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2
Activated charcoal filter system
Function
Depending upon the air pressure and ambient temperature, fuel
vapour will form above the level of fuel in the tank.
The activated charcoal filter system prevents these HC emissions
escaping to the atmosphere.
Fuel vapours pass from the highest point in the tank (on filler neck)
through the expansion tank and into the activated charcoal filter.
The activated charcoal stores these vapours like a sponge.
When the car is being driven and the Lambda control is active
(engine warm), the activated charcoal filter system solenoid valve
1 - N80- is activated (pulsed) by the engine control unit depending
on load and engine speed. The opening period depends on the
input signals.
During the purging procedure (regeneration of activated char‐
coal), the intake manifold vacuum draws fresh air through the vent
of the activated charcoal filter. The fuel vapours stored in the ac‐
tivated charcoal and fresh air are fed to combustion in metered
quantities.
The activated charcoal filter solenoid valve 1 - N80- is closed
when it is not supplied with current (e.g. open circuit). The acti‐
vated charcoal filter will not be purged.
Note
♦
Hose connections are secured with either spring-type or
clamp-type clips.
♦
Always renew crimp-type clips with spring-type clips.
♦
Spring-type clip pliers - VAS 5024A- or hose clip pliers -
V.A.G 1921- are recommended for installation of spring-type
clips.
Assembly overview - parts of activated charcoal filter system
⇒ page 148
Observe safety precautions
⇒ page 128
.
Observe rules for cleanliness
⇒ page 128
.
2.1
Assembly overview - parts of activated charcoal filter system
Phaeton 2003 ➤
6-cylinder injection engine - Edition 02.2014
148
Rep. gr.20 - Fuel supply system