What is the bulletin number for the exhaust replacement? Has anyone else on the forum other than Leslie had this done? Strange that it would solve the vibration problem, only to have it return later..
PIT5404C (should be on revision C now)
This is not a ride quality vibration were discussing here. These are harmonic vibrations that introduce buffeting and booming into the cab.
The exhaust V4 AFM flapper on the 5.3 adjust and changes the back pressure of the exhaust to compensate for the lower combustion of 4 cylinders versus 8.
This back pressure drone, causes a harmonic vibration which introduces the buffeting.
This is additional buffeting above and beyond the RFB vibration which also causes buffeting.
Replacing the exhaust, does nothing because the AFM will continue to change the V4 v8 management, changing the back pressure, changing the drone, causing the buffeting.
The only way to stop this form of buffeting is driving with the AFM off.
See the PIT...Once of the diagnostics is switch the AFM off and seeing if the buffeting persists.
If the buffeting goes away, it a normal function of the vehicle cause by AFM.
This does not apply to the 6.2 because of the Bose ANC.