Volvo 1997 850 - Manual (Page 230)

1997 Volvo 850
pg. 8:8 Servicing (cont.)
A - inlet manifold, B - EVAP valve,
C - charcoal canister, D - roll over
valve, E - line to fuel tank
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
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-way catalytic converter.
Secondary Air Injection (certain models)
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