silver2013

2013 grand sport,took fuse out exhaust still wont open at 3500 rpm. engine off normal (open).start engine they close(normal). thanks for any help.

nuke61

Double check that you have the correct fuse. Another alternative is to remove the vacuum hoses from the valves.

SweetZO6

Any engine codes? Don't know for a fact but some codes probably will not let exhaust open.

Ed

psp6158

You have a vacuum leak obviously, try to see if the hose is still connected to the back of the intake, very hard to see. Some of us had the plastic bend crack where it goes into the firewall. There is a solenoid behind the passengers side tail lights that also goes bad. Those are the most common although the hose on the back.of the intake seems to only occur if the intake was recently off.

nuke61

Why do you think the OP has a vacuum leak? He said that it closes when the motor is running, and it's open when the motor is off, so the vacuum is working to close the butterfly valves, right?

LMB-Z

My guess would be the vacuum switch behind the tail lights has gone bad. Its behind the passenger side tail lights.

silver2013

i just noticed the fuse for exhaust was blown replaced it blown again

silver2013

what would clause this.

Buddy A

Try unplugging the electrical connection at the solenoid behind tail light. Replace fuse and see if it fails. My guess is the solenoid is bad.

nuke61

silver2013, from your original post you said:

• when the motor is NOT running, the NPP valves are Open
• when the motor IS running, the NPP valves are Closed

Your issue is that when >3500 rpm, the valves should Open, but they don't, is that right?

If you took out the correct fuse, or if it blew, those valves should just stay open.

Buddy A

When my solenoid went out my symptoms were strange to me. Upon start up my exhaust worked normally. Valves either open or closed dependent on where I left the mild to wild set. They would be normal until I either opened the valves by the switch or RPM. At that point they would not close. Turn off car and when I started it it would again start to work normally. Until they opened as they should.

jft69z

We changed the solenoid today, all fixed.

Joe T.

psp6158

Thanks for coming back and giving us the update, it's nice (unfortunate) there are some common issues on these cars that we can now troubleshoot ourselves they are so common.

jft69z

It failed in the 'valves closed' position. Valves open when car off, fully closed when running (engine vacuum applied), blown fuse due to internal short.

No outward signs the valve was damaged or melted as some have experienced.