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I have the NPP exhaust on my 2013 Grand Sport and lately it has been changing modes by itself even when just tooling around town?? It works fine with the Mild to Wild remote and operates fine under heavy acceleration as it is designed to do. What could be the cause of it just opening on its own from time to time? I know it is controlled by a vacuum system, is there a problem with the vacuum?
Is this a fix I can handle at home or is it a dealer issue?
Thanks for the help as I am sure I am not the first guy to experience this issue!!
Suggest you remove as many variables as possible, starting with the M2W switch. Put the fuse back. If the problem goes away, then be suspicious of the M2W system, and you can start troubleshooting that. Could be the fob, could be the connector plugged into the fuse box, the wiring going to the controller, the controller itself. If the problem persists, then the problem is with the car; vacuum leak, vacuum switch, etc. The rest of it is beyond my pay grade
I had a similar issue with my NPP and Mild to Wild. It would stay open(noise) while accelerating over 3400 rpms, and wouldn't close after the rpms dropped, even though the MTW was set to on(no noise).
In the morning starting the car with the MTW on(quiet), it would open and not close until I drove for a couple of miles. It finally failed 100% to noise all the time.
I pulled the MTW plug, and put the 10amp fuse back in. Same results. I took it to the dealer, and it turned out to be the exhaust vacuum solenoid located behind the 2 passenger rear taillights. It seems to be a common problem with this part.
Last edited by marinablu67; Jan 12, 2020 at 08:28 AM.
I recently had a similar issue. System worked fine as designed in factory mode. With MTW switch it would not operate at all. I replaced the MTW remote battery with no effect. Turned out the stereo installer removed the ground to the MTW switch. Fixed ground, fixed problem. The MTW also has a fuse you should check.
So I think you have a solenoid going bad in the rear, a vacuum leak, or possibly an intermittent ground problem. By the way, if you find out the MTW switch is going bad, the same exact 12V remote switch can be purchased on Amazon for about $15 ad it comes with new remotes.
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NPP Exhaust Issue
