Engine code BBW: Notes

Depending on air pressure and ambient temperature, fuel vapor will form above the level of fuel in the tank.

The EVAP system prevents these hydrocarbon emissions from escaping into the atmosphere.

The fuel vapors of the fuel tank flow via the internal bubble canister in the fuel tank, through the integrated gravity valve, into the EVAP canister.

The activated charcoal in the EVAP canister stores these vapors like a sponge.

When the oxygen sensor control is active during driving (engine warm), the EVAP canister purge regulator valve -N80- is activated (pulsed) from engine control module depending upon load and engine speed. The opening period is dependent on the input signals.

The intake manifold vacuum draws fresh air through the breather opening on the underside of the EVAP canister during the purging procedure (regenerating the activated charcoal). The fuel vapors stored in the activated charcoal and fresh air are fed for combustion in dosed quantities via the EVAP canister purge regulator valve -N80-.

When no voltage is applied (e.g. wiring open circuit), the solenoid valve is closed. The activated charcoal canister will not be purged.

The vacuum line from the throttle valve control module to the EVAP canister has an additional by-pass which is connected with the crankcase breather valve. The non-return valve integrated in the crankcase breather valve prevents the intake air gassing into the crankcase during some partial load ranges. This improves the overall crankcase breathing. The by-pass guarantees the crankcase breathing.