300Tdi Discovery
17
EMISSION CONTROL
2
DESCRIPTION AND OPERATION
REV: 09/95
Exhaust emission control.
The fuel injection system provides accurately metered
quantities of fuel to the combustion chambers to
ensure the most efficient air to fuel ratio under all
conditions of operation. A further improvement to
combustion is made by measuring the oxygen content
of the exhaust gases to enable the quantity of fuel
injected to be varied, according to conditions, to
correct any unsatisfactory composition of the exhaust.
The main components of the exhaust emission
system are two Catalytic converters which are an
integral part of the front exhaust pipe assembly. The
Catalytic converters are included in the system to
reduce the emission, to atmosphere, of carbon
monoxide, oxides of nitrogen, and hydrocarbons. The
active constituents of the converters are platinum and
rhodium. The correct functioning of the converters is
dependent upon close control of the oxygen
concentration in the exhaust gas entering the catalyst.
The oxygen content of the exhaust gas is monitored
by the heated oxygen sensors. Information on the
heated oxygen sensors is contained in the relevant
Fuel System section,
See FUEL SYSTEM MFI,
Description and operation, or See FUEL SYSTEM
SFI, Description and operation, The ECM can then
make an appropriate adjustment to the fuel supply to
correct the composition of the exhaust.
CAUTION: Unleaded fuel only must be
used on vehicles fitted with catalytic
converters. As a reminder,a label to
indicate this is adhered to the inside of the fuel
filler flap. Furthermore the filler neck is designed
to accommodate only unleaded fuel pump
nozzles.