Evaporative emission system
Evaporative emission system |
Function |
The fuel vapour from the fuel tank breather system is led to a evaporative emission (EVAP) canister filled with activated charcoal and is stored in the activated charcoal when the engine is switched off.
When the car is running the fuel vapour is sucked into the engine through the EVAP canister purge valve.
The EVAP canister purge valve is controlled by the engine control module which, by taking the engine's working load etc .into consideration, decides when the engine can burn this additional fuel.
From the outlet the vapour is led via a hose to the intake manifold where it is burnt together with the ordinary fuel-air mixture.
Evaporative emission canister |
The evaporative emission canister consists of a container filled with activated charcoal. The function of the EVAP canister is to act as an "intermediate storage" for fuel vapour from the tank. The cover of the canister contains connections for an inlet from the tank and an outlet via a EVAP canister purge valve. In addition there are also openings for fresh air. Air is sucked through these openings, via the charcoal for purification, into the intake manifold.
Diagnosis and fault-tracing |
Diagnosis and fault-tracing of the EVAP canister purge valve are dealt with in Service Manual 2.7 "Engine Management System".