Actuation divert air, function - GF09.40-P-3002M

ENGINE 275.950 in MODEL 215, 220

ENGINE 275.951 in MODEL 230 up to Model Year 8

ENGINE 275.953 in MODEL 216, 221 up to Model Year 8

ENGINE 275.954 in MODEL 230 up to Model Year 8

ENGINE 275.980 in MODEL 215, 220

ENGINE 275.981 in MODEL 230 up to Model Year 8

ENGINE 275.982 in MODEL 216, 221 up to Model Year 8

ENGINE 285.950 in MODEL 240

ENGINE 285.980 in MODEL 240

Fig 1: Actuation Divert Air Function Diagram

Courtesy of MERCEDES-BENZ USA

Fig 2: Identifying Vacuum Reservoir

Courtesy of MERCEDES-BENZ USA

Fig 3: Identifying Charge Air Cooler, Right Cylinder Bank And Test Connection For Divert Air

Courtesy of MERCEDES-BENZ USA

Function

If the engine control unit identifies the transition from load to deceleration operation, the switchover valve deceleration switchover (Y101) is actuated. Through this both deceleration air valves at the turbochargers are discharged with vacuum from the vacuum tank (22). The deceleration air valves open a bypass around the individual compressor turbine wheel, through which the boost pressure is immediately removed. Charger noises (brief howling) during transition into the deceleration mode cannot result from pressure points in the charger.

The turbochargers rotate a little, by means of the inertia of masses of shaft, the compressor and the turbine wheel after start of deceleration and create against the closed throttle valve briefly further boost pressure. This pressure is quickly released through the deceleration air valves.

Without actuation at the switchover valve deceleration switchover the diaphragm chambers of the deceleration air valves are connected with the intake manifold. The deceleration air valves close in load operation through the boost pressure and the spring load. If a deceleration air valve does not close, less boost pressure is released.

In the vacuum tank vacuum is gathered in the suction operation of the engine and in the deceleration. The check valve opens only at vacuum.

	ME-SFI control unit, location/task/design/function		GF07.61-P-5000M
	Accelerator pedal sensor, location/task/design/function		GF30.20-P-4010M
	Divert air switchover valve location/task/structure/function		GF07.05-P-3104M
	Turbocharger, location/task/function		GF09.40-P-3100M
	ME-SFI pneumatic diagrams		PP07.61-P-5000M