@Z7122 , what is the DFM that you're referring to? I tried L9, and like you, the noise disappears. I am by no means well versed in the technical or mechanical aspects here. I'm struggling to understand why the injectors would make the noise in Drive, but not in L mode. Also trying to figure out how to make the dealer understand and agree to diagnose and correct it.
@Doubeleive , I don't know what made me ask if it would shift through the gears normally. I guess because I had never tried L mode on this vehicle. It was a stupid question, LOL.
In older models going back to the 6 speed I believe, tow/haul or M5 disables the AFM on earlier models and it seems that M9 will disable DFM on 21+.
If the noise goes away when in L9 and not in D and the noise is most likely associated with the DFM system. This system shuts off cylinders at will and can run on any combination of the 8 cylinders because all of them are setup this way.