Intake manifold switchover, function - GF07.61-P-3028MAS

ENGINE 156.984 in MODEL 216.377, 221.077 /177 as of Model Year 09 /AEJ 08 

Function requirements for intake manifold switchover, general points 

• Circuit 87M ON (engine control ON)
• Engine running

Intake manifold switchover, general points 

The intake manifold switchover is used to switch between the long and short intake tracts. In this way the engine torque is optimized.

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

• LH and RH hot film MAF sensor (B2/6, B2/7), engine load
• Crankshaft Hall sensor (B70), motor speed

Intake manifold switchover function sequence 

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

The switchover flaps are operated by the variable intake manifold vacuum unit by means of a linkage.

The vacuum unit is linked to the variable 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.

Switchover flaps open (Cross-section at cylinder level) 

At low rpm and low load, or at high rpm, the variable intake manifold switches to the short intake tract. The short intake tract allows the engine to reach high rpm.

Switchover flaps closed (Cross-section at cylinder level) 

The variable intake manifold ensures a full torque curve at low rpm and high load.

	Electrical function schematic for intake manifold switchover	Model 216	PE07.61-P-2781-97CAC
		Model 221	PE07.61-P-2781-97SAC
	ME-SFI [ME] control unit, component description	N3/10	GF07.61-P-6000MAS