Volvo 740 1989 Owner's Maintenance Manual page 116

Classic Cars & Cycles www.ClassicCycles.org
1989 Volvo 740
Lambda-sond (oxygen sensor) system
This is an emission control system designed to reduce emissions and improve fuel economy. An oxygen sensor monitors the composition of
the exhaust gases leaving the engine. The exhaust gas analysis is fed into an electronic unit which continually influences the injectors. 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 3-way catalytic converter.
pg. 105 Servicing
Catalytic converter
This is a supplementary device in the exhaust system, designed to clean exhaust gases.
This device is mainly a container with a ceramic material insert, designed to let the exhaust gases pass through channels in the insert. The
channel walls are covered by a thin layer of platina-palladium. These metals act as catalysts, permitting chemical reaction to occur without
actually taking part in it.
The emission (CO, HC, NOX) content will increase if the catalytic converter is damaged. Lambda-sond equipped vehicles use Catalytic
Converters containing platinum and rhodium.
Torque Catalytic Converter mounting bolts
The Catalytic Converter mounting bolts should be torqued after the first 600-1,200 miles (1.000-2,000 km).
Caution: Vehicles with Catalytic Converter must use unleaded fuel only. Otherwise the Catalytic Converter will become ineffective. See
"Fuel requirements".
Intercooler
The B230F-Turbo engine employs a turbo-compressor to force air into the engine inlet manifold and an intercooler to cool the compressed
inlet air. The resulting increase in air flow raises pressure in the intake manifold by approx. 8 psi (over atmospheric pressure) and engine
power output by approx. 46 horsepower over that developed by the normally- aspirated engine.
The intercooler (which resembles a radiator) is located between the turbo-compressor and inlet manifold.