Exhaust Flap Damper Control (M54 - if equipped)
To meet European noise level compliance, the rear silencer incorporates a flap that is designed to reduce exhaust noise at idle, low RPM acceleration and while coasting. Components of the system include:
- Exhaust Flap with Vacuum Actuator
- Switching Solenoid
- Vacuum Reservoir
The ECM will power the switching solenoid and apply vacuum to the exhaust flap actuator to close the flap allowing additional damping of the exhaust.
The ECM will deactivate the solenoid when accelerating above 2500 RPM (approx.) under load. The vacuum is vented from the flap actuator and the flap opens. This decreases the exhaust backpressure for improved torque and acceleration.