001-055 Alfa 156 GB - Alfa Romeo serviss

GETTING TO KNOW YOUR CAR
188
EMISSION REDUCING DEVICES
(petrol engines)
Trivalent catalytic converter
(catalytic silencer)
The exhaust system is fitted with a catalyzer
formed of alloys of noble metals. It
is housed in a stainless steel container which
is able to resist the high operating temperatures.
The catalyzer converts the unburnt hydrocarbons,
carbon monoxide and nitrogen oxides
present in the exhaust gas (even if in
small quantities thanks to the electronic injection
and ignition system) into harmless
compounds.
WARNING
Due to the high temperatures
reached during operation
of the catalytic converter, the
vehicle should not be parked over
inflammable materials (paper, fuel
oils, grass, dry leaves, etc.).
Lambda probe
A sensor (lambda probe) measures the
content of oxygen present in the exhaust
gas. The signal transmitted by the lambda
probe is use by the injection and ignition
electronic control unit to adjust the air-fuel
mixture.
Anti-evaporation system
As it is impossible, even when the engine
is switched off, to prevent the formation of
fuel vapours, a system has been devised
which imprisons the vapours in a special activated
carbon container.
During operation of the engine, these
vapours are sucked up and sent to combustion.
EMISSION REDUCING DEVICES
(JTD engines )
Oxidising catalytic converter
Converts the polluting substances present
in the exhaust gases (carbon monoxide, unburned
hydrocarbons and particulate) into
harmless substances, thus reducing the
fumes and smell that are typical of diesel
engines.
The catalytic converter consists of a stainless
steel case that houses a ceramic honeycomb
body coated with noble metal used
as a catalyst.
Exhaust gas recirculation system
(E.G.R.)
This system recycles, i.e. re-uses, a varying
percentage of the exhaust gases, depending
on engine operating conditions.
It is used, when necessary, to control nitric
oxides.