Intake manifold switchover, function - GF07.10-P-1017MI

ENGINE 272.9 (except 272.982) in MODEL 204.0/2 as of model year 2009

ENGINE 272.9 (except 272.983) in MODEL 212

ENGINE 272.9 (except 272.984) in MODEL 207

ENGINE 272.9 in MODEL 204.9

ENGINE 273.9 in MODEL 207, 212

Function requirements for intake manifold switchover, general points

Circuit 87M ON (engine timing ON)
Engine running

Intake manifold switchover, general points

The intake manifold switchover is used to switch between the long and short intake tracts. This optimizes the engine torque.

The ME-SFI [ME] control unit (N3/10) actuates the intake manifold switchover according to the signals from the following sensors:

hot film MAF sensor (B2/5), engine load
crankshaft Hall sensor (B70), engine speed

Function sequence for intake manifold switchover

For the intake manifold switchover, the ME-SFI [ME] control unit uses a ground signal to actuate the intake manifold switchover valve (Y22/6), according to engine load and engine speed.

Engine 272

The variable length intake manifold switchover flaps for a cylinder bank are linked to each other by a spindle and are each actuated by a vacuum unit.

The vacuum units are connected by hose lines to the intake manifold switchover valve.

When the intake manifold switchover valve is not actuated, the vacuum units are ventilated and the switchover flaps are opened by spring force.

Air intake takes place over the short intake tracts.

When the intake manifold switchover valve is actuated, the vacuum units are charged with vacuum from the vacuum reservoir. This causes the switchover flaps to close, and air is admitted through the long intake tract.

Engine 273

The switchover flaps for each cylinder bank are linked to each other by means of a shaft. The two shafts are joined by a linkage and are actuated together by a vacuum unit.

The vacuum unit is connected to the intake manifold switchover valve by a hose line.

When the intake manifold switchover valve is not actuated, the vacuum unit is ventilated and the switchover flaps are opened by spring force. Air intake takes place over the short intake tracts.

When the switchover valve is actuated, the vacuum unit is charged with vacuum from the vacuum reservoir. This causes the switchover flaps to close, and air is admitted through the long intake tract.

The variable length intake manifold switchover flaps are opened in the following conditions:

relative engine load <50%
engine rpm <2000 rpm or >3500 rpm

Air intake takes place over the short intake tracts. In this way an increase in engine torque and output is achieved.

Short intake tracts (section in cylinder level)

Fig 1: Intake Manifold Flow Diagram (Flap Open)

Courtesy of MERCEDES-BENZ USA

The variable length intake manifold switchover flaps are closed in the following conditions:

relative engine load >80%
engine speed approx. 2000 to 3500 rpm

Air intake takes place over the long intake tracts. In this way an increase in engine torque and output is achieved.

Long intake tracts (section in cylinder level)

Fig 2: Intake Manifold Flow Diagram (Flap Closed)

Courtesy of MERCEDES-BENZ USA

Electrical function schematic for intake manifold switchover	MODEL 204	PE07.10-P-2717-97FAB
	MODEL 207	PE07.10-P-2717-97EAB
	MODEL 212	PE07.10-P-2717-97DAB
Overview of system components motor electronics (ME-SFI) fuel injection and ignition system		GF07.61-P-9997MI