Volvo 940 Owner's Manual page 183

1993 Volvo 940
B230 FD only:
Replace timing belt every 100,000 miles (160,000 km)
pg. 8:8 Servicing (cont.)
1 Battery
2 Injection control module
3 Ignition control module
4 Fuel filter
5 Fuel pump
6 Fuel feed pump
7 Mass air flow sensor *
8 Throttle position switch
9 Temperature sensor
10 Injector
11 Heated oxygen sensor
12 Charge air cooler (Turbo models)
* Pressure meter on certain models
Fuel system
The fuel injection system is all-electronic and microprocessor-controlled. It can continually compensate
for variations in engine load, speed and temperature to give the best economy and power. A mass air
flow sensor or a pressure meter on certain models, 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 control 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 nitrous gases) by a three-way catalytic converter.
Pulsed Secondary Air Injection
(certain models)
This system adds air to the hot exhaust gases as they are expelled from the engine. This causes a
secondary combustion of residual hydrocarbons and carbon monoxide, resulting in lower emissions
levels in the exhaust gases.
file:///K|/ownersdocs/1993/1993_940/93940_8_7.html (2 of 8)12/30/2006 9:44:37 AM