Purge function - GF47.30-P-3015MAS
MODEL 216.377, 221.077/177 with ENGINE 156.984 as of Model Year 09/AEJ 08
Schematic diagram of fuel tank aeration and ventilation
Purging function requirements, general
- Circuit 87M ON (engine control ON)
- Engine started for at least 45 s
- Coolant temperature > 40°C
- Engine not in deceleration mode
- Engine not in the lambda adaptation phase
Purging, general
When the fuel tank is being ventilated, no fuel vapors should escape into the outside air.
The fuel vapors are stored in the activated charcoal canister and burnt later in the engine.
In order to enable the purging, the ME-SFI control unit (N3/10) reads the following sensors:
- LH and RH hot film MAF sensor (B2/6, B2/7), engine load
- Coolant temperature sensor (B11/4)
- Intake air temperature sensor (B17)
- Crankshaft Hall sensor (B70), motor speed
- LH and RH O2 sensors upstream of CAT (G3/3, G3/4)
Purging function sequence
The fuel tank is ventilated through the safety valves (rollover valves), the fuel retention valve and the activated charcoal canister.
The fuel vapors flow to the activated charcoal canister where they are stored, and drawn off into the variable intake manifold when purging is enabled.
When the engine is running, the fuel vapors stored in the activated charcoal canister, are drawn off through the purge control valve (Y58/1) and combusted in the engine.
To control the purge quantity, the ME-SFI control unit actuates the purging switchover valve at the ground end with a pulse width modulated signal (PWM signal) (with a frequency of 10 Hz). The purge quantity is determined by continuously opening and closing the purge control valve with on-periods of varying durations.
The idle speed control prevents the purging from causing a change in rpm when the engine is at idle. The fuel-air mixture is leaned out according to the level of fuel vapor charge in the activated charcoal canister.
| Electrical function diagram for purging function | Model 216 | PE47.30-P-2052-97CAC |
| Model 221 | PE47.30-P-2052-97SAC | |
| ME-SFI [ME] control unit, component description | N3/10 | GF07.61-P-6000MAS |