When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I had my car inspected. When I went to pick it up they told me the exhaust valves appeared to be stuck in the open position. I have a switched Mild To Wild switch on it. Flipped it on and off and they were still open. Disconnected the switch and they are still in the open position. What is the fix for this? Can those valves in the exhaust be replaced? Is there something I am not aware of to be checking?
It's almost certainly the vacuum solenoid that's fused in the open position. Sometimes the EXH MDL fuse will blow, sometimes not. The vacuum solenoid is relatively inexpensive and is DIY with a bit of work. It's behind the passenger side (IIRC) taillights. There are quite a few posts on replacing it.
Same happened to me, but before you purchase a new solenoid, try taking it out and cleaning up the contacts. This worked for me over a year ago and it's still working. Just clean everything up and reinstall and if it still doesn't work then buy the valve.
I had the same issue. Valves would close for a bit and then pop open. I ordered the actuator from Rock Auto. Came promptly and I just replaced it yesterday. About a half hour job and all is well with the NPP system. Working fine now. Good luck.
My question to this group is, if the solenoid is not working, could the valves close and not open? Frankly, when I hit >3000rpm, the valves don't seem to open. At least I don't hear any difference any longer. It's not the fuse and I removed the MTW switch. They definitely close after I start the car as I can see and hear them. Any thoughts?
Last edited by dcolehome; Aug 3, 2021 at 12:01 AM.
My question to this group is, if the solenoid is not working, could the valves close and not open? Frankly, when I hit >3000rpm, the valves don't seem to open. At least I don't hear any difference any longer. It's not the fuse and I removed the MTW switch. They definitely close after I start the car as I can see and hear them. Any thoughts?
The solenoid has 2 failure modes: fused open and fused closed. Fused closed, the butterflies close when you start the car and stay closed as long as it's running. Fused open, the butterflies stay open all the time. Yours seems to be fused closed.
Check the vacuum connector on the exhaust side. It’s like a small nipple that is attached to the hose. Mine had a tear in it and it was just a $12 part.
Check the vacuum connector on the exhaust side. It’s like a small nipple that is attached to the hose. Mine had a tear in it and it was just a $12 part.
Something you might check if the butterflies stay open. Vacuum is needed to close them. The OP's stay closed when the car is running, so unless someone bypassed the solenoid, the only way this can happen with the fuse pulled is if the solenoid is stuck closed.
You can also bypass the switch and connect the hoses together. Light throttle-high vacuum valves will be closed. Hammer the throttle-low vacuum valves open.
Does anyone know the GM part number for the Exhaust Solenoid? I was able to find one for the Z06 but it does not say if that fits multiple models. Mine is a 2011 GS 6.2l
Does anyone know the GM part number for the Exhaust Solenoid? I was able to find one for the Z06 but it does not say if that fits multiple models. Mine is a 2011 GS 6.2l
Doesn't directly answer your question, but the vacuum solenoid is not unique to GM cars. Here's a write up using one for German cars which claims to plug right in and appears to be identical, and it's less expensive @ $19.97, free deliver within US. You could PM the OP from the post below as well to verify fit. https://www.corvetteforum.com/forums...y-special.html
Thank you all for your comments. I just ordered a Non-GM compatible part: Topaz, DFD-64015. $20 with free shipping. I will report back how it works. There was an earlier post and the member said it works so giving it a shot.
NPP Not Working
