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Crankcase ventilation system
7 This system is fitted to all models, and
prevents the gases produced in the crankcase
from being released into the atmosphere, at
the same time preventing a build-up of
pressure in the crankcase (see illustration).
8 Crankcase gases are drawn into the air inlet
tract, where they are mixed with clean air. The
gases are then burnt with the fuel/air mixture
in the engine, and expelled through the
exhaust.
Electro-pneumatic ignition timing
retarding system
9 This system is used on models fitted with
the Mono-Jetronic A2.2 fuel injection system,
and reduces the nitrous oxide (NOx) content
in the exhaust gases (see illustration). This is
achieved by reducing the temperature at the
end of the combustion by reducing the
ignition advance at certain engine
temperatures.
10 The engine temperature is measured by a
coolant temperature sensor, and this
information is transmitted to the electronic
control unit, which controls the solenoid valve.
Under certain engine temperature conditions,
the solenoid valve cuts off the vacuum to the
distributor vacuum capsule, therefore
reducing the ignition advance.
Catalytic converter
11 Catalytic converters have been
introduced progressively on all models in the
range, to meet emissions regulations.
12 The catalytic converter is located in the
exhaust system, and operates in conjunction
with an exhaust gas oxygen sensor to reduce
exhaust gas emissions. The catalytic
converter effectively cleans the exhaust gases
by speeding up their decomposition.
13 In order for a catalytic converter to
operate effectively, the air/fuel mixture must
be very accurately controlled, and this is
achieved by measuring the oxygen content of
the exhaust gas. The oxygen sensor transmits
information on the exhaust gas oxygen
content to the electronic control unit, which
adjusts the air/fuel mixture strength
accordingly.
4D•2 Exhaust and emission control systems
1.7 Typical crankcase ventilation system
1 Oil filler cap with oil trap
2 Air filter
3 Throttle valve
4 Inlet manifold
5 Jet
6 Ventilation hose
7 Calibrated jet
8 Sump
9 Camshaft cover