Anyone do a Exhaust Valve Fuse Pull on 4BW?

[raptor5244]

Curious if anyone has tried this on a 4BW yet? Curious if it works the same as the Corvettes and Camaros I have owned. Does it throw a CEL? It looks like it is fuse 34.

 

[WONT TAP]

This will set codes on the Blackwings.

 

[raptor5244]

This will set codes on the Blackwings.

Thanks for the confirmation. Not sure if would be an improvement at all. I know of some of my Camaros and Corvettes sounded better since the valves would partially close at certain rpms. Probably to meet some drive by ordinance....

 

[strohw]

I'd think you'd want it working. It opens when you get on the throttle but it closes and stops a very obvious drone while your cruising along. Sometimes it takes it a little bit to close while cruising so it gives a good impression of what it would be like if it was open all the time.

 

[CBH]

You don't need to pull the fuse. MyMode survives ignition cycles, so you can set it to to the loudest setting and it'll still be there when you start it next time.

The trick is leaving it in MyMode. If you switch to any other mode, it'll go back to Tour upon the next start.

This is actually a blessing in disguise. You could leave it loud in VMode, but avoid waking up the other people in your house and the neighbors when you start it next. Clever.......

 

[Mcard23]

Curious if anyone has tried this on a 4BW yet? Curious if it works the same as the Corvettes and Camaros I have owned. Does it throw a CEL? It looks like it is fuse 34.


View attachment 17575

Was wondering the same thing, I had mine pulled on my Camaro almost immediately. Definitely made a difference when cruising even in “track” exhaust mode.

 

[raptor5244]

You don't need to pull the fuse. MyMode survives ignition cycles, so you can set it to to the loudest setting and it'll still be there when you start it next time.

The trick is leaving it in MyMode. If you switch to any other mode, it'll go back to Tour upon the next start.

This is actually a blessing in disguise. You could leave it loud in VMode, but avoid waking up the other people in your house and the neighbors when you start it next. Clever.......

Yep, I use MyMode. I was curious how the 4BW would sound without the GM tuning of the exhaust valves. These exhaust valves are tuned to partially or fully close in certain situations. RPM, speed, etc. The 4BW sounds pretty good right off idle, it has decent bark to it but once the RPM climbs a little bit it softens up quite a bit. With the exhaust in Track mode the overrun burbles are actually overdone in my opinion. It just gurgles non-stop instead of fire off a crackle hear and there. On the V8s it sounds much better since it has a "crackle" sound instead of "gurgle."
On my ZL1 and C7 Corvette when you pull the fuse you can tell right away that the exhaust valves partially close at lower RPMs, even in Track mode. This is done to meet drive by noise ordinances and in some cases to remove some of the drone you get are certain RPMs, for example, when cruising on the highway. That said, I think it they sound much better with the valves disabled/wide open all the time.

Anyway, I was just curious on the 4BW but since it throws a code I will let it go.

 

[raptor5244]

Was wondering the same thing, I had mine pulled on my Camaro almost immediately. Definitely made a difference when cruising even in “track” exhaust mode.

Yep, same here. Not sure if the LF4 would yield the same result but it looks like the fuse pull game is over unless you get a tune. I think the C8 dual mode exhaust throws a code now as well if you pull the fuse.

 

[MatthewAMEL]

Everyone is saying it 'sets a code', but does it trigger the CEL? Lots of things set codes that do not trigger the light.

"Track" exhaust mode and pulling the fuse are not the same thing. In track mode, the valve still closes/modulates. With a fuse pull, the valve stays open all the time.

 

[raptor5244]

Everyone is saying it 'sets a code', but does it trigger the CEL? Lots of things set codes that do not trigger the light.

"Track" exhaust mode and pulling the fuse are not the same thing. In track mode, the valve still closes/modulates. With a fuse pull, the valve stays open all the time.

It looks like you have a 5 so it if is the same as the Camaro ZL1 and Corvette Z06 maybe you can pull Fuse 51 without a CEL? No idea. The 4BW is new to me and look to have a different setup, more fuse blocks, etc.

 

[CBH]

Good to learn about the fuse. So it's fuse 51 on the 5BW ?

Did you get that diagram from shop manual ?

Do we know if "setting the code" and visible CEL the same thing, or can the code be set without CEL ?

 

[shbox]

Good to learn about the fuse. So it's fuse 51 on the 5BW ?

Did you get that diagram from shop manual ?

Do we know if "setting the code" and visible CEL the same thing, or can the code be set without CEL ?

Just as a general rule in on-board diagnostics, not all codes cause the CEL to come on. Normally, the factory manual info tells you what happens when a code is detected (including whether it commands the CEL to come on).

 

[raptor5244]

Good to learn about the fuse. So it's fuse 51 on the 5BW ?

Did you get that diagram from shop manual ?

Do we know if "setting the code" and visible CEL the same thing, or can the code be set without CEL ?

I found the fuse block diagrams in the regular owner manuals. Not sure on the CEL.

 

[CBH]

Exhaust Valves on CT5 BW are Fuse 34 in the dash by driver's door.

I just pulled it and went for a very short test drive but did not notice much difference. No CEL.

I thought i might have found a cheap, easy solution to make it louder. I do appreciate learning about this though. If I ever get the exhaust redone, this will let me know how much its closing at other times/RPMs.

 

[raptor5244]

Exhaust Valves on CT5 BW are Fuse 34 in the dash by driver's door.

I just pulled it and went for a very short test drive but did not notice much difference. No CEL.

I thought i might have found a cheap, easy solution to make it louder. I do appreciate learning about this though. If I ever get the exhaust redone, this will let me know how much its closing at other times/RPMs.

View attachment 17641

Nice. Yeah, it doesn't actually make it louder per se, it just removes the programming they have dialed in to close or partially close the valves at various speeds and RPM. On my ZL1 I would notice a pretty significant drop in exhaust volume when you dip below around 2200rpm. You could hear this little, "hitch" when the valves transition and I found it annoying. Most don't notice it but I preferred the valves wide open all the time at all RPMs and speeds.

The big concern was if you pulled the fuse then would you get annoying drone at highway speeds. I never noticed any difference in the ZL1.

If you drive it a bit more and and then put the fuse back in you may be able to tell the RPM levels where the valves close. You should get a little more exhaust volume at lower RPMs.

 

[CBH]

Drove it quite a bit tonight. It seemed barely perceptibly louder at highway speeds, but still nowhere close to droning.

And I was wrong - the CEL was hiding behind the steering wheel on the upper right side of the dash. I'll plug it back in tomorrow and reinstall the cover. Hopefully CEL goes out. Dealer will still see the code, but who cares..........

Good news - I can keep the stock valves and likely not have to worry about it making it that much quieter.

@raptor5244 - my plans were to put a straight pipe on the loud side, so this is good news if I can ever get that done !!

 

[raptor5244]

Drove it quite a bit tonight. It seemed barely perceptibly louder at highway speeds, but still nowhere close to droning.

And I was wrong - the CEL was hiding behind the steering wheel on the upper right side of the dash. I'll plug it back in tomorrow and reinstall the cover. Hopefully CEL goes out. Dealer will still see the code, but who cares..........

Good news - I can keep the stock valves and likely not have to worry about it making it that much quieter.

@raptor5244 - my plans were to put a straight pipe on the loud side, so this is good news if I can ever get that done !!

Maybe you can clear it with a cheap ODB code reader? If you disconnect the battery for a bit it may reset as well.

 

[CBH]

I have a code reader, but today the light went out on its own after several ignition cycles. Its all put back together, so hopefully the dealer won't give me a hard time at my first (free) oil change.