Intake Manifold Switchover, Function - GF07.10-P-1017MMG
ENGINE 276.9 in MODEL 166 up to model year 2016
Function requirements for intake manifold switchover, general points
- Circuit 87M (engine management ON)
- Engine runs
Intake manifold switchover, general points
The length of the intake tract is altered with the intake manifold switchover by means of a selector drum.
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 air system and the vibrations of the air columns are used. "Charging" over a wide range of rotational speeds can be achieved by altering the length of the intake manifold. The length is altered by the resonance flaps.
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:
- Pressure sensor downstream of throttle valve (B28/7), engine load
- Crankshaft Hall sensor (B70), engine rpm
Intake manifold switchover function sequence
The intake manifold switchover is differentiated into two subsystems:
- Function sequence for selector drum switchover
- Function sequence for resonance flaps switchover
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 vacuum unit selector drum is linked to the intake manifold selector drum switchover valve by a hose line.
Without actuation of the intake manifold selector drum 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:
- Engine load > 50%
- Engine speed > 4250 rpm
Medium rpm range
The selector drum closes under the following circumstances:
- Engine load > 50%
- Engine speed > 3200 to 4250 rpm
Lower range of rotational speeds
The selector drum closes under the following circumstances:
- Engine load > 50%
- Engine speed < 3200 rpm
Function sequence for resonance flaps switchover
In order to open the resonance flaps the intake manifold resonance flap 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 resonance flap switchover valves.
Without actuation of the intake manifold resonance flap 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 resonance flap 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.
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
| Electrical function schematic for intake manifold switchover | PE07.10-P-2717-97NAE | ||
| Overview of system components for gasoline injection and ignition system with direct injection | GF07.70-P-9998MMG |