GTB/ZR-1

I just had the exhaust put on my ‘20 Z51 & it only operates with the valves open. All the factory valve hardware was transferred over—so not sure why the valves are dead.

Anyone have this issue or know of a fix? I also PM’d Fabspeed earlier today, as well.

Kracka

Have you performed the valve relearn procedure?

GTB/ZR-1

Is that required for the valves to work? Excuse my ignorance, if so! lol

MarkMeHopeful

I'm not sure what you mean by "it only operates with the valves open". Does that mean the valves don't actually move (are stuck open) or what? If the valves aren't moving I would bet on an installation problem.

The relearn procedure would be done by the dealer and it is to teach the computer about the new valve positioning. It is done to eliminate a CEL on the new exhaust. That should also be done, but it doesn't sound like that is your problem.

GTB/ZR-1

^^^

Correct—the valves are stuck open.

Kracka

Possibly. Your dealership can do it for you (~$100), or you can purchase a bidirectional scan tool capable of it, such as the Launch X341: Not necessarily; I was working with a local here and his Borla valves would remain "stuck" open until the relearn procedure was completed.

Kracka

Did you by chance try manually moving the valves prior to installation to ensure they were not seized in place?

Fabspeed_Motorsport

Sorry to hear you are having issues with the valves after installation! As others have pointed out it is most likely because the valves need to be relearned. Once the procedure is complete, you will regain full functionality.

It is most likely caused by the valves actuating after the servos have been removed from the OEM valves, if triggered by any number of things during installation, it will require a relearn. Super easy procedure, and should only take 10-15 min!

jwt1603

Just remember sometimes it takes a few tries before the relearn “takes”.

Kracka

Yes, it also has to do with the valves themselves wearing in and loosening up a bit.

GTB/ZR-1

Thanks, everyone—it’s next on my list. I’ll report back on the outcome.

Andybump

The valves are part of the muffler. The actuators are what are transferred to the new muffler. But if the valves are stuck in a position, you should be getting a CEL indicating an issue. The point of the relearn is for the system to "learn" the valve travel. Once learned, it will use that to detect when a valve travel deviates from the the learned travel. If it s not moving at all, that should trigger a CEL. I would be going back to the shop that installed it. Why would they let you leave if the valves were not working?

MarkMeHopeful

I agree with Andy. If a valve is actually stuck open you should be getting a CEL. A relearn won't help you if it's stuck open, but if you don't have a CEL what make you believe it is stuck open? I think we're missing a piece of the story here.

Corvetteexhaustsystems

This is a dummy point but I've seen this happen...Did you make sure to order the valved Fabspeed exhaust and not the Supersport version with no valves?

Lastly, if you have the valved exhaust and your relearn didn't take, make sure the wiring harnesses are correctly plugged into the electronic actuators and they didn't become loose.

One final tip on the relearn procedure. Some manufacturers have suggested to make sure the car is fully warmed up to operating temperature before attempting the relearn proceedure.

GTB/ZR-1

Sounds like I need to further clarify what’s (not) happening: when changing modes from tour to sport or track (or Vice-Versa)—nothing happens.
Also- it’s in the open position because it’s loud & the V4 mode kicks in, that odd harmonic is there.

And, yes—it is most certainly the valved exhaust.

It has not thrown a CEL up to this point (I’ve only put ~25 mi on it so far) & the relearn procedure has not been done yet—which is on my docket to get done.

I appreciate all the feedback—hopefully a simple solution awaits…

Andybump

So then, none of the four valves - the two Cylinder Deactivation Exhaust Flow Control Valves nor the two Tailpipe Flow Control Valves are closing (as you know, all the valves are supposed to close when V4 kicks).

Did you get the Fabspeed Valvetronic muffler? Looks like it does not have any Cylinder Deactivation Exhaust Flow Control Valves, but instead replaces the actuators with simulators. So only the tailpipe flow control valves should be active, if that is what you have.

Andybump

You may be able to visually verify if the valves are moving. I can with the OEM muffler. I just had to lay on the floor with my phone and key fob, and do a remote start - with the car previously turned off in Tour mode. When all is working properly, the valves on the OEM system will always (always) default to open when the ignition is off - and they will remain open during the very brief crank event, but they will immediately close if the car has started in Tour mode (which it will default if shut off in any Mode except MyMode or Sport Mode). I have attached a photo and a video where you can see my valve move from the open position to the closed position immediately after the crank event. I do not know if you muffler will have the same structure that allows you to see them move.

GTB/ZR-1

[QUOTE=Kracka;1607290995]Possibly. Your dealership can do it for you (~$100), or you can purchase a bidirectional scan tool capable of it, such as the Launch X341:
My buddy has one similar—is there an online instruction procedure available that you know of, please? Thank you 👍🏼

Andybump

[QUOTE=GTB/ZR-1;1607307280]With a scan tool the procedure is hook it and then activate the appropriate procedure. The computer does the rest. There is a procedure for each of the two different valve pairs.

GTB/ZR-1

[QUOTE=Andybump;1607307410]Fantastic—thank you!

But completed in 10 secs? The dealer states that it could take a few hours?