budgreen3564

Is the sound louder with this fuse out than engine management set to
"track"? In track mode the flaps will close when running WOT on a track?

Jason900rr

I'm pretty sure it's the same thing! I just pulled the fuse but then found out that I could just keep the valves open by putting it in track mode through the sound management.

Speedforhire

You need to set it to Sport Mode. If you leave it in Track Mode it will reset when you turn the car off. Set drive to Sport and sound management to Sport and it will stay open.

........or pull #42 and don't worry about it.

dvilin

With fuse #42 pulled the sound is not louder just constant. The valves stay open 100% of the time. This is the only way to keep the valves open all the time. In any mode they will close at certain RPMs.

Boiler_81

As dvilin said, the valves don't stay open all the time in track mode. Take a look at this post for some links on how the system works.

https://www.corvetteforum.com/forums...post1594275159

budgreen3564

Very confusing. Mine is '17 GS auto. I have engine management mode at track and drive in tour. Is it correct that my track mode exhaust changes at engine shut off? What does it change to?

themonk

depends on what transmission and year you have.

falconhulk

No the statement made above was not correct at all. If you put it in TRACK MODE it will switch back to TOURING MODE when the car is restarted.


If you put the exhaust in track via the infotainment setting, it never changes even if you change MODES. This means you can switch to touring mode and still enjoy the more open exhaust.

Joe_Omega

I have mine set to track in sound management and they stay open all the time with the exception of below 1700 RPM's. If you are cruising along at about 30-35 in 4th gear and RPM's drop below about 1700 it will go quiet until you hit the gas a little.

If you pull fuse 42 they will always be open no matter the condition.

kenownr

JerryU

Nope. The butterfly valves are either open or closed. The computer controls at what RPM. Even in Track Mode they still will close when cruising below (as someone noted) ~1700 rpm. (Note you can have them set at the most aggressive Track setting on all driving modes by a setting in the options menu.) If you pull the fuse they can't close!

In my C6 leaving them open on the Interstate caused an objectionable drone. Even a loud radio was no help. I installed a switch on the C6 to by-pass the fuse instead of just pulling it. Plan to put a similar toggle switch in my Grand Sport mounted in the front cup holder (as I did on my C6) to by-pass the fuse after the car arrives AND I find the time!

capecodvette

not that confusing. set for Sport, it will stay in Sport.

joemessman

Mine is an A8 with npp and a Borla Xpipe. I have the fuse removed. I always drive in track mode and is set to Track mode in vehicle settings. When I turn the car on it is always back to Tour.

LT1 Z51

Since the valves are now electronically operated they are not just open or closed. They can be anything in between (I think there are 5 steps programmed; Closed, 25%, 50%, 75%, Open).

The valves are partially closed below 35 MPH (and certain RPMs in gears that don't go under 35 MPH). Silent and Tour close the valves at these speeds, Track and Sport open them slightly. Once you hit 35, Tour opens more than Silent, but less than Sport, and Track opens them more than Sport.

JerryU

That's true they COULD BE but my understanding from when it was discussed very early on they are ONLY open or shut, agreed now by electric motors! There is feedback that caused some early issues in that regard but believe it's still open or closed valves. Have never seen a reference that said it varies the amount of opening.

PS: Saved this since Tenneco is one of my good welding related customers:

“…the exhaust system will include the option of two electrical valves in the tailpipes, tuned specifically for enhanced sound quality. During normal driving conditions, these extra valves will be closed, but they’ll open during harder acceleration, creating lower backpressure, more engine power, and that beautiful Corvette signature sound.
“The Corvette is one of America’s iconic automobiles, and Tenneco could not be more excited and pleased to partner with Chevrolet to provide a combination of performance attributes, including improved fuel economy, power and the vehicle’s signature sound,” said Tim Jackson, Tenneco’s chief technology officer. “Additionally, the program gives Tenneco an opportunity to demonstrate our advanced exhaust technology on one of the highest performance vehicles available in the market.”
Tenneco supplies ride performance and clean air technologies for GM cars and trucks around the world. The Corvette’s electric valves will be made in Spain, and the other system components will be manufactured in Nebraska and Indiana. Tenneco’s Smithville, Tennessee plant will have the honor of hosting the final assembly of the exhaust system."

Doesn't say specifically that it is only open or closed but believe it does in another reference. They still call it Bimodal, not Variable-Modal!

LT1 Z51

Logic would dictate that it would be extremely difficult to have 4 settings without variable valves.

Just think about it. I already have two states at idle. How do I make Tour sound different than Sport if my Tour valves are closed at idle and Sport are open. Remember above 35 MPH we have 4 distinct sounds.

JerryU

Might be easy, the Tenneco device may be able to do it BUT I don't believe GM software does!

Found this on Page 9-905 of the 2014 Service Manual:
The exhaust flow valve opens and closes when the chassis control module commands... Once the engine is running, accelerator pedal position, transmission gear and engine speed are used to determine the command state (open or closed) of the exhaust valves.
There are 4 exhaust performance modes:
1) Winter/Eco Mode: Valves are closed at all times when engine is running.
2) Tour Mode: Valves closed at idle and during normal non-aggressive driving
3) Sport Mode: Valves open at idle and during most driving (I drive in Sport 95% of the time and sure sounds like they are mostly closed when cruising!)
4) Track Mode: Valves open all the time! (Even the GM Service Manual can be wrong-or that was the planned case but believe they close below 1500/1700 rpm! At least when cruising in 7th on the highway they sound closed.)

redman76

Let me throw this out. If they are either open or closed until a certain RPM (no in between), why does the tone noticeably change at idle when switching from Touring to Sport mode? 2017 Grand Sport M7

budgreen3564

Just ran an errand in the car. This is correct. My drive is set on Tour, and my exhaust is set to Track. It stays that way after shutdown.

JerryU

See what I just added to my prior response (#17) that I found in the 2014 Service Manual (above.) In Tour valves are closed at idle and in Sport open!

I think I'm correct when cruising in Track in 7th gear that they are closed because it sounds that way. But perhaps the sound is the same because there is little gas flow at 1200/1300 rpm!

Have to see if some brave soul will hang out an open hatch and look or safer use a small camera! Actually, someone with a Mild to Wild can validate if the sound is the same when cruising in Track Mode and the fuse is bypassed!