Volvo 2003 C70 Operation And Care Manual page 67

fast highway driving may necessitate replacement sooner.
Under normal driving conditions, spark plugs require no maintenance between replacement intervals. When installing
new plugs, be sure to use the right type and to tighten them correctly. When changing the plugs, clean the terminals
and rubber seals. Also check that the suppressor connectors are in good condition. Cracked or damaged connectors
should be replaced.
pg. 114 Fuel/emissions systems
Fuel system
The fuel system is all-electronic and is microprocessor-controlled. It can continually compensate for variation in
engine load, speed and temperature to give the best economy and power. A mass air flow sensor measures the inducted
air. In this way the system can make instantaneous adjustments for changes in air temperature or density, thus always
assuring the best economy with the lowest possible exhaust emissions.
Heated oxygen sensor(s)
This is an emission control system designed to reduce emissions and improve 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 ratio to provide optimum conditions for combustion and efficient reduction of the
three major pollutants (hydrocarbons, carbon monoxide and oxides of nitrogen (NOx)) by a three-ways catalytic
converter.
Crankcase ventilation
Crankcase ventilation
The engine is provided with positive crankcase ventilation which prevents crankcase gases from being released into the
atmosphere. Instead, the crankcase gases are admitted to the intake manifold and cylinders.
Evaporative control system
The car is equipped with an evaporative control system which prevents gasoline vapor from being released into the
atmosphere.
The system consists of a fuel tank with filler pipe and cap, a rollover valve, a Fill Limit Vent Valve (FLVV), vapor
vent lines, a charcoal canister, a purge line, a purge control valve and engine connections.
In addition, there is a pressure sensor connected to the fuel tank and a filter-protected Canister Close Valve (CCV) on
the atmospheric side of the canister, for system diagnosis.
The gasoline vapor is channeled through the rollover valve and the FLVV via the vapor vent lines into the charcoal
canister, where it is stored. When the engine is started, the gasoline vapor is drawn from the charcoal canister to the