VW CGRA, Руководство по ремонту

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6 Activated charcoal filter system (ve‐
hicles for USA and Canada)
⇒ “6.1 Assembly overview - activated charcoal filter system”, page
207 .
⇒ “6.2 Checking fuel system for leaks”, page 208 .
Function
Fuel vapour forms above the surface of the fuel in the tank; the
quantity depends upon the air pressure and ambient temperature.
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 vehicle is being operated and the Lambda control is
active (engine warm), the activated charcoal filter system sole‐
noid valve 1 - N80- is activated (pulsed) by the engine control unit
- J623- 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 system solenoid valve 1 - N80- is
closed when it is not supplied with current (e.g. open circuit). The
activated charcoal filter will not be purged.
Description of leakage diagnosis
The activated charcoal filter system (including fuel tank) is equip‐
ped with leakage diagnosis which can detect if there is a leak in
the system.
The diagnosis is based on a pressure method and indicates leaks
with a diameter greater than 0.5 mm.
During the diagnosis, the fuel system diagnostic pump - V144-
develops pressure in the activated charcoal filter system. Once
the pressure is attained, the pump switches off. If the pressure
drops below a certain value, the pump switches on again. Self-
diagnosis monitors the intervals at which the pump is switched on
or off and, if the intervals are too short, writes an entry to the event
memory.
Touareg 2010 ➤ , Touareg 2015 ➤
6-cylinder direct-injection engine (3.6 l engine, 4V) - Edition 12.2019
206
Rep. gr.20 - Fuel supply system