[Bandi]

For some time my NPP has not been working. I've had the rattle for a while but trying to change modes simply doesn't work anymore.


I just tried checking the fuse to see if it was blown and tested it on a multimeter and it's fine. The connections on the actuators themselves are connected and fine. I don't think the flaps are stuck as when I try to change exhaust modes, they don't sound like they even try to cycle. I feel like I would hear at least an attempt by the valves to move after changing modes.

I've also tried disconnecting the battery entirely and reconnecting, that also didn't work.

I know going to a dealership for a relearn is an option, but my concern is that they'll try to reflash and I am tuned with bolt-ons. Is this a concern I should have, or should I be fine if I really wanted to get the problem resolved?

[Rock-It Man]

I would suspect your tune.

[LT4Greg]

Second that. Probably have to get with the tuner as I don’t think a dealer will touch your car since it’s been tuned.

[Bandi]

Understood, thank you for the replies

I may just accept it for what it is and go with an aftermarket muffler with no valves

[Mark114]

Originally Posted by Bandi

I may just accept it for what it is and go with an aftermarket muffler with no valves

Are the valves stuck open or closed? If they’re stuck open then you essentially have a muffler with no valves. If they’re stuck closed, do they open when running with the fuse pulled?

[Bandi]

Originally Posted by Mark114

Are the valves stuck open or closed? If they’re stuck open then you essentially have a muffler with no valves. If they’re stuck closed, do they open when running with the fuse pulled?

They are stuck open. I’ve tried pulling the fuse to “reset” it but it did nothing. Changing modes does nothing. The fuse is fine.

I originally thought that since I stuck them in Track for so long they just got stuck from the soot in the exhaust going through so many heat cycles that they just binded themselves in the open position, but they don’t even try to move. I should hear resistance or something when trying to open them I feel like but I hear nothing.

[Dynamical]

The hot exhaust gasses probably screws the damper up. You said it’s rattling? Probably burned something in the damper loose. Gasses make it rattle.

IMO this is the kind of stuff I like to do without. When I get my car it will have no npp or it’s coming off and a good old fashioned aftermarket system will be going on. **** all that new cute shit just my opinion

[Kerry]

U can move the v4 valves to the back valves. Their are a total of 4 valves. I had one fail and did that but both at the same time is strange. they are spring loaded and the natural position is open.

The valve closed requires the servo to close the valve and hold it. Release power and it will open, because of the spring.

[Kerry]

btw the part of the tune that controls the valves is completely separate from the engine and trans. I dont see any way that the tune is corrupt causing this. The ,i think fuse 51, would do it for sure

[Mark114]

The rattling is a known problem with the NPP exhaust. I posted some possible solutions below. You can easily remove the actuators from your NPP valves to check them for damage or binding. I suspect that the previous posts to your thread are correct that it is an issue with the tune. Putting the car into Snow/Ice mode should close the valves. You could try that to see what happens.

There is a TSB with one solution:

https://static.nhtsa.gov/odi/tsbs/20...82403-5448.pdf

There is a second solution here:

https://www.camaro6.com/forums/showthread.php?t=556061

[RobZL1]

Originally Posted by Kerry

btw the part of the tune that controls the valves is completely separate from the engine and trans. I dont see any way that the tune is corrupt causing this. The ,i think fuse 51, would do it for sure

I don't think we're saying the tune is corrupt, just that the BCM might be tuned to hold the valves open in all modes/conditions.

Also, none of the ZL1's have DOD valves, for what it's worth.

[Kerry]

Originally Posted by RobZL1

I don't think we're saying the tune is corrupt, just that the BCM might be tuned to hold the valves open in all modes/conditions.

Also, none of the ZL1's have DOD valves, for what it's worth.

did not know that o well