When does Dual Mode Exhaust Valve Close? (SS)

[onoahimahi]

Hi - I am trying to understand dual mode exhaust on my newly acquired 2014 2SS. Namely, when does it close? I looked in the exhaust pipe and see that the valve is open for idle and minor reving (up to maybe 2000 RPM). I searched and found lots of discussion on pulling the fuse but if it is generally open at 'casual' RPMs up to 2000, it is already in loud mode, correct? And if cruising on the highway in 6th gear at less than 2000 RPM, it is already in loud mode there too, correct? When does it normally close? And when it is closed, when will it re-open based on performance demands?

I'm not clear how this is supposed to work and there seems to be a bit of confusion in the threads on this topic as well. (Maybe my fuse is already pulled...)

Thanks,
-Scott

[ron123]

Following info was pulled from "GM Authority" and "Autoweek" and some from memory ...
At start:
The Camaro NPP Dual-Mode Exhaust is in loud/bypass mode at engine startup and through 1,500 RPMs (vacuum solenoids off).
Then:
The system uses the engine control module (ECM), body control module (BCM), electronic brake control module (EBCM), EFCM, exhaust flow control valve vacuum solenoid, vacuum reservoir, vacuum lines, 2 exhaust flow control valves and the serial data circuit to perform its functions. Ultimately, the EFCM directs the vacuum solenoid off as vehicle speed increases, throttle position reaches 25 percent or greater, and dentine speed reaches 3500 RPM. In other words, drive the Camaro hard, and you’ll reap the benefits of the dual-mode exhaust. The combination of the above events causes the valves to Re-open, thereby diverting exhaust flow through an un-baffled path inside the mufflers and enhancing engine performance.

A great addition to an already-great car. With our tester's dual-mode exhaust, the Camaro SS is about as subtle as a 12-gauge; it makes no attempt to hide its intentions whether you're at idle or ripping up a freeway on-ramp, and there's even a burbling pop-pop on the overrun when you're slowing down for a light. Yes, it's fun at times (especially when the hand of God is released on the aforementioned freeway on-ramps), but it's just as often overkill.

One feature of the NPP Dual-Mode Exhaust is to lower drone when the engine is under light load cruising on the highway to allow easier conversation and radio listening.
Ron

[JD555]

Basically its open at idle until you hit about 20 mph if accelerating slowly then it closes and will stay closed cruising easy on the pedal. If you accelerate hard it will stay open. If you punch it while cruising it will open. Deceleration it will open around 20-25 and you can hear the exhaust popping. I put a 3 way controller in mine so I can select factory mode, always open and always closed. On trips with the back seat down and long things in my trunk like fishing rods(every week) the drone can sometimes get to me and I will close them or starting up early in the morning (to go fishing) ill close them.

[ZED SLED]

This should give you an idea of how it flows. The fuse for the solenoid control circuit is #8 and is in the trunk fuse box. My fuse #8 is in the glove box so the circuit is always open.

[onoahimahi]

Guys, thanks, that helps. I was able to see the valve close in the driveway when my wife revved the engine up to around 2000 RPM so I know the fuse is not pulled. I love the way it sounds both at idle and on the aforementioned freeway on-ramps..!

Thanks,
-Scott

[Jarret]

It sounds really good when the fuse is pulled

[snarky]

thankfully NEVER

[jrhagen]

NPP on a supercharged car with long tubes and cat delete sounds awesome when open.

[2013blueray]

Originally Posted by JD555

Basically its open at idle until you hit about 20 mph if accelerating slowly then it closes and will stay closed cruising easy on the pedal. If you accelerate hard it will stay open. If you punch it while cruising it will open. Deceleration it will open around 20-25 and you can hear the exhaust popping. I put a 3 way controller in mine so I can select factory mode, always open and always closed. On trips with the back seat down and long things in my trunk like fishing rods(every week) the drone can sometimes get to me and I will close them or starting up early in the morning (to go fishing) ill close them.

How did you add the 3 way...?

[JD555]

I bought the Forza controller. Its not a bad install.

[Hootch]

Some info on doing it yourself.

https://www.camaro5.com/forums/showthread.php?t=318683

[DSEowner]

Originally Posted by JD555

Basically its open at idle until you hit about 20 mph if accelerating slowly then it closes and will stay closed cruising easy on the pedal. If you accelerate hard it will stay open. If you punch it while cruising it will open. Deceleration it will open around 20-25 and you can hear the exhaust popping. I put a 3 way controller in mine so I can select factory mode, always open and always closed. On trips with the back seat down and long things in my trunk like fishing rods(every week) the drone can sometimes get to me and I will close them or starting up early in the morning (to go fishing) ill close them.

Your back seat folds down? Was that new for 2014. I don't see any way to do it on my 2013. Maybe I'm just not looking hard enough.

[CamaroFred]

Originally Posted by DSEowner

Your back seat folds down? Was that new for 2014. I don't see any way to do it on my 2013. Maybe I'm just not looking hard enough.

There is a tab in the middle at the top of the seatback to pull.
Make sure it clicks when you put it back up.

[JD555]

Originally Posted by DSEowner

Your back seat folds down? Was that new for 2014. I don't see any way to do it on my 2013. Maybe I'm just not looking hard enough.

Last time I had it down I had both the lower units from my Yamaha 225 outboards in there to bring them home. I opened the trunk and my brother said are you kidding me. you fit those in there? You can fit a lot in that trunk with the seat down. like said above pull the tab in the middle of the seat up top.