NPP Wide Open?
Thread Starter
Heel & Toe
Joined: Jan 2017
Posts: 23
Likes: 3
From: Seminole Florida
NPP Wide Open?
I have a 2013 GS with 17k miles. The other day while out the exhaust volume went to the extreme. I assumed the baffle was stuck open and when I got home I found my assumption was correct. Looking over this great site I see where it probably is caused by one of 2 things, either the fuse or the solenoid or perhaps both. I found great info on how to check and fix, however my question is would there be any harm if I just left it as is? I have not checked either one as yet due to time but was wondering if whatever caused the issue could it hurt something else?
Thanks in advance.
Thanks in advance.
Le Mans Master
Joined: Jan 2017
Posts: 6,134
Likes: 1,962
From: Morris County New Jersey
Most guys I know, purchased the Mild to Wild switch. Then you can go from quiet to load at the push of a button whenever the urge hits you. I leave mine in the open (loud) position 98% of the time.
Racer
Joined: Apr 2018
Posts: 250
Likes: 20
From: Pensacola FL
I have a similar problem, mine will not close after start sometimes, other times they operate as they should. It takes electrical power to close them and the fuse has to be good if they close when they feel like it. Local Corvette shop shop guru says it's carbon build up and I need to quit driving it like a pu**y and stand on it, get the revs up. He said to burn it off I need to put it in park and floor it to the red line, heat it up. Not sure I want to do that.
Safety Car
Joined: Dec 2007
Posts: 4,974
Likes: 148
From: Magnolia Texas
Running open will do you no harm. Would double check it is the fuse since other cause could be a vacuum problem and that might impact performance. Believe vacuum leak would cause baffles to fail in closed position but I’d check the system just to be sure. Change the fuse and see if the exhaust acts as designed.
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Melting Slicks
Joined: Jan 2017
Posts: 2,706
Likes: 897
From: CONCORD CA.
the previous owner or broker, had switched the fuse already. I've been wide open for almost two years.
no intention of going "stealth". my last car ('98 Z28), had headers with 3" collectors. after the cat's, they were wye'd into
a single 4" exhaust out back. it had a decent idle sound, but when you got on it, it would put the open NPP to shame.
this was my dad's car and, was his set-up. he drove the hell of out this car.
no intention of going "stealth". my last car ('98 Z28), had headers with 3" collectors. after the cat's, they were wye'd into
a single 4" exhaust out back. it had a decent idle sound, but when you got on it, it would put the open NPP to shame.
this was my dad's car and, was his set-up. he drove the hell of out this car.
Race Director
Joined: Dec 2013
Posts: 12,502
Likes: 3,629
The fuse in the passenger well, controls the NPP controller, which controls the vacuum solenoid.
With now fuse, the NPP and the Vacuum solenoid do not get power up, and since the normal non powered state of the vacuum solenoid does not vacuum through it, the muffler gates stay wide open. When the controller does have power to it, it powers up the solenoid to allow vacuum through it , and this closes the muffler gates.
When the RPS reach high enough, and you are deep into the throttle pedal, then the NPP cuts to the power to the vacuum solenoid, and this allows the gates to open as long as such demands are meet.
So yes, the gates are controlled by the vacuum off the intake manifold, but you have electronic items controlling the vacuum as well.
Go post #8 to see all the parts that make up the NPP system.
https://www.corvetteforum.com/forums...tuck-open.html
With now fuse, the NPP and the Vacuum solenoid do not get power up, and since the normal non powered state of the vacuum solenoid does not vacuum through it, the muffler gates stay wide open. When the controller does have power to it, it powers up the solenoid to allow vacuum through it , and this closes the muffler gates.
When the RPS reach high enough, and you are deep into the throttle pedal, then the NPP cuts to the power to the vacuum solenoid, and this allows the gates to open as long as such demands are meet.
So yes, the gates are controlled by the vacuum off the intake manifold, but you have electronic items controlling the vacuum as well.
Go post #8 to see all the parts that make up the NPP system.
https://www.corvetteforum.com/forums...tuck-open.html
Last edited by Dano523; Oct 17, 2018 at 12:44 AM.
Le Mans Master
Joined: Jun 2008
Posts: 8,233
Likes: 411
From: Mt. Sinai NY
I have a similar problem, mine will not close after start sometimes, other times they operate as they should. It takes electrical power to close them and the fuse has to be good if they close when they feel like it. Local Corvette shop shop guru says it's carbon build up and I need to quit driving it like a pu**y and stand on it, get the revs up. He said to burn it off I need to put it in park and floor it to the red line, heat it up. Not sure I want to do that.
Clif
Heel & Toe
Joined: Aug 2018
Posts: 16
Likes: 0
Help please
Help please
I put it in 1st and had already taken my foot off the clutch and started rolling, everything's normal right. Then I step on the gas and "snap", I freak out, I dont know what happened. I stopped the car and tried driving again, I release the clutch very slowly until I start moving and I give gas and it just wont go, the clutch is slipping I think. I wait about 5 minutes, I try again, it is still slipping but I get the car moving, barely, I drove home( about a 1/4 mile) I only kept it in 1st gear and drove at 20 mph at 2500 rpm. The transmission was making a noise, like a crackling or popping sort of noise, it wasnt nice. Does anyone know what couldve happened? Burnt clutch? Something with the tranny? Snapped driveshaft? Help please, I wanna know how much the repair will cost me, im calling a truck later today and taking it to the shop. A burning smell did come for a few seconds, and then again after it snapped, once I give a bit of gas( like above 4000 rpm) a burning smell comes
I put it in 1st and had already taken my foot off the clutch and started rolling, everything's normal right. Then I step on the gas and "snap", I freak out, I dont know what happened. I stopped the car and tried driving again, I release the clutch very slowly until I start moving and I give gas and it just wont go, the clutch is slipping I think. I wait about 5 minutes, I try again, it is still slipping but I get the car moving, barely, I drove home( about a 1/4 mile) I only kept it in 1st gear and drove at 20 mph at 2500 rpm. The transmission was making a noise, like a crackling or popping sort of noise, it wasnt nice. Does anyone know what couldve happened? Burnt clutch? Something with the tranny? Snapped driveshaft? Help please, I wanna know how much the repair will cost me, im calling a truck later today and taking it to the shop. A burning smell did come for a few seconds, and then again after it snapped, once I give a bit of gas( like above 4000 rpm) a burning smell comes
Safety Car
Joined: Dec 2007
Posts: 4,974
Likes: 148
From: Magnolia Texas
The fuse in the passenger well, controls the NPP controller, which controls the vacuum solenoid.
With now fuse, the NPP and the Vacuum solenoid do not get power up, and since the normal non powered state of the vacuum solenoid does not vacuum through it, the muffler gates stay wide open. When the controller does have power to it, it powers up the solenoid to allow vacuum through it , and this closes the muffler gates.
When the RPS reach high enough, and you are deep into the throttle pedal, then the NPP cuts to the power to the vacuum solenoid, and this allows the gates to open as long as such demands are meet.
So yes, the gates are controlled by the vacuum off the intake manifold, but you have electronic items controlling the vacuum as well.
Go post #8 to see all the parts that make up the NPP system.
https://www.corvetteforum.com/forums...tuck-open.html
With now fuse, the NPP and the Vacuum solenoid do not get power up, and since the normal non powered state of the vacuum solenoid does not vacuum through it, the muffler gates stay wide open. When the controller does have power to it, it powers up the solenoid to allow vacuum through it , and this closes the muffler gates.
When the RPS reach high enough, and you are deep into the throttle pedal, then the NPP cuts to the power to the vacuum solenoid, and this allows the gates to open as long as such demands are meet.
So yes, the gates are controlled by the vacuum off the intake manifold, but you have electronic items controlling the vacuum as well.
Go post #8 to see all the parts that make up the NPP system.
https://www.corvetteforum.com/forums...tuck-open.html
thanks Dano523! I couldn’t remember the fail position (must be old age).
