engine chirp between 4cyl and 8cyl

FL335i · December 7, 2014

Noticed when I have my windows down and it's quiet outside I can hear chirping from the engine bay. It seems to be when the engine shifts from 4cyl to 8cyl. Sounds like a belt chirp. Anyone else?

stevev · December 7, 2014

that's the exhaust valve or flapper valve some people call it, it's mounted along the exhaust pipe just beyond the muffler. If you clamp it open, the chirp will go away. Do a search on here and you will see.

Some dealers have replaced entire exhaust systems for owners, only to have the noise come back a few thousand miles later. That seems like a big waste of money on GM's behalf.

bluvalley · December 7, 2014

Yes, it's the exhaust flapper. Clamp it open and it disappears, you just have more of a drone in the cabin. GM replaced my exhaust and it returned abut 200 miles later. The don't seem to want to rectify the situation at this point.

It's a bummer.

FL335i · December 8, 2014

Cool. Ya. Ive seen the flapper valve. Not a big deal for me. Just curious wth was causing it. Im not going to even worry bout it. Pretty silly replacing exhausts for that. Its gonna happen again. Unless they have a redesign, whats the point.

dcoates01 · December 16, 2014

Have the same issue. have been battling with the dealership about this. Im not comfortable with them clamping it open since its a lease truck. That valve (IMO) creates higher backpressure for the engine when you are in 4 cylnider mode. the chirp comes from when the valve opens back up.

GM has replaced my muffler once and it came right back. It gets louder over time also. They have been tying to talk with TAC about this and find a fix.

I just got off the phone with my laywer about this and he is wanting to look into a lemon-law or customer compensation case for loss of vehicle value. Not sure I want to take it that far, but ther is no reason a 50k truck should chirp like a POS when driving around the city.

I have also noticed, if the truck happens to go from 4cyl to 8cyl at around 20-30mph and you happen to be slowing down between a 3-2 downshift.... make sure your seatbelt is on! the combo of the valve sticking closed, causing the backpressure go up in 8cyl and the downshift will damn near throw you through the windshield. I have read GM is doing some fancy stuff with the torque converter and doing some engine braking through the locked converter during a decel to help save the "lifetime" brake pads. not sure what is exactly happening, but whatever concoction of things happens makes if very unpleasent to drive

With that being said, i dont think we should have to clamp open a valve. GM put it there for a reason, and im sure that was not to squeak...

2014 SIlverado 5.3L Z71

fondupot · December 16, 2014

Have the same issue. have been battling with the dealership about this. Im not comfortable with them clamping it open since its a lease truck. That valve (IMO) creates higher backpressure for the engine when you are in 4 cylnider mode. the chirp comes from when the valve opens back up.

GM has replaced my muffler once and it came right back. It gets louder over time also. They have been tying to talk with TAC about this and find a fix.

I just got off the phone with my laywer about this and he is wanting to look into a lemon-law or customer compensation case for loss of vehicle value. Not sure I want to take it that far, but ther is no reason a 50k truck should chirp like a POS when driving around the city.

I have also noticed, if the truck happens to go from 4cyl to 8cyl at around 20-30mph and you happen to be slowing down between a 3-2 downshift.... make sure your seatbelt is on! the combo of the valve sticking closed, causing the backpressure go up in 8cyl and the downshift will damn near throw you through the windshield. I have read GM is doing some fancy stuff with the torque converter and doing some engine braking through the locked converter during a decel to help save the "lifetime" brake pads. not sure what is exactly happening, but whatever concoction of things happens makes if very unpleasent to drive

With that being said, i dont think we should have to clamp open a valve. GM put it there for a reason, and im sure that was not to squeak...

2014 SIlverado 5.3L Z71

Dude just clamp the valve open. My truck is leased to. As long as you remove it when you go to trade it in.

bladz1454 · December 16, 2014

I feel like im the only person that liked that sound. I would be driving along at like 20-30mph and when i gave it gas, I thought that chirp from the exhaust sounds like a blow off valve haha, I kind of enjoyed it.

dcoates01 · December 17, 2014

I feel like im the only person that liked that sound. I would be driving along at like 20-30mph and when i gave it gas, I thought that chirp from the exhaust sounds like a blow off valve haha, I kind of enjoyed it.

Nah..... you want blow off valve sound boost it.... haha.

dcoates01 · December 17, 2014

Dude just clamp the valve open. My truck is leased to. As long as you remove it when you go to trade it in.

Thats probably what I will do. not to noticable in the winter with the windows up, just pisses me off ya know?

just dont want to be mistaken for "bub rub or Lil Sis" and have people think I installed some whistle tips

Whhoo whhhhoooooooooooooooo!!!!!

Mthornton1 · December 30, 2014

My truck has done this since day 1. I have taken it to dealer. They say there is no fix for it. How do I clamp the flapper valve to get it to stop? Any answers will help. Thanks!