Purging System
TASKChecking the evaporative emission control system for function of the components and leakages.
FUNCTION
The check of the evaporative emission control system is carried out if the following conditions are met simultaneously:
- No fault in electrical actuation of purge control valves
- Actuation of purge control valves with an ON/OFF ratio between about 40-60%.
If all the conditions are met, the ME-SFI control module detects the pressure in the pipe from the activated charcoal filter to the purge control valves from the purge monitoring pressure sensor (B4/4).
The pressure pattern in the pipe varies in accordance with the pulsed actuation of the purge control valves.
The ME-SFI control module monitors these variations in pressure for about 4s. If the pressure levels are less than about 50 bar apart, a fault is detected.
At higher elevations an altitude correction is conducted (e.g. pressure variations of about 11 bar are permissible at more than 2400 meters).