Range Rover P38
EMISSION CONTROL
5
DESCRIPTION AND OPERATION
EMISSION CONTROL - LAND ROVER V8
Engine design has evolved in order to minimise the
emission of harmful by-products. Emission control
systems are fitted to Land Rover vehicles which are
designed to maintain the emission levels within the
legal limits pertaining for the specified market.
Despite the utilisation of specialised emission control
equipment, it is still necessary to ensure that the
engine is correctly maintained and is in good
mechanical order so that it operates at its optimal
condition. In particular, ignition timing has an effect on
the production of HC and NO
x
emissions, with the
harmful emissions rising as the ignition timing is
advanced.
CAUTION: In many countries it is against
the law for a vehicle owner or an
unauthorised dealer to modify or tamper
with emission control equipment. In some cases,
the vehicle owner and/or the dealer may even be
liable for prosecution.
The engine management ECM is fundamental for
controlling the emission control systems. In addition to
controlling normal operation, the system complies with
On Board Diagnostic (OBD) system strategies. The
system monitors and reports on faults detected with
ignition, fuelling and exhaust systems which cause an
excessive increase in tailpipe emissions. This includes
component failures, engine misfires, catalyst damage,
catalyst efficiency, fuel evaporative loss and exhaust
leaks.
When an emission relevant fault is determined, the
fault condition is stored in the ECM memory. For NAS
vehicles, the MIL warning lamp on the instrument
pack will be illuminated when the fault is confirmed.
Confirmation of a fault condition occurs if the fault is
found to be present during the driving cycle
subsequent to the one when the fault was first
detected.
See FUEL SYSTEM, Description and
operation.
The following types of supplementary control system
are used to reduce harmful emissions released into
the atmosphere from the vehicle:
•
Crankcase emission control - also known as
blow-by gas emissions from the engine
crankcase.
•
Exhaust emission control - to limit the
undesirable by-products of combustion.
•
Fuel vapour evaporative loss control - to
restrict the emission of fuel through evaporation
from the fuel system.
•
Fuel leak detection system (NAS only) - an on
board diagnostic (OBD) test to check the
evaporative emission system for the presence of
fuel evaporation leaks from the fuel tank to the
purge valve.
•
Secondary air injection system (NAS only) -
to reduce emissions experienced during cold
starting of the engine.
