GF47.30-P-3015MIS Purging Function
GF47.30-P-3015MIS Purging Function
- MODEL 221.0 /1 with ENGINE 272.9 as of model year 2009 /YoM 08
- MODEL 216.3, 221.0 /1 with ENGINE 273.9 as of model year 2009 /YoM 08
Schematic diagram of fuel tank aeration and ventilation
1 Activated charcoal canister chamber 1
2 Activated charcoal canister chamber 2 (with CODE (494) USA version)
3 Activated charcoal canister chamber 3 (with CODE (494) USA version)
45 Fuel filler neck
45/1 Refueling ventilation
45/2 Float with flap
58 Fluid reservoir
75 Fuel tank
75/1 Safety valve (rollover valve)
75/2 Fuel retention valve
77 Activated charcoal canister
B4/3 Tank pressure sensor (with Code (494) USA version)
Y58/1 Purge control valve
Y58/4 Activated charcoal filter shutoff valve (with Code (494) USA version)
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
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 O2 sensors upstream of ME-SFI [ME] control unit(G3/3, G3/4), oxygen sensor signals
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-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.
