NPP Problem - 2009 Base
Thread Starter
Cruising
Joined: Jun 2013
Posts: 14
Likes: 2
From: Northville MI
NPP Problem - 2009 Base
2009 Base Corvette with NPP exhaust. I am the original owner.
After driving with exhaust closed for 20 to 30 minutes, the flaps will open on their own (at low speed) and will not close unless I shut off the car and restart.
Could it be the Vacuum Actuator or the Bi-Mode Exhaust Control Module?
I have checked all of the vacuum connections and everything seems to be in order. Where is the Bi-Mode Exhaust Control Module located? I want to check the connections on that.
I had a Mild to Wild controller/switch on the car and removed it as to narrow down the problem. When the flaps opened on their own, the M2W controller had no effect.
Removing it had no effect on the flaps opening under 3500 RPM's.
Looking for help to resolve the issue.
After driving with exhaust closed for 20 to 30 minutes, the flaps will open on their own (at low speed) and will not close unless I shut off the car and restart.
Could it be the Vacuum Actuator or the Bi-Mode Exhaust Control Module?
I have checked all of the vacuum connections and everything seems to be in order. Where is the Bi-Mode Exhaust Control Module located? I want to check the connections on that.
I had a Mild to Wild controller/switch on the car and removed it as to narrow down the problem. When the flaps opened on their own, the M2W controller had no effect.
Removing it had no effect on the flaps opening under 3500 RPM's.
Looking for help to resolve the issue.
Safety Car
Joined: Aug 2017
Posts: 4,243
Likes: 1,133
From: North Myrtle Beach SC
Pull the vac hoses off of your valves. Close the valve with your hand. Put a finger on the hose nipple. If the valve is good it will stay closed. If valves check ok, go to the module by the tail lights.
Safety Car
Joined: Aug 2017
Posts: 4,924
Likes: 2,334
From: Etobicoke (Toronto) Ontario
The most common failure is the vacuum solenoid. Sounds like yours is circling closer to the drain. It's located behind the passenger side taillights I believe and replacing it is DIY. And it's not that expensive. There's a few writeups on the forum on how to do it and probably some YouTube vids, so a Google search should find those.
Le Mans Master
Joined: Aug 2006
Posts: 5,379
Likes: 608
From: Charlotte NC
It’s the solenoid. Amazon has it so you get get it ASAP. Very easy install. Lots of videos.
Is used this one for ‘11 GS.
this is the Amazon description:
Is used this one for ‘11 GS.
this is the Amazon description:
GM Genuine Parts 25794610 Engine Intake Manifold Tuning Vacuum Control Solenoid Valve
Thread Starter
Cruising
Joined: Jun 2013
Posts: 14
Likes: 2
From: Northville MI
The most common failure is the vacuum solenoid. Sounds like yours is circling closer to the drain. It's located behind the passenger side taillights I believe and replacing it is DIY. And it's not that expensive. There's a few writeups on the forum on how to do it and probably some YouTube vids, so a Google search should find those.
Safety Car
Joined: Aug 2017
Posts: 4,924
Likes: 2,334
From: Etobicoke (Toronto) Ontario
It's called the Exhaust Tail Pipe Flow Valve Control Module.. If you look at the first post in this thread, there's a pic of the location. https://www.corvetteforum.com/forums...is-module.html BTW, I don't recall ever hearing about one of those failing, but like all electronics, I suppose it's possible.
Thread Starter
Cruising
Joined: Jun 2013
Posts: 14
Likes: 2
From: Northville MI
It's called the Exhaust Tail Pipe Flow Valve Control Module.. If you look at the first post in this thread, there's a pic of the location. https://www.corvetteforum.com/forums...is-module.html BTW, I don't recall ever hearing about one of those failing, but like all electronics, I suppose it's possible.
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It's called the Exhaust Tail Pipe Flow Valve Control Module.. If you look at the first post in this thread, there's a pic of the location. https://www.corvetteforum.com/forums...is-module.html BTW, I don't recall ever hearing about one of those failing, but like all electronics, I suppose it's possible.
Dude, when don't they fail, is the question instead.
Hence GM designed them backwards to sell more replacement parts, so when car is started, it powers up to allow allow the vacuum through it, and when you shut the car off (or Npp controlers kills the power to it for a few seconds to go into loud mode), it then powers down to close the vacuum through it instead.
So since it spends most of it time in an energized state to keep the gates closes when the motor is running, pretty much burns itself up in a few year isntead.
Safety Car
Joined: Aug 2017
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From: Etobicoke (Toronto) Ontario
Race Director
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Safety Car
Joined: Aug 2017
Posts: 4,924
Likes: 2,334
From: Etobicoke (Toronto) Ontario
no factory cars were right hand drive
“Behind the passenger side taillight, mounted on the bumper bar. Its under a waxy, rubbery cover.
Remove the inner passenger taillight and reach down to the bumper. You will feel the cover. It is underneath that cover.”