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Volvo 1990 780 Model
pg. 99 Servicing (cont.)
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 platinum-palladium. These
metals act as catalysts, permitting a chemical action 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 at the 600-1,200 mile (1,000-2,000 km)
service.
Lambda-sond (oxygen sensor) system
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 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
file:///K|/ownersdocs/1990/1990_780/90780_21.htm (4 of 7)12/30/2006 8:28:05 AM
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