2004 VOLVO XC70 Purge valve

2004 VOLVO XC70

pg. 132 Fuel/emissions systems
Fuel system
The fuel system continually compensates for variation in engine load, sp\
eed and temperature. A mass air
flow sensor continuously measures the inducted air and makes rapid adjus\
tments for changes in air
temperature and density, to balance fuel economy, emissions, and engine \
power requirements.
Heated oxygen sensor
This is an emission control system designed to reduce emissions and impr\
ove fuel economy. The heated
oxygen sensor monitors the composition of the exhaust gases leaving the \
engine. The exhaust gas
analysis is fed into an electronic module. This adjusts the air/fuel rat\
io to improve combustion and
reduce the three major pollutants (hydrocarbons, carbon monoxide, and o\
xides of nitrogen (NOx)) via a
three-way catalytic converter.
Crankcase ventilation
The engine is provided with positive crankcase ventilation which prevent\
s crankcase gases from being
released into the atmosphere. Instead, the crankcase gases are routed to\
the intake manifold and
cylinders.
PremAir®
On the surface of the radiator in the engine compartment, there is a spe\
cial coating called PremAir®.
PremAir® works as a catalytic converter, converting most of the ozone\
passing through the radiator into
oxygen, thereby reducing harmful ground-level ozone.
Evaporative control system
The car is equipped with an evaporative control system, which prevents g\
asoline vapor from being
released into the atmosphere.
The system consists of a fuel tank with filler pipe and cap, two rollove\
r valves, a Fill Limit Vent Valve
(FLVV), vapor vent lines, a charcoal canister, a purge line, and a pur\
ge control valve and engine
connections. In addition, there is a pressure sensor connected to the fu\
el tank and a filter-protected
Canister Close Valve (CCV) on the atmospheric side of the canister, fo\
r system diagnosis.
The gasoline vapor is channeled through the rollover valves and the FLVV\
via the vapor vent lines into
the charcoal canister, where it is stored. When the engine is started, t\
he gasoline vapor is drawn from the
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