GF47.30-P-3015MI Purging Function

GF47.30-P-3015MI Purging Function
- MODEL 204.0 /2 with ENGINE 272.9 (except 272.98) as of model year 2009 /AEJ 08
- MODEL 204.9, 207.3 /4, 212.0 /2 with ENGINE 272.9 (except 272.98)
- MODEL 207.3 /4, 212.0 /2 with ENGINE 273.9





Schematic diagram (except code (494) USA version)
45 Fuel filler neck
58 Fluid reservoir
75 Fuel tank
75/1 Fueling, limiting and vent valve
75/2 Breather valve
77 Activated charcoal filter
Y58/1 Purge control valve
A Air admission line and vent line
B Purge line

Purging function requirements, general
- Circuit 87M ON (engine control ON)
- Engine started for at least 45 s
- Coolant temperature greater than 40°C
- Engine not in deceleration mode
- Engine not in the lambda adaptation phase

Purging, general points
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 [ME] control unit (N3/10) reads the following sensors:
- Hot film MAF sensor (B2/5), engine load
- Intake air temperature sensor (B2/5b1)
- Coolant temperature sensor (B11/4)
- Crankshaft Hall sensor (B70), engine speed
- LH and RH oxygen sensors upstream of catalytic converter (G3/3, G3/4)

Function sequence for purging
The fuel tank is ventilated through the aeration/vent valves, the aeration/vent line and the activated charcoal canister.
The fuel vapors flow to the activated charcoal canister where 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 and combusted in the engine.

To control the purge quantity, the ME-SFI [ME] 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-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 leaned out according to the level of fuel vapor charge in the activated charcoal canister.