1995 LAND ROVER DISCOVERY electrical

17EMISSION CONTROL
2
REPAIR HEATED OXYGEN SENSOR (HO2S)
Service repair no - 19.26.16
CAUTION: The removal of the sensors
from the exhaust system must only be
carried out when the engine is cold.
Remove
1.Disconnect battery negative lead.
2.Disconnect the electrical plugs from the sensors.
3.Unscrew and remove the sensors from the two
exhaust downpipes.
Refit
4.Coat the threads of the sensors with anti-seize
compound.
CAUTION: To ensure that the efficiency of
the sensor is not impaired, DO NOT allow
anti-seize compound to come into contact
with the sensor nose.
5.Screw in the sensor and tighten to the correct
torque using special tool LST134.
6.Connect the electrical plugs and battery lead.PURGE CONTROL VALVE
Service repair no - 17.15.39
Remove
1.Disconnect battery negative lead.
2.Disconnect multiplug from purge control valve.
3.Release clip and disconnect hose from valve.
4.Release valve from charcoal canister.
5.Remove valve.
6.Discard 'O' ring.
Refit
7.Clean valve and valve location.
8.Fit new 'O' ring to purge valve.
9.Position and secure valve to charcoal canister.
10.Connect hose to purge valve and secure with
clip.
11.Connect multiplug to valve.
12.Reconnect battery negative lead.

MFI
1
DESCRIPTION AND OPERATION DESCRIPTION
Hot Wire Multiport Fuel Injection
The 'Hot Wire' Multiport fuel injection system derives
its name from the mass air flow sensor which uses
one cold wire and one electrically heated wire to
measure the volume of air entering the engine.
The function of the system is to supply the exact
amount of fuel directly into the intake manifold
according to the prevailing engine operating
conditions.
To monitor these conditions, various sensors are fitted
to the engine to measure engine parameters. Data
from the sensors is received by the Engine control
module (ECM), the ECM will then determine the exact
amount of fuel required at any condition.
The ECM having received data from the sensors
produces pulses, the length of which will determine
the simultaneous open time of each bank of injectors
in turn, which will govern the amount of fuel injected.
Engine control module - ECM
The Multiport fuel injection system is controlled by the
14 CUX Engine Control Module comprising of a
microprocessor with integrated circuits and
components mounted on printed circuit boards. The
ECM is connected to the main harness by a 40 pin
plug.
Injectors
The eight fuel injectors are fitted between the
pressurized fuel rail and inlet manifold. Each injector
comprises a solenoid operated needle valve with a
movable plunger rigidly attached to the nozzle valve.
When the solenoid is energized the plunger is
attracted off its seat and allows pressurized fuel into
the intake manifold.Engine coolant temperature sensor
The engine coolant temperature sensor is located in
the front of the thermostat housing. The sensor
provides engine coolant information to the ECM. The
ECM increases the injector opening time when cold to
provide improved driveability, and reduces the
opening time as the engine reaches normal operating
temperature.
Engine fuel temperature sensor
The engine fuel temperature sensor is located in the
rail on the RH side of the ram housing. The sensor
sends fuel temperature data to the ECM, the ECM on
receiving the data will adjust the injector open time
accordingly to produce good hot starting in high
ambient temperatures.
Idle air control valve
The idle air control valve is screwed into a housing
attached to the rear of the plenum chamber, between
the plenum chamber and bulkhead. The idle air
control valve has two windings which enable the
motor to be energised in both directions thus opening
or closing the air valve as required by the ECM.
The idle air control valve will open and allow extra air
into the plenum chamber to maintain engine idle
speed when the engine is under increased (Electrical
and Mechanical) loads.
The idle air control valve will control engine idle speed
when the vehicle is stationary.
Heated oxygen sensors (0
2sensors) - Catalyst
vehicles
The two heated oxygen sensors are located forward
of the catalysts mounted in the exhaust downpipes.
The sensors monitor the oxygen content of the
exhaust gases and provide feedback information of
the air/fuel ratio to the ECM. Each sensor is heated by
an electrical element to improve its response time
when the ignition is switched on.

MFI
3
DESCRIPTION AND OPERATION Tune select resistor -
To suit individual market requirements a tune select
resistor is connected across pins 5 and 27 of the
ECM.
It is located adjacent to the ECM, and strapped to the
MFI cable assembly. The value of the resistor is
dependent on the market application:
Red wire, 180 ohms, Australia, Rest of world.
Green wire, 470 Ohms, UK and Europe - non catalyst.
Yellow wire 910 Ohms, Saudi non catalyst.
White wire, 3K9 Ohms, European catalyst
Condenser fans
It should be noted that under high coolant
temperatures, when the engine is switched off, the
condenser fans will be activated and will run for
approximately ten minutes.Vehicle speed sensor
The vehicle speed sensor is located on the side of the
Transfer box adjacent to the parking brake. The
sensor provides road speed data to the ECM. The
ECM in turn detects vehicle movement from the road
speed input and ensures that idle air control mode is
disengaged. Should the vehicle speed sensor fail in
service the ECM idle air control would become erratic.
The sensor also provides road speed data to the
electric speedometer and cruise control ECU.
Inertia fuel shutoff switch
The inertia fuel shutoff switch is a mechanically
operated switch, located on the bulkhead adjacent to
the washer reservoir under bonnet [hood].
The switch is normally closed and is in line with the
fuel pump. In the event of a sudden impact the switch
opens, and disconnects the electrical feed to the fuel
pump. The switch is reset by pressing down the
button.
WARNING: Check the integrity of the fuel
system before the inertia switch is reset.
Relay modules
The two multiport fuel injection relays are located in
the RH footwell area behind the 'A' post panel. The
main relay module is energized via the ECM when the
ignition is switched on and supplies current to the
multiport fuel injection system. The fuel pump relay
module is energized by the ECM which in turn
operates the fuel pump to pressurize the fuel system.

MFI
7
DESCRIPTION AND OPERATION MICRO PROCESSOR POWER CHECK
(Instrument binnacle - Service use only)
As part of the engine starting procedure, this symbol
will illuminate momentarily.
FUEL INJECTION SYSTEM
CAUTION: The fuel system incorporates
fine metering components that would be
affected by any dirt in the system;
therefore it is essential that working conditions
are scrupulously clean. If it is necessary to
disconnect any part of the fuel injection system,
the system MUST be depressurized. All openings
left open after the removal of any component from
the fuel system, MUST be sealed off to prevent
ingress of dirt.ENGINE SETTING PROCEDURE
If a major overhaul has been undertaken of the fuel
injection/engine system, the following check and
adjustments must be carried out before attempting to
start the engine.
1.Spark plug gaps.
See ENGINE TUNING DATA,
Information, Engine 3.9 V8i
2.Ignition timing.See ELECTRICAL,
Adjustment, Ignition Timing
CAUTION: Catalyst vehicle - if the engine
is misfiring, it should be immediately shut
down and the cause rectified. Failure to do
so will result in irreparable damage to the
catalysts.
NOTE: If the previous checks and
adjustments are satisfactory but the
engine will not start, the ignition and fuel
injection electrical circuits must be checked using
the appropriate recommended equipment.

MFI
1
FAULT DIAGNOSIS ENGINE TUNING
Circuit fault diagnosis may be carried out on all V8i
vehicles, using Testbook. Testbook will guide the
operator by visual prompts through a series of
diagnostic checks.
Before commencing any fault diagnosis, the following
preminary checks must be carried out.
Preliminary checks
CAUTION: Catalyst exhaust: If engine is
misfiring or fails to start within 12 seconds
the cause must be rectified. Failure to do
so will result in irreparable damage to the
catalysts. After rectification the engine must be
run at 1500 rev/min (no load) for 3 minutes to
purge any accumulation of fuel in the system.
1.Check that the inertia fuel shut off switch is not
tripped.
2.Check fuse in main fuse panel.
3.Check for ample fuel in tank.
4.Check air inlet system for possible leaks into the
intake manifold.
5.Check HT cables for correct firing order and
routing.
6.Check ignition timing.
Only when the above checks have been carried out,
should circuit diagnosis begin.
See Electrical
Trouble Shooting Manual.
INJECTOR TESTS
NOTE: Before removing any of the
injectors, remove and examine the spark
plugs, check for consistent colouration of
plugs. A leaking injector will result in the
appropriate spark plug being 'sooted up'.
The following test may only be carried out using
suitable injector test equipment.
Leak Test
Leak test with the injectors closed but pressurise to
2.54 Kgf/cm
2. No injector should leak more than 2
drops of fuel per minute.
Fuel Delivery Test
Fuel delivery test with the injector open and
pressurised as above, fuel delivery from each injector
should be 160-175cc per minute using white spirit, or
180-195cc per minute using petrol at 20°C±2°C.

19FUEL SYSTEM
2
FAULT DIAGNOSIS BASE IDLE SPEED SETTING
NOTE: Base idle speed is set at factory. It
should not require further adjustment
unless plenum chamber is changed. The
adjustment screw is sealed with a plug to prevent
unauthorised alteration. Check ignition timing
before attempting following procedure, since this
will affect idle speed.
Equipment required
Two blanking hoses.these are manufactured using
a new air by-pass valve hose - Part No.ETC7874. Cut
two equal pieces 90mm long from hose and seal one
end of each, using 13mm diameter bar. Use a suitable
clamp to ensure an air tight seal.
Checking procedure
1.Drive vehicle at least two miles until engine and
transmission are hot. Switch off engine.
2.Check all electrical loads are OFF, including air
conditioning.
3.Remove air by-pass valve hose.
4.Fit blanking hoses to both plenum chamber and
air by-pass valve. Ensure hoses are securely
fitted to prevent air leaks. Note throttle cable and
cruise control actuator have been omitted from
illustration.5.Start engine and check idle speed is within
limits.
See ENGINE TUNING DATA,
Information, Engine 3.9 v8i
Adjusting base idle speed
6.Drill tamper proof plug and insert a self tapping
screw to enable plug to be extracted.
7.Start engine, adjust idle screw clockwise to
decrease or counter-clockwise to increase idle
speed.
8.Stop engine, remove blanking hoses. Reconnect
hose to plenum.
9.Fit new tamper proof plug.

19FUEL SYSTEM
8
REPAIR 10.Remove fuel rail and injectors.
11.Remove injector retaining clips, ease injectors
from rail. Remove and discard 'O' rings from
injectors.
12.Remove fuel pressure regulator if required.
Refit
13.FitNEW'O' rings, to injectors. Lightly coat 'O'
rings with silicon grease 300. Insert injectors into
fuel rail, multi-plug connections facing outwards.
14.Refit retaining clips.
CAUTION: Care must be taken when
refitting the fuel rail and injectors to intake
manifold to prevent damage to 'O' rings.
15.Fit aNEW'O' ring to pressure regulator lightly
coat 'O' ring with silicon grease 300 and secure
regulator to the fuel rail.
16.Fit fuel rail and heater pipe assemblies to intake
manifold. Secure rail and pipes in position with
five bolts.
17.Reverse removal procedure. 2 to 7.
18.Pressurise fuel system and check for fuel leaks
around injectors and pressure regulator.PLENUM CHAMBER
Service repair no - 19.22.46
Includes throttle levers and throttle disc
Remove
1.Disconnect battery negative lead.
2.Disconnect electrical multi-plug from bypass air
valve.
3.Disconnect vacuum hose adjacent to bypass air
valve.
4.Mark an identification line on throttle cable outer
to assist re-assembly.
5.Remove clevis pin from throttle cable.
6.Pry adjustment thumb wheel from throttle
bracket. Lay cable aside.
7.Remove retaining clip and clevis pin from kick
down cable (automatic vehicles).
8.Apply adhesive tape behind rear adjustment nut
on kick down cable to prevent nut moving.
9.Remove front lock nut. Remove cable and lay
aside.
10.Remove cruise control vacuum hose.
11.Remove intake hose from neck of plenum
chamber.
12.Disconnect throttle position sensor multi-plug.
13.Remove PCV breather hose.
14.Disconnect two coolant hoses and plug each
hose to prevent excessive loss of coolant.
Identify each hose for re-assembly.

19FUEL SYSTEM
22
REPAIR FUEL TANK
Service repair no - 19.55.01
WARNING: Ensure that fuel handling
precautions given in Section 01 -
introduction are strictly adhered to when
carrying out following instructions.
CAUTION: Before disconnecting any part
of fuel system, it is imperative that all dust,
dirt and debris is removed from around
components to prevent ingress of foreign matter
into fuel system.
Remove
1.Depressurise fuel system. Disconnect battery
negative lead.
2.Syphon fuel tank into a suitable container that
can be sealed afterwards.
ENSURE TANK IS DRAINED COMPLETELY.
(refer to Warning concerning fuel vapour and
spillage at start of procedure).
3.Remove carpet loadspace floor and tailgate.
4.Fold back sound insulation to reveal access
panel.
5.Remove access panel.
6.Disconnect electrical multi-plug.
7.Disconnect two fuel line unions from fuel pump.
8.Working underneath vehicle mark location of
anti-roll [sway] bar straps.
9.Remove rear anti-roll [sway] bar straps, and
allow bar to swing down clear of tank.
10.Remove tank filler and vent hoses at fuel tank.
11.Remove nut and bolt securing right hand side
fuel tank strap.
12.Disconnect evaporative control pipe at green
end of 'speedfit' connector.
NOTE: To disconnect 'speedfit' connector,
insert forked end of LRT-19-002 into slots
of connector see illustration. Press down
on collet and simultaneously pull pipe from
connector.