6.2L exhaust sound when stopping

[Dustindu4]

When rolling to a stop, my exhaust note changes when stopping. It almost sounds like an exhaust leak. Is that the stupid valve before the muffler opening and closing? Am I nuts?

 

[wendal]

This is dynamic fuel management cutting out cylinders as the vehicle slows to a stop.

 

[GMCnewbee]

I do not notice anything like that with my 2022 Denali. Does it have cylinder deactivation? I have never noticed it on the highway or when driving around.

 

[wendal]

Yes, it has cylinder deactivation. Trust me... You have a hard time hearing it because your muffler has flaps both before and after the muffler. I have a new exhaust system, and the change in number of cylinders is much more pronounced, particularly when slowing down.

 

[wendal]

Yes, it has cylinder deactivation. Trust me... You have a hard time hearing it because your muffler has flaps both before and after the muffler. I have a new exhaust system, and the change in number of cylinders is much more pronounced, particularly when slowing down.

Correction: Flap before muffler, resonators at the exhaust tips. Had to go back and look at my pictures.

 

[GMCnewbee]

Thanks for the info. I have to say that I really never notice it and I an very tuned into my machines. The engineers did a good job on that one. It really is seamless, at least for now.

 

[JacquesMehoff]

Mine makes a chirping sound when coming to a stop. Is that the sound you’re hearing? I tried pinning the flapper open and still hear it. Noticed it goes away when using L9.

 

[Garth Knight]

Can't you just disable the DFM system? Plus with all the bent rods etc maybe it's best to not use this feature.

 

[wendal]

Can't you just disable the DFM system? Plus with all the bent rods etc maybe it's best to not use this feature.

On the 21's and up, there is nothing to disable the DFM. The ECM is locked down apparently. Driving in L9 is the only method I am aware of, and I've been researching for over a year now.

 

[Garth Knight]

Wendal,

I had watched a video recently about someone disabling the DFM via some added computer mod. I'll have to double check and give you the link if it's what I remember it being.