Active Exhaust System (Supercharger Vehicles Only)

The position of the exhaust valves set by the engine control module (ECM) depends on engine speed, throttle angle and operating mode of the transmission. At startup the exhaust valves are always open, to enhance the exhaust sound.

When the transmission is in the manual (sequential shift) mode, the exhaust valves are permanently open. When the transmission is in the normal or sport mode, the position of the exhaust valves depends on engine speed and load, as detailed in the following table:

Exhaust Valve Opening Strategy (Normal and Sport Transmission Modes) 

The engine control module (ECM) energizes the active exhaust relay in the auxiliary junction box (AJB) 5 seconds after the ignition is switched on. When the relay is energized, it supplies power to the vacuum pump and the solenoid valve. The vacuum pump is connected to ground and runs continuously while the relay is energized, maintaining a depression in the reservoir and pipes to the solenoid valve.

The solenoid valve is connected to ground through the engine control module (ECM). When the engine control module (ECM) determines the exhaust valves require closing, it connects the solenoid valve to ground. When the solenoid valve energizes, it opens the pipe connection from the reservoir and vacuum pump to the exhaust valves, and closes the atmospheric vent. The depression at the reservoir and vacuum pump is then sensed at the exhaust valves, via the check valve, and the exhaust valves close. When the engine control module (ECM) determines the exhaust valves require opening, it disconnects the solenoid valve from ground. The solenoid valve de-energizes and closes the pipe connection to the exhaust valves, and opens the atmospheric vent. Atmospheric pressure is then sensed at the exhaust valves, via the restrictor, and the exhaust valves open.

Active Exhaust System Schematic

Courtesy of JAGUAR CARS, INC.