Volkswagen Golf Diesel 2009 Mode D'emploi page 282

Evaporative Emission System
Venting of fuel vapors from the charcoal canister
while the engine is running involves using two
different paths. When boost pressure from the
turbocharger is present, fuel vapors cannot directly
fl ow into the intake manifold. In this case, the vapors
are directed to the intake side of the turbocharger.
Charcoal
Canister
Infl ow into Intake
Manifold (No
Charge Pressure)
Infl ow into Intake
Manifold (Charge
Pressure Present)
Intake
Manifold
Charge Air
Cooler
Air Intake System
When boost pressure is not present, the vapors are
drawn in through the intake manifold downstream
of the throttle body. A double check valve in the
evaporative system accomplishes this task.
Fuel Tank
Exhaust Gas
Turbocharger
Evaporative (EVAP)
Emission Canister Purge
Regulator Valve N80
Double Check Valve
33