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

ENGINE 276.9 in MODEL 204, 207, 212 (except 212.095), 218 

Function requirements for intake manifold switchover, general points 

Intake manifold switchover, general points 

The air ducting and the length of the intake tracts are altered with the intake manifold switchover by means of a selector drum and two resonance flaps. The RH and LH side of the intake manifold are also connected together over a resonance chamber. Based on these measures, development of the engine torque is optimized by the so-called "internal charging". To do this the kinetic energy in the air flowing in the intake tract and the vibrations of the air columns are used. The length of the intake manifold can be altered for "inner charging" over a wide RPM range. The length is altered by the resonance flaps (variable-geometry intake manifold).

In the lower RPM range the air flows through the long intake tract. The short intake tracts are closed by the resonance flaps and the selector drum. At high rotational speeds the resonance flaps and the selector drum are opened. The length of the intake tracts are therefore adapted to the high gas change frequency and the short intake tracts allow a higher gas flow.

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

Function sequence for intake manifold switchover 

The intake manifold switchover is differentiated into two subsystems:

Function sequence for selector drum switchover 

In order to switch over the selector drum the intake manifold selector drum switchover valve (Y77/3) is actuated by means of a ground the ME-SFI [ME] control unit, dependent on the engine load and engine speed.

The selector drum vacuum unit is linked to the intake manifold switchover valve by a hose line. Without actuation of the intake manifold switchover valve, the selector drum vacuum unit is ventilated and the selector drum is turned by means of spring force in the open position. The intake air can flow through the selector drum to the rear in the RH and LH intake area of the intake manifold.

The selector drum vacuum unit has vacuum applied to it from the vacuum pump for actuation of the intake manifold selector drum switchover valve. In this way the selector drum is turned by about 90° and closes the rear intake tracts of the intake manifold. The air intake in the intake manifold only takes place over the front intake tracts.

High RPM range 

The selector drum opens under the following circumstances:

Medium RPM range 

The selector drum closes under the following circumstances:

Lower range of rotational speeds 

The selector drum closes under the following circumstances:

Function sequence for resonance flaps switchover 

In order to open the resonance flaps the intake manifold selector drum switchover valves (Y77/2) are actuated in parallel by means of a ground signal by the ME-SFI [ME] control unit, dependent on the engine load and engine speed.

The resonance flap vacuum units are connected over the hose lines with the intake manifold selector drum switchover valves. Without actuation of the intake manifold selector drum switchover valves the resonance flap vacuum units are ventilated and the resonance flaps are closed by spring force. The resonance chamber is closed off. In order to actuate the intake manifold selector drum switchover valves the resonance flap vacuum units have vacuum applied to them from the vacuum pump and the resonance flaps are opened. The intake air can flow over the resonance chamber between the RH and LH intake area of the intake manifold.

High RPM range 

The resonance flaps are opened under the following conditions:

Medium RPM range 

The resonance flaps are opened under the following conditions:

Lower range of rotational speeds 

The resonance flaps are closed under the following conditions:

IMPORTANT In the failure position the resonance flaps are closed and the selector drum is opened over the whole range of rotational speeds.

Phantom view of the intake manifold 

Fig 1: Intake Manifold Switchover Function Diagram
G10049939Courtesy of MERCEDES-BENZ USA
  Electrical function schematic for intake manifold switchover MODEL 204 PE07.10-P-2717-97FAK
MODEL 207 PE07.10-P-2717-97EAH
MODEL 212 PE07.10-P-2717-97DAI
Model 218 PE07.10-P-2717-97XAB
  Overview of system components for gasoline injection and ignition system with direct injection ENGINE 276.9 in MODEL 204, 207, 212 (except 212.095), 218 GF07.70-P-9998MM
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