Crankcase Ventilation System, Function - GF01.20-S-0001TRC
Engine 274 in model 447, 448
except code XM0 (Facelift)
Function requirements for crankcase ventilation system, general
- Circuit 87M ON (Engine management ON)
The circuit 87 signal is sent by the circuit relay 87M over direct line to the ME-SFI [ME] control unit (N3/34).
Crankcase ventilation system, general
The crankcase ventilation system ensures under all operating conditions of the engine that overpressure and excess gases are dissipated from the crankcase and fed back to the engine via the intake air system for combustion. To balance out the pressure ratio, a separate line is attached for engine ventilation (3).
Crankcase ventilation system controlling is dependent on the following components and signals:
- Intake manifold pressure sensor (B28/24), engine load signal over a direct line to the ME-SFI [ME] control unit (N3/34)
- Accelerator pedal module (B37/4), accelerator pedal position signal over a direct line to the ME-SFI [ME] control unit
- Signal acquisition and actuation module (SAM) control unit (N10/1), outside temperature from outside temperature sensor (B14) via interior CAN (CAN B), electronic ignition lock control unit (EZS) (N73) and chassis CAN (CAN E)
- Vent line contact switch (S208), vent line signal over direct line to the ME-SFI [ME] control unit
Crankcase ventilation system function sequence
The function sequence of the crankcase ventilation system is described in the following points:
- Function sequence for crankcase ventilation system partial load operation
- Function sequence for crankcase ventilation system wide open throttle operation
Function sequence for crankcase ventilation system partial load operation
In partial-load range, ventilation is performed starting from the oil separator (2) to the charge air distributor. To do so, the partial load operation crankcase ventilation system valve (Y136) is arranged in the partial-load vent line (A).
The partial load operation crankcase ventilation system valve (Y136) is actuated in deceleration mode by the ME-SFI [ME] control unit and closes the partial-load vent line (A) from the crankcase to the charge air distributor.
The inflow of exhaust from the crankcase during the mixture adaptation and disruptive background noise are thus avoided. If there is no actuation by the ME-SFI [ME] control unit, the partial load operation crankcase ventilation system valve (Y136) is permanently open.
Function sequence for crankcase ventilation system wide open throttle operation
In wide open throttle operation, ventilation is performed starting from the oil separator (2) to the air intake pipe.
The wide open throttle operation vent line heater element (B) is located in the vent line heater element wide open throttle operation (B157) and prevents freezing of the ventilation system. To do so, the vent line heater element wide open throttle operation (B157) is actuated directly by the ME-SFI [ME] control unit as soon as outside temperatures of under 7°C are measured.
View of engine from front left
| Electrical function schematic for crankcase ventilation system | Engine 274 in model 448 except code XM0 (Facelift) | PE01.20-S-2001-97VDC | |
| Engine 274 in model 447 except code XM0 (Facelift) | PE01.20-S-2001-97TRC | ||
| Overview of system components for gasoline injection and ignition system with direct injection | GF07.70-S-9998TRC |