2021 Sierra Denali 6.2L Engine or Exhaust Chirp Noise

[Pbrad074]

Hi All,

 

I’m new here and I love all the information in the forums. 
 

I recently purchased a new 2021 Denali with 6.2L that had factory installed cat back exhaust installed. I noticed a loud chirping noise on cold start-up, while in park with low revs 1000-1100 rpm and then goes away and finally when coming to a stop when the transmission second to first gear. 
 

I have brought it to the dealer and they can’t figure out what the noise is and have taken the exhaust apart reinstalled with new gaskets and the chirp is still there. 
 

I don’t know if it is a back pressure issue or the performance exhaust itself.
 

I have attached a picture of the tag on the muffler to see if anyone knows who manufactures the exhaust system (borla or corsa) and if anyone has experience the same chirping noise. 
 

thanks in advance. 
 

Peter

Edited July 6, 2021 by Pbrad074

[bbmxta]

You sure that chirp isn't coming from the front of the engine?  A lot of people, including myself, have that annoying chirp/squeak coming from the front of the engine.  I have a 2020 Chevy RST w/ 6.2 and it chirps pretty much every startup after sitting even for a little bit then goes away

[Lobe50]

My 2020 RST 6.2L Also has this chirping sound, anyone else find any cause/answer?

Thanks

[Pbrad074]

Update:

 

With much negotiation, I’m bringing the truck back to the dealer this week to have the muffler replaced. 
 

I will report back once installed. 

[Lobe50]

From what I can see the noise is not coming from the exhaust it's coming from the engine on mine. And just added information it had a Gibson muffler on it when I bought it and was making the noise and I installed the muffler delete 2 days ago and the noise still exists.

[Pbrad074]

Thanks for the update - I guess the muffler replacement won’t help me then…. I will keep looking. 

 

My truck will also chirp coming to a stop when the trans down shifts from 2nd to 1st. Are you able to reproduce the chirp at low rev up, 800-900rpm in park?

[It's Tim]

Engine mount.

[Lobe50]

My me maybe be different...it's more of an idling issue. Obviously more apparent in the garage. I'll try spraying the serpentine belt. I'm guessing that may help.

[RBowser]

My new 21 Silverado 6.2 has the same problem. I noticed it the next day after I bought it. Started it in the garage to go to work the next morning. Chirpy chirp chirp. Sounds like serpentine belt chirp. It doesn't go away until it's completely warmed up but I swear I can hear it all the time after the first time I heard it especially at light throttle when it feels like its misfiring from the cylinder deactivation. Sounds like its coming from the left side of the engine to me. I do not think its belt noise. I watched a bunch of exhaust videos on YouTube (because I'm debating what catback I want) and I heard the same noise in a bunch of them. I read somewhere that it may be the lifters due to the cylinder deactivation. I'm just going to deal with it until it bends a pushrod. its under warranty

[American Cobra]

This has been talked about / debated on here in many threads.  Its the DFM on the 6.2 engines.  Trying putting yours in L9 and drive around (this turns off DFM).  You wont hear the noise anymore.  There is no fix that I know of except for purchasing the Pulsar LT module for $500 to shut off DFM.

[Pbrad074]

Thanks for the update - And pardon my ignorance, but what is L9?

 

 

[OnTheReel]

1 hour ago, Pbrad074 said:

Thanks for the update - And pardon my ignorance, but what is L9?

 

 

Put the trans in low, and manually click the (+) on the shifter until it’s in “L9” (indicated on the DIC). It will shift normally and automatically, but 10th gear will be locked out and and DFM will not be active in any gear.
 

Probably a moot point because DFM is not active at idle / in park. I’ve read some things suggesting it’s the cat and that makes sense because mine doesn’t squeak once warmed up. Nothing to really worry about.

[Pbrad074]

I tried putting it in L9 and it worked…..chirp is gone!!!

 

thank you!!!!

[rsimons]

I have the exact same issue on my 2021 Denali 6.2L.  I do not have the performance exhaust option.  Dealer first told me it was the butterflies in the exhaust and that it was normal.  I then installed a Magnaflow exhaust that eliminates them. Still makes the noise.  Brought it back to the dealer, and they said they drove another truck and it makes the same noise so it's normal, but couldn't tell me what it was.  I called GM customer service, and have been going back and forth with them for almost 3 months. They finally told me to make an appointment with the service manager to drive a similar, new, vehicle and see if it makes the noise.  3 weeks of trying to get in touch with the service manager and still no calls back.  The noise is really annoying. 

[rsimons]

Quick follow up.  I just tried the L9 mode and confirmed that it stops the noise while driving (decel).  Of course this doesn't help on cold start while in Park.  Can anyone confirm if the Pulsar LT (DFM deactivation) will help at start up?