens and the older Vetts.

[TrackClub]

Originally Posted by bullet3z

Sorry to ask this.

What fuse did you pull? Also by pulling the fuse do you lose the stealth mode? I would assume that by pulling the fuse, you no longer have the use of the NPP system?

Again, sorry to ask. I see this tern come up and I never really understood it completely. I thought is was something that was done to the 5th gens and the older Vetts.

I knew this question would come up lol! I think it was #26 but I don't remember and am far away from my car right now. There is a fuse map in the manual I think. Or a dealer could help. And yes she stays loud but really unless you go WOT it is not bad at all for regular DD duty.
I don't miss other set ups at all.

[mjk3888]

Originally Posted by speedup

Does the chevy dealer "fix" with epoxy work?

only for about a month then it returns. Ask me how I know. I also did the fix myself to insure it was done properly and it still returned.

[speedup]

Originally Posted by mjk3888

only for about a month then it returns. Ask me how I know. I also did the fix myself to insure it was done properly and it still returned.

Did they replace the exhaust?

[mjk3888]

Originally Posted by speedup

Did they replace the exhaust?

Nope just the epoxy fix.

[Ironhide]

Almost certainly the NPP rattle. My dealer warranty-replaced the entire exhaust... it's better but still does it, especially in touring mode. Just sucks.

[TrackClub]

Just pull the fuse and it is 100% fixed. I know it will be louder but then again it is a sports car...