Evaporative Purge System Monitoring

GENERAL DESCRIPTION

EVAP. FAMILY XBMXE0156E36

The evaporative system monitoring permits the detection of leaks in the evaporative emission control system with a diameter of 1 mm and up.

The evaporative emission control system is hermetically sealed off from the atmosphere by means of a shut-off valve at the charcoal canister. When the purge valve opens, the engine generates a vacuum in the tank. After closing the purge valve the pressure increase is measured by a tank pressure sensor. If the vacuum increases above a defined threshold a leak is detected.

As part of the vacuum check the purge flow is verified.

MONITORING STRUCTURE

The following conditions must be fulfilled to start the monitoring procedure.

No malfunction:
- in detecting battery voltage
- in detecting vehicle speed
- in detecting the air mass meter
- in detecting coolant temperature
- in detecting the purge valve signal
- in detecting the throttle valve position sensor
- in detecting the idle speed control valve
- in detecting the shut off valve signal
- of misfire detection
- of the tank pressure sensor
- of the secondary air system





Monitoring while car running





Evaporative System Monitoring Structure





Test for vapor generation





Evaporative system diagnosis





OBD-II Evaporative System
leak check - fuel tank pressure diagram





OBD-II Evaporative System