1995 LAND ROVER DISCOVERY Workshop Manual

Mpi
3
SERVICE TOOLS
LRT-12-070 Sleeve crankshaft front oil seal
18G 1510
LRT-12-072 Replacer drift camshaft front oil seals
LRT-12-073 Remover crankshaft front oil seal
LRT-12-074 Remover adapter bit

12ENGINE
4
SERVICE TOOLS
LRT-12-076 Replacer needle crankshaft bearing

EMISSION CONTROL
1
DESCRIPTION AND OPERATION REV: 09/95 EMISSION CONTROL
Three systems are used to control the vehicle
atmospheric emissions these are:
Engine crankcase fume emissions.
Fuel tank Evaporative emissions
Engine exhaust gas emissions.
Crankcase ventilation system - 3.9 MFi models
only
The crankcase ventilation system which is an integral
part of the air supply to the engine combustion
chambers, is often overlooked when diagnosing
problems associated with engine performance. A
blocked ventilation pipe or filter or excessive air leak
into the inlet system through a damaged pipe or
leaking gasket can effect the mixture, performance
and economy of the engine.
1. Three way connector
2. Air filter
3. Oil separatorThe purpose of the crankcase ventilation system is to
ensure that any noxious gas generated in the engine
crankcase is rendered harmless by burning in the
combustion chambers as follows:
Oil laden noxious gas in the engine crankcase is
drawn through an oil separator 3 located on the right
cylinder head rocker cover, where the oil is separated
and returned to the sump. The gas flows through a
restrictor in the three way connection 1 and into the
inlet plenum chamber where it is drawn into the
combustion chambers and burned. The volume of
fresh air which is drawn from the atmospheric side of
the throttle butterfly to mix with the gas, depends on
the position of the throttle and the engine speed.
The air filter 2 fitted to the left cylinder head rocker
cover, must be maintained in clean condition to
ensure sufficient air enters the crankcase under
varying throttle openings and manifold depression, to
prevent excessive crankcase pressure or depression
developing.

17EMISSION 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.

EMISSION CONTROL
3
DESCRIPTION AND OPERATION REV: 09/95
EXHAUST SYSTEM
1. Manifold to front pipe connection.
2. Heated oxygen sensor - pre-catalytic converter.
3. Front silencer support bracket.
4. Heated oxygen sensor - post-catalytic converter.
5. Front pipe to silencer joint.
6. Silencer rear support bracket.
7. Rear silencer support bracket.

17EMISSION CONTROL
4
DESCRIPTION AND OPERATION REV: 09/95 Evaporative emission control system - pre
advanced EVAPS.
The system is designed to prevent harmful fuel vapour
from escaping to the atmosphere. The system
consists of a vapour separator tank, connected to the
fuel tank and located between the body inner and
outer panels on the right hand side of the vehicle near
the rear wheel arch. An adsorbtion canister,
containing activated charcoal, is positioned in the
engine compartment attached to the front right
valance. The two components are connected by a
pipe running the length of the chassis.
A Pressure relief to atmosphere.
B From fuel tank to separator.
C To adsorbtion canister.
D Pressure relief valve.
E Pressure relief valve.
F Shut-off valve.
G "Speed Fit" connectors.A pressure relief valve is fitted in the hose which is
open to atmosphere. This valve acts as a safety valve
should a build-up of pressure occur in the system, for
example if a hose became blocked or kinked. The
volume of vapour emitted, in such an instance, would
be acceptable.
A pressure relief valve is also fitted in the hose
connected to the adsorbtion canister and releases
vapor to the canister when the pressure in the
separator reaches between 5 and 7 Kpa.
In the top of the separator a shut-off valve is
incorporated in the vapor exit port to prevent the
possible presence of any liquid fuel being transmitted
to the adsorbtion canister should the vehicle roll over.
The adsorbtion canister, which is connected by a hose
to the plenum chamber, absorbs and stores the fuel
vapour from the fuel tank while the engine is not
running. When the engine is started, the vapour is
purged from the canister by air drawn through an
orifice in the base of the canister and by the influence
of vacuum at the top. The vapour drawn into the
plenum chamber through a solenoid operated purge
valve is finally burnt in the combustion chambers.
The purge valve, which is attached to the adsorbtion
canister support bracket, is controlled by the Engine
Control Module ECM which determines the most
emission acceptable time at which purging should
take place. This will normally be at engine speeds
above idle and when the vehicle is in motion. A signal
from the ECM to the purge valve operates the
solenoid and opens the valve to purge the canister of
fuel vapour.

EMISSION CONTROL
5
DESCRIPTION AND OPERATION REV: 09/95 EVAPORATIVE CONTROL SYSTEM - PRE
ADVANCED EVAPS
1. Adsorption canister and purge valve.
2. Location of vapour separator and pipes.
3. Fuel tank.

17EMISSION CONTROL
6
DESCRIPTION AND OPERATION ADD: 09/95 EVAPORATIVE EMISSION CONTROL SYSTEM -
ADVANCED EVAPS
Component location
1.EVAP canister
2.EVAP canister vent solenoid (ECVS)
3.EVAP canister purge valve
4.Anti-trickle fill valve
5.Liquid/vapour separator
6.Fuel filler neck assembly
7.Fuel tank
8.Fuel pump and gauge sender unit