air filter LAND ROVER DISCOVERY 1995 Owner's Manual

19FUEL SYSTEM
4
DESCRIPTION AND OPERATION OPERATION
Diesel engines operate by compression ignition. The
rapid compression of air in the cylinder during the
compression cycle heats the injected fuel, causing it
to self ignite. During cold starting, automatically
controlled glow plugs assist in raising the temperature
of the compressed air to ignition point.
A cold start advance unit advances the injection timing
to further assist starting. Idle quality is improved by
the high idle setting.
The engine is supplied with pre-compressed air by a
single stage turbocharger.
Exhaust gases passing over a turbine cause it to
rotate, driving a compressor mounted on the turbine
shaft. Air drawn from the cold air intake passes, via
the air cleaner, to the turbocharger where it is
compressed. The compressed air passes to the
cylinders via an intercooler, which reduces the
temperature of the compressed air, increasing its
density.
Fuel is drawn from the tank by a mechanical lift pump
and passes to the injection pump via a filter. In
addition to removing particle contamination from the
fuel, the filter incorporates a water separator, which
removes and stores both bound and unbound water.
The injection pump meters a precisely timed, exact
quantity of fuel to the injectors in response to throttle
variations, injection timing varying with engine speed.
Any excess fuel delivered to the injection pump is not
injected, passing back to the tank via the fuel return
line.
Fuel is injected in a finely atomised form into a
pre-combustion chamber in the cylinder head where it
ignites. The burning fuel expands rapidly into the main
combustion chamber, creating extreme turbulence
which mixes the burning fuel thoroughly with the
compressed air, providing complete combustion.
Cold Starting is assisted by glow plugs, a cold start
advance unit and a high idle setting.Glow plugs
Glow plug operation is controlled by a timer unit, start
relay and resistor. When the ignition is turned on the
timer unit is energised, the glow plugs start to operate
and a warning light on the dashboard illuminates,
remaining illuminated until the glow plugs are
automatically switched off.
The length of time the glow plugs will operate is
dependent on under bonnet temperature, which is
monitored by a sensor located in the timer unit.
Starting the engine results in the power supply to the
glow plugs passing through the resistor, which
reduces their operating temperature. The glow plugs
are cut out either by the temperature sensor in the
timer, or by a microswitch on the injection pump which
operates when the throttle is depressed.
Cold start advance
The cold start advance unit is connected to the engine
cooling system via hoses. It contains a temperature
sensitive element which is retracted when cold and
pulls the advance lever, via cable, towards the rear of
the pump against spring pressure. As coolant
temperature rises, the cold start element expands
releasing tension on the cable and allowing spring
pressure to move the advance lever forwards.

19FUEL SYSTEM
6
REPAIR FUEL FILTER ELEMENT
Service repair no - 19.25.07
Remove
1.Disconnect battery negative lead.
2.Clean area around filter head.
3.Place a suitable container beneath filter bowl to
collect any spillage.
4.Loosen bleed screw.
5.Loosen drain tap, allow fuel to drain into
container.
6.Unscrew filter element, discard element.
Refit
7.Clean seal and seating in filter head.
8.Lubricate filter element seal with fuel.
9.Position filter element to filter head and hand
tighten.
10.Reconnect battery negative lead.
11.Crank engine until fuel is drawn through the
system and starts.INTERCOOLER
Service repair no - 19.42.15
Remove
1.Disconnect battery negative lead.
2.Release 2 clips securing fan cowl to radiator top
cover.
3.Remove 4 bolts securing radiator top cover,
remove top cover.
4.Remove nut, bolt and washers securing
intercooler side cover bracket to bonnet [hood]
platform.
5.Release bracket from side cover lug, position
bracket and power steering reservoir aside.
6.Position side cover away from intercooler.
7.Loosen 2 clips and disconnect top hose from
intercooler.
8.Loosen 2 clips and disconnect bottom hose from
intercooler.

MFI
3
FAULT DIAGNOSIS FUEL PRESSURE CHECK
In order to check the fuel pressure it is necessary to
first depressurise the fuel system as follows:
WARNING: Under normal operating
conditions the multiport fuel injection
system is pressurised by a high pressure
fuel pump, operating at up to 2.3 to 2.5 bar. When
engine is stationary pressure is maintained within
system. To prevent pressurised fuel escaping and
to avoid personal injury it is necessary to
depressurise multiport fuel injection system
before any service operations are carried out.
If vehicle has not been run there will be a small
amount of residual pressure in fuel line. The
depressurising procedure must still be carried out
before disconnecting any component within the
fuel system.
The spilling of fuel is unavoidable during this
operation. Ensure that all necessary precautions
are taken to prevent fire and explosion.
A Pressure gauge 18G1500
B Fuel tank and pump
C Fuel filter
D Fuel injectors x 8
E Regulator1.Remove fuel pump relay module.
See Repair,
Multiport Fuel Injection Relay
2.Start and run engine.
3.When sufficient fuel has been used to cause fuel
line pressure to drop, injectors will become
inoperative, resulting in engine stall. Switch off
ignition.
4.Disconnect battery negative lead. .
NOTE: Fuel at low pressure will remain in
system. To remove low pressure fuel,
place absorbent cloth around fuel pipe at
the filter during disconnection.
5.Connect the pressure gauge on the outlet from
the filter, located on the chassis under the right
rear wheel arch.
6.Reconnect the battery and turn the ignition to
position II while observing the pressure gauge.
Results
Expected reading 2,39-2,672 kgf/cm
2
Pressure drop-max 0.7 kgf/cm2in one minute.
If pressure is low check that filter is not blocked
and pump is operating satisfactorily. Then
recheck pressure. If pressure is still low renew
regulator.
See Repair, Fuel Pressure
Regulator

19FUEL SYSTEM
6
REPAIR ENGINE COOLANT TEMPERATURE SENSOR
Service repair no - 19.22.18
Remove
1.Position drain tray to collect coolant spillage.
2.Disconnect multiplug from coolant sensor.
3.Remove sensor from thermostat housing.
4.Remove and discard copper washer.
Refit
5.Fit a new copper washer.
6.Fit sensor and tigten securely.
7.Top-up cooling system.
8.Run engine, check for water leaks around
sensor.DEPRESSURISING FUEL SYSTEM
WARNING: Under normal operating
conditions the Multiport fuel injection
system is pressurised by a high pressure
fuel pump, operating at up to 2.3 to 2.5 bar When
engine is stationary pressure is maintained within
system. To prevent pressurised fuel escaping and
to avoid personal injury it is necessary to
depressurise multiport fuel injection system
before any service operations are carried out.
If vehicle has not been run there will be a small
amount of residual pressure in fuel line. The
depressurising procedure must still be carried out
before disconnecting any component within the
fuel system.
The spilling of fuel is unavoidable during this
operation. Ensure that all necessary precautions
are taken to prevent fire and explosion.
1.Remove fuel pump relay module.
See
Multiport Fuel Injection Relays
2.Start and run engine.
3.When sufficient fuel has been used to cause fuel
line pressure to drop, injectors will become
inoperative, resulting in engine stall. Switch off
ignition.
4.Disconnect battery negative lead.
NOTE: Fuel at low pressure will remain in
system. To remove low pressure fuel,
place absorbent cloth around fuel feed
hose at fuel rail.
5.Disconnect either:
a) Nut and olive at fuel rail
OR
b) Hose at inlet end of fuel filter.
Refit
6.Refit fuel feed hose.
7.Refit fuel pump relay module, reconnect battery.
8.Crank engine (engine will fire in approximately 6
to 8 seconds).

MFI
17
REPAIR FUEL FILTER
Service repair no - 19.25.02
Remove
WARNING: Spilling of fuel is unavoidable
during this operation. Ensure all
necessary precautions are taken to
prevent fire and explosion.
WARNING: Ensure fuel handling
precautions given in Section 01 -
Introduction are strictly adhered to when
carrying out following instructions.
1.Depressurise fuel system.
See Depressurising
Fuel System
2.Access to filter is gained through right hand rear
wheel arch.
3.Clean area around hose connections to prevent
ingress of foreign matter into fuel system. Clamp
inlet and outlet hoses to prevent fuel spillage
when disconnecting hoses.
4.Loosen two fuel line unions and remove hoses.
Plug ends of hoses to prevent ingress of dirt.
5.Release securing bolt and bracket and remove
filter from chassis side member.
Refit
6.Fit a new filter observing direction of flow arrows
stamped on canister.
7.Tighten securing nut and bolt.
8.Fit inlet and outlet hoses. Tighten to
30Nm.
9.Refit fuel pump relay module, reconnect battery.
10.Start engine and inspect for fuel leaks around
hose connections.

19FUEL SYSTEM
18
REPAIR FUEL PIPES
Service repair no - 19.40.92
WARNING: Depressurise fuel system.See
Depressurise Fuel System
before
disconnecting any fuel pipes ensure that
all necessary precautions are taken against fuel
spillage
WARNING: Ensure fuel handling
precautions given in Section 01 -
introduction are strictly adhered to when
carrying out following instructions.
KEY
1. Fuel feed hose to fuel rail.
2. Fuel return hose to fuel tank.
3. Rigid fuel feed pipe.
4. Rigid fuel return pipe.
5. Fuel filter.6. Rigid fuel feed pipe to filter.
7. Breather hose.
8. In-tank fuel pump.
9. Fuel filler neck.
10. Fuel tank.

MFI
1
SPECIFICATIONS, TORQUE TORQUE VALUES
NOTE: Torque wrenches should be regularly checked for accuracy to ensure that all fixings are
tightened to the correct torque.
Nm
Air-Bypass valve (stepper motor) 20...............................................................
All flexible hose securing clamps 1,3...............................................................
Fuel feed pipe - hose to fuel rail 22.................................................................
Fuel filter 31....................................................................................................
EVAPORATIVE LOSS CONTROL SYSTEM
All flexible hose securing clamps 1,7...............................................................
METRIC Nm
M5 6...........................................................................
M6 9...........................................................................
M8 25...........................................................................
M10 45.........................................................................
M12 90.........................................................................
M14 105.........................................................................
M16 180.........................................................................
UNC / UNF
1/4 9...........................................................................
5/16 24.........................................................................
3/8 39...........................................................................
7/16 78.........................................................................
1/2 90...........................................................................
5/8 136...........................................................................
NOTE: Torque values above are for all screws and bolts used except for those specified.

SFI
1
DESCRIPTION AND OPERATION ENGINE MANAGEMENT SYSTEM
Description
The engine management system (EMS) maintains
optimum engine performance over the entire
operating range. The correct amount of fuel is
metered into each cylinder inlet tract and the ignition
timing is adjusted at each spark plug.
The system is controlled by the ENGINE CONTROL
MODULE (ECM) which receives data from sensors
located on and around the engine. From this
information it provides the correct fuel requirements
and ignition timing at all engine loads and speeds.
The fuel injection system uses a hot wire Mass Air
Flow Sensor to calculate the amount of air flowing into
the engine.
The ignition system does not use a distributor. It is a
direct ignition system (DIS), using four double ended
coils. The circuit to each coil is completed by
switching inside the ECM.
The on board diagnostic system detects any faults
which may occur within the EMS. Fault diagnosis
includes failure of all EMS sensors and actuators,
emissions related items, fuel supply and exhaust
systems.
The system incorporates certain default strategies to
enable the vehicle to be driven in case of sensor
failure. This may mean that a fault is not detected by
the driver. The fault is indicated by illumination of the
malfunction indicator light (MIL) on North American
specification vehicles.
A further feature of the system is 'robust
immobilisation'.Crankshaft position sensor (CKP Sensor)
The crankshaft position sensor is the most important
sensor on the engine. It is located in the left hand side
of the flywheel housing and uses a different thickness
of spacer for manual and automatic gearboxes. The
signal it produces informs the ECM:
- the engine is turning
- how fast the engine is turning
- which stage the engine is at in the cycle.
As there is no default strategy, failure of the
crankshaft sensor will result in the engine failing to
start. The fault is indicated by illumination of the
malfunction indicator light (MIL) on North American
specification vehicles.
Camshaft position sensor (CMP Sensor)
The camshaft position sensor is located in the engine
front cover. It produces one pulse every two
revolutions. The signal is used in two areas, injector
timing corrections for fully sequential fuelling and
active knock control.
If the camshaft sensor fails, default operation is to
continue normal ignition timing. The fuel injectors will
be actuated sequentially, timing the injection with
respect to top dead centre. Injection will either be
correct or one revolution out of synchronisation. The
fault is not easily detected by the driver. The fault is
indicated by illumination of the malfunction indicator
light (MIL) on North American specification vehicles.
Mass air flow sensor (MAF Sensor)
The 'hot wire' type mass air flow sensor is mounted
rigidly to the air filter and connected by flexible hose to
the plenum chamber inlet. The sensing element of the
MAF Sensor is a hot wire anenometer consisting of
two wires, a sensing wire which is heated and a
compensating wire which is not heated. Air flows
across the wires cooling the heated one, changing its
resistance. The ECM measures this change in
resistance and calculates the amount of air flowing
into the engine.
As there is no default strategy, failure will result in the
engine starting, and dying when it reaches 550
rev/min, when the ECM detects no MAF Sensor
signal. The fault is indicated by illumination of the
malfunction indicator light (MIL) on North American
specification vehicles.

SFI
11
DESCRIPTION AND OPERATION ADD: 09/95 Fuel Filler Neck Assembly
The filler neck consists of a stainless steel upper
section and a convolute nylon lower section. The
nylon lower is joined at one end to the tank and at the
other to the stainless upper section where both joints
utilise a short piece of rubber hose. The joint at the
fuel tank is secured using a spring assisted hose clip
which has a shear off cap.
NOTE: The spring assisted clip must never
be re-used, if removed a new clip of the
same type must be fitted.
Tank vent connections are achieved using serviceable
plastic quickfit connectors. The filler cap is tethered to
the body of the vehicle. Only a cap of this type must
be used as a replacement.Fuel Lines
The fuel lines consist of two coated steel lines fitted
along the length of the chassis from the fuel pump at
the rear of the vehicle to the connections at the fuel
rail on the engine, via a fuel filter on the feed line.
Connections at the pump are metal quickfits, while
those at the filter and fuel rail are threaded unions
utilising "O" rings for effective sealing.
NOTE: When the fuel filter is serviced or
the fuel rail joints are disconnected, new
"O" rings must always be fitted.
Connections at the fuel rail are made using "Saginaw"
screw thread type connectors with "O" rings as the
sealing medium. The fuel lines in the engine
compartment are made from a braided nylon material.
NOTE: This material must not be clamped
or kinked as this impairs its performance.

SFI
3
REPAIR FUEL SYSTEM - DEPRESSURISE
WARNING: Fuel pressure of up to 2.5 bar
will be present in the system, even if the
engine has not been run for some time.
Always depressurise the system before
disconnecting any components in the fuel feed
line (between fuel pump and pressure regulator).
The spilling of fuel is unavoidable during this
operation. Ensure that all necessary precautions
are taken to prevent fire and explosion.
NOTE: Fuel pressure can be relieved at
fuel rail feed union or fuel filter unions.
1.Position cloth around relevant union to protect
against fuel spray.
2.Carefully slacken union.
3.Tighten union to correct torque once pressure
has relieved.