Purging Function - GF47.30-S-3015TRC
Engine 274 in model 447, 448
Purging function requirements, general points
- Engine started for at least 45 s
- Coolant temperature > 45°C
- Engine not in overrun mode
- Engine not in the lambda adaptation phase
Purging general points
When the fuel tank (3) is being ventilated no fuel vapors should escape into the outside air The fuel vapors are stored in the activated charcoal canister (1) and burnt later in the engine.
In order to enable the purging the ME-SFI [ME] control unit (N3/34) directly reads in signals from the following sensors over direct line:
- Purging pressure sensor (B158)
- Coolant temperature sensor (B11/21)
- Charge air temperature sensor upstream of throttle valve (B17)
- Charge air temperature sensor downstream of throttle valve (B17/16)
- Intake manifold pressure sensor (B28/24)
- Crankshaft Hall sensor (B70/2)
- Oxygen sensor element downstream of catalytic converter (G3/21b1)
- Oxygen sensor element upstream of catalytic converter (G8/6b1)
Function sequence for purging
Aeration and ventilation of the fuel tank (3) takes pace over the aeration and bleed valves (4) the aeration and vent lines (5) and the activated charcoal canister (1)
If all function requirements for purging are fulfilled the fuel vapors stored in the activated charcoal canister (1) are suctioned off over the purging switchover valve (Y58/7) and the purge line (6) and burnt in the engine.
To control the purge quantity the ME-SFI [ME] control unit (N3/34) actuates the purging switchover valve (Y58/7) at the ground end with a pulse width modulated signal at a frequency of 10 to 30 Hz.
The purge quantity is determined by continuously opening and closing the purging switchover valve (Y58/7) with on-times of varying duration.
The idle speed control prevents the purging from causing a change in rpm when the engine is at idle The fuel/air mixture is made lean appropriately dependent on the fill level of the activated charcoal canister (1)
| Electrical function schematic for purge control | Engine 274 in model 447 except code XM0 (Facelift) | PE47.30-S-2052-97TRC | |
| Function schematic for purging | Engine 274 in model 447.8, 448 with code XM0 (Facelift) | PE47.30-S-2500-97TRI | |
| Engine 274 in model 447.6/7 with code XM0 (Facelift) | PE47.30-S-2500-97TRH | ||
| Overview of system components for gasoline injection and ignition system with direct injection | Engine 274 in model 447, 448 except code XM0 (Facelift) | GF07.70-S-9998TRC | |
| Engine 274 in model 447.6/7 with code XM0 (Facelift) | GF07.70-S-9998TRJ |