[Djason]

Was curious how they worked compared to my Z06's bi-mode exhaust working off vacuum and obviously some electronics to open/close at certain rpms in stock form. Many years ago I installed the 'Mild to Wild' switch which is cool to have especially with the Akrapovic exhaust I have.

Over the weekend I removed the passenger side electronic actuator to see how it works since it doesn't seem to work off vacuum as my Z06 does. Found out there is a heavy spring that keeps the valves open. Once the car is started, after a few seconds, the actuator closes the valves then reopens depending on the signal it receives during WOT, Sport, Race, etc.

Many of us that have removed the cats and installed aftermarket DP's are not thrilled with the WOT sound of the stock muffler at certain rpms. I'd like to be able to keep mine a sleeper hence the reason for the post.

I wonder if there is a way to keep the valves closed at WOT? Until a quality exhaust system comes out with a better, tuned (non obnoxious) WOT sound, with ZERO drone and quiet during 'normal' driving I'd like to be able to keep the valves closed at all times. Other than the obvious, trying to remove the spring (not sure how after looking how it's integrated) then figure a way to physically block the valves from opening, I'm not sure how to go about doing this.

I'm sure the BCM is part of the equation as nothing we've seen in the ECU has a function to be able to turn on or off the electronics responsible for the opening or closing of the valves.

Any thoughts or suggestions...??

 

[Chris09v]

I wish there was a way to tune it so they only open in track mode. I was thinking of a dual in dual out muffler where the x pipe was with resonators before the tips that could be bypassed with the valves. I'm not sure if the muffler will fit there though. I also like the idea you came up with but I can see it getting even louder than it is currently. I guess the other option is to get rid of the valves all together but I'm not there yet.

 

[Djason]

If the valves stay closed at WOT it's not loud at all. As you know the exhaust is bypassed to a quieter section of the muffler when valves stay closed. For some weird reason a couple weeks ago I made a pull through 3rd gear at WOT to redline while in Tour mode. The valves never opened up. Was a nice surprise, I was like YES, NICE! Was in sleeper mode, making a strong pull with little exhaust note. I would love for it to be like this until, as you said, you decide to run it in Track Mode.

 

[Chris09v]

So is it just constant 12v that keeps them shut?

 

[Djason]

So is it just constant 12v that keeps them shut?

It looks that way Chris. I unplugged them a couple weeks ago thinking they might stay closed but they stayed open because of the spring assembly. Didn't realize how they worked until last weekend.

 

[Chris09v]

It may be easier to just run a toggle switch to keep them powered up and then switch it off when you want to open them up. I'll have to get down there and verify voltage and see what the easiest way to go about it will be.

 

[bomariam1]

With the golf r, it's controlled by the chassis controller and not the engine ECM.

 

[ziominix]

I'd like to play with how the car sounds stock with the valves open all the time, is there a fuse to pull or is the only option to pull the plug at the valves themselves?

 

[bomariam1]

just got my v today, the sound with flap open is fantastic.

 

[Chris09v]

Not sure if it would sound as good if you just unplugged it, I don't think the enhanced sound would play through the speakers so you would purely hear the exhaust.

 

[frogjbm]

I agree...this is my approach as well...I want the valves to be open at all times and stop closing once in 4th gear...I want to always hear the exhaust note, it sounds damn good for a V6 IMO. Anyone know how to do this...is it as simple as unplugging the Valves 12V wiring and they just stay open all the time or what??

 

[Djason]

Yes in stock form the exhaust sounds great when the valves open at start up, at idle or WOT. It's when you delete the cats and install DP's is when it becomes TOO DAMN LOUD unless your a F&F fan which I am not. It is still a Cadillac after all not a Honda. Showing my age I guess. I do enjoy a quality, tuned V6 sound. Just not the tin can sound at WOT when the cats are deleted.

 

[bomariam1]

With my golf r, I did open the flap and cancel the soundaktor(the speeker that give engine sound in compartment) by programing the chassis ECM, does GM cars have the same thing?

 

[frogjbm]

No GM does not generate engine/exhaust noise through the speakers...thank God because that's the gayest thing ever.

 

[sraesmit]

INFO on the exhaust -


Engine Exhaust Flow Valve System
The engine exhaust flow control valve system has two subsystems:

The exhaust tail pipe flow control valve system. Also known as the exhaust sound quality valve control system.

The cylinder deactivation exhaust flow control valve system. Also known as the active fuel management (AFM) exhaust flow valve control system.

Exhaust Tailpipe Flow Control Valve System
The exhaust tailpipe flow control system is used to tune the exhaust note for high performance vehicles. The vehicle is equipped with two tailpipe exhaust valves. One in the left tailpipe and one in the right tailpipe. Each exhaust tailpipe valve is installed in the low restriction exhaust path of a dual outlet muffler, near the exhaust tip.

When a tailpipe exhaust valve is open, the low restriction exhaust path is opened to the atmosphere, and the exhaust note becomes more aggressive.

An output circuit from the chassis control module is used to control the actuator that opens the left and right exhaust tailpipe valves. The exhaust flow control valve opens and closes when the chassis control module commands the actuator by pulse width modulation of the control signal.

To provide a more aggressive exhaust note when the vehicle is started, the exhaust tailpipe valves are opened during an engine crank event during specific modes of operation if that option is available. Once the engine is running, accelerator pedal position, transmission gear and engine speed are used to determine the commanded state (open or closed) of the exhaust tailpipe valves.

There are four specific exhaust performance modes that result in different behavior of the exhaust tailpipe valves. These modes are:

Note: You may notice an exhaust tone change due to the AFM system activation. Review the cylinder deactivation exhaust flow control system operations for additional details.
Winter/Eco Mode: Exhaust tailpipe valves will be closed at all times when the engine is running.

Tour Mode: Exhaust tailpipe valves are closed when the engine is idling and during normal/non-aggressive driving. Valves open during aggressive driving.

Sport Mode: Exhaust tailpipe valves are open when the engine is idling and during most driving scenarios. See note above.

Track Mode: Exhaust tailpipe valves are open at all times. See note above.

It is possible to personalize the exhaust sound. When engine sound enhancement is turned off via the personalization menu, the exhaust tailpipe valves will be put into track mode no matter which vehicle mode (Winter/Eco, Tour, Sport, or Track) is displayed on the drivers instrument panel.

Cylinder Deactivation Exhaust Flow Control Valve System
As a means to improve fuel economy, the engine management systems in some vehicle applications include provisions to deactivate half of the engine cylinders under certain operating conditions. For example, under a light load. The cylinder deactivation exhaust flow control valve subsystem is used to mitigate the impact that powertrain engine cylinder deactivation (active fuel management) has on the quality of the exhaust sound. When the active fuel management system is in operation, the cylinder deactivation exhaust flow control valve subsystem takes over control of the exhaust tailpipe flow control system. When active fuel management is operating, the exhaust tailpipe flow control valves are commanded shut resulting in a quieter exhaust note until the active fuel management system deactivates with increased throttle demand at which time the exhaust tailpipe flow control returns to the operational status determined by the vehicle specific mode that is being used.

The cylinder deactivation exhaust flow control system controls the undesirable exhaust noise generated during the cylinder deactivation process. This is achieved through the use of up to two electronically actuated cylinder deactivation exhaust flow control valves in the vehicle exhaust system. The cylinder deactivation exhaust flow control valves are commanded to the closed position by a pulse width modulated signal from the chassis control module in response to active or pending engine cylinder deactivation. When the cylinder deactivation exhaust flow control valves are in the closed position, the engine exhaust flows through a hole machined in the plates integral to the valves. When the engine is operating on all cylinders, the cylinder deactivation exhaust flow control valves are commanded to the open position in order to minimize exhaust restriction. To provide some control hysteresis, once the cylinder deactivation exhaust flow control valves have been commanded to the closed position, they are not reopened until the engine torque reaches a calibrated minimum value that is determined as a function of the driver selectable performance mode.

 

[roadpie4u]

An output circuit from the chassis control module is used to control the actuator that opens the left and right exhaust tailpipe valves. The exhaust flow control valve opens and closes when the chassis control module commands the actuator by pulse width modulation of the control signal.

To provide a more aggressive exhaust note when the vehicle is started, the exhaust tailpipe valves are opened during an engine crank event during specific modes of operation if that option is available. Once the engine is running, accelerator pedal position, transmission gear and engine speed are used to determine the commanded state (open or closed) of the exhaust tailpipe valves.

This is the reason why I'm curious about getting a hold of the active exhaust system and goofing around with it - if its a modulated signal (PWM) then there's no reason the valves can't be set to any percentage of open or closed - why use a PWM signal if the valves are either open or closed (which could just be a 'dumb' solenoid, but they state actuator)?

You could always get a full 'normal' catback and use the valves with aftermarket turbos/downpipes to do wastegate dump to atmosphere...

 

[ziominix]

INFO on the exhaust -


Engine Exhaust Flow Valve System
The engine exhaust flow control valve system has two subsystems:

The exhaust tail pipe flow control valve system. Also known as the exhaust sound quality valve control system.

The cylinder deactivation exhaust flow control valve system. Also known as the active fuel management (AFM) exhaust flow valve control system.

Exhaust Tailpipe Flow Control Valve System
The exhaust tailpipe flow control system is used to tune the exhaust note for high performance vehicles. The vehicle is equipped with two tailpipe exhaust valves. One in the left tailpipe and one in the right tailpipe. Each exhaust tailpipe valve is installed in the low restriction exhaust path of a dual outlet muffler, near the exhaust tip.

When a tailpipe exhaust valve is open, the low restriction exhaust path is opened to the atmosphere, and the exhaust note becomes more aggressive.

An output circuit from the chassis control module is used to control the actuator that opens the left and right exhaust tailpipe valves. The exhaust flow control valve opens and closes when the chassis control module commands the actuator by pulse width modulation of the control signal.

To provide a more aggressive exhaust note when the vehicle is started, the exhaust tailpipe valves are opened during an engine crank event during specific modes of operation if that option is available. Once the engine is running, accelerator pedal position, transmission gear and engine speed are used to determine the commanded state (open or closed) of the exhaust tailpipe valves.

There are four specific exhaust performance modes that result in different behavior of the exhaust tailpipe valves. These modes are:

Note: You may notice an exhaust tone change due to the AFM system activation. Review the cylinder deactivation exhaust flow control system operations for additional details.
Winter/Eco Mode: Exhaust tailpipe valves will be closed at all times when the engine is running.

Tour Mode: Exhaust tailpipe valves are closed when the engine is idling and during normal/non-aggressive driving. Valves open during aggressive driving.

Sport Mode: Exhaust tailpipe valves are open when the engine is idling and during most driving scenarios. See note above.

Track Mode: Exhaust tailpipe valves are open at all times. See note above.

It is possible to personalize the exhaust sound. When engine sound enhancement is turned off via the personalization menu, the exhaust tailpipe valves will be put into track mode no matter which vehicle mode (Winter/Eco, Tour, Sport, or Track) is displayed on the drivers instrument panel.

Cylinder Deactivation Exhaust Flow Control Valve System
As a means to improve fuel economy, the engine management systems in some vehicle applications include provisions to deactivate half of the engine cylinders under certain operating conditions. For example, under a light load. The cylinder deactivation exhaust flow control valve subsystem is used to mitigate the impact that powertrain engine cylinder deactivation (active fuel management) has on the quality of the exhaust sound. When the active fuel management system is in operation, the cylinder deactivation exhaust flow control valve subsystem takes over control of the exhaust tailpipe flow control system. When active fuel management is operating, the exhaust tailpipe flow control valves are commanded shut resulting in a quieter exhaust note until the active fuel management system deactivates with increased throttle demand at which time the exhaust tailpipe flow control returns to the operational status determined by the vehicle specific mode that is being used.

The cylinder deactivation exhaust flow control system controls the undesirable exhaust noise generated during the cylinder deactivation process. This is achieved through the use of up to two electronically actuated cylinder deactivation exhaust flow control valves in the vehicle exhaust system. The cylinder deactivation exhaust flow control valves are commanded to the closed position by a pulse width modulated signal from the chassis control module in response to active or pending engine cylinder deactivation. When the cylinder deactivation exhaust flow control valves are in the closed position, the engine exhaust flows through a hole machined in the plates integral to the valves. When the engine is operating on all cylinders, the cylinder deactivation exhaust flow control valves are commanded to the open position in order to minimize exhaust restriction. To provide some control hysteresis, once the cylinder deactivation exhaust flow control valves have been commanded to the closed position, they are not reopened until the engine torque reaches a calibrated minimum value that is determined as a function of the driver selectable performance mode.

I've been all through the settings menus and can't find the ability to set the exhaust mode independent from the drive mode. That's one thing I really miss from my C7, the ability to adjust the exhaust tone, and steering effort independent from the suspension setting. I always ran exhaust open, steering effort set to sport and then just changed the suspension depending upon what road I was on.

 

[Hib_Halverson]

INFO on the exhaust -

Engine Exhaust Flow Valve System
The engine exhaust flow control valve system has two subsystems:

The exhaust tail pipe flow control valve system. Also known as the exhaust sound quality valve control system.

The cylinder deactivation exhaust flow control valve system. Also known as the active fuel management (AFM) exhaust flow valve control system.(snip)

The LF4 engine in an ATS-V does not have cylinder deactivation, thus, there is no "exhaust flow control" valve in the ATS-V exhaust system. Actually, you can see that for yourself simply by looking under the car at the exhaust system.

Operation of the tail-pipe valves on an ATS-V cannot be "personalized". On an ATS-V there is no menu selection for: settings>driving mode>engine sound management.

 

[NormV]

The LF4 engine in an ATS-V does not have cylinder deactivation.

Operation of the tail-pipe valves on an ATS-V cannot be "personalized". On an ATS-V there is no menu selection for: settings>driving mode>engine sound management.

I'm sure some computer can be manipulated, whether it be through HPTuners or the like. Trifecta is doing something similar with the CTS VSport in different modes.

 

[Djason]

There is no table in HPTuners to manipulate the bi-mode exhaust valves. As others have stated it's part of the BCM settings which I'm unaware of any way to change those settings. Guess the only way after doing DP's to eliminate some of the unwanted "ricer" sound is to wait for an aftermarket muffler/cat back system or dive into the stock muffler to try and insulate/baffle the interior pipes and make an actual muffler instead of just an open can with pipes.