1995 LAND ROVER DISCOVERY length

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.

17EMISSION CONTROL
8
DESCRIPTION AND OPERATION ADD: 09/95 System operation
The system is designed to prevent fuel vapour
escaping to atmosphere, and consists of four roll-over
valves fitted internally in the fuel tank, connected to
the liquid/vapour separator by a nylon line. The
separator is mounted to the side of the filler neck. An
EVAP canister is positioned in the engine
compartment mounted on the right front side valance.
The liquid/vapour separator and EVAP canister are
connected by a nylon line which runs the length of the
chassis.
Pressure/vacuum relief valves are incorporated into
the fuel filler cap and are designed to protect the fuel
tank from permanent deformation in the event of
system pressure or vacuum exceeding the system
operating parameters. There are no other relief or
one-way valves in the system.
A vent line flow restrictor known as an anti-trickle fill
valve is fitted to the filler pipe in the line between the
tank and EVAP canister. The function of this valve is
to prevent overfilling the tank by trickling fuel in,
thereby preserving the vapour space in the tank to
allow for fuel expansion during hot weather.
The valve achieves this by blocking the vent line
during the fuel filling process. The valve is operated
by the action of inserting the filler gun so that when
the fuel in the tank reaches the level of the filling
breather, flow cut off occurs due to fuel filling the filler
pipe.During normal vehicle operation and when the engine
is switched off, the venting system between the fuel
tank and EVAP canister is open to allow the free
passage of vapour.
The EVAP canister, which is connected by a nylon
hose to the plenum chamber, absorbs and stores the
fuel vapour from the fuel tank when the engine is not
running. With the engine running, vapour is purged
from the EVAP canister by allowing outside air to be
drawn through the EVAP canister vent solenoid and
link pipe by the influence of manifold vacuum to the
EVAP canister purge connection on the canister.
Filter pads are fitted above and below the charcoal
and in the EVAP canister vent solenoid to prevent the
ingress of foreign matter into the purge line.
The EVAP canister purge valve, which is fitted in the
line from the EVAP canister to the plenum, is
controlled by the 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.
The EVAP canister vent solenoid is mounted on the
side of the EVAP canister bracket and is connected to
the EVAP canister by a length of large bore hose. The
ECVS is controlled by the ECM and is normally open.
The function of the ECVS is to block the air intake
side of the EVAP canister. When the system receives
an ECM signal the valve closes; this allows the
system leak check to take place. The leak check only
occurs when pre-determined vehicle operating
conditions are met.

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
2
ADJUSTMENT LOW AND HIGH IDLE SPEED
Adjust
The high idle speed (cold start idle) is
automatically set by the setting of the low idle
speed and can not be adjusted individually.
1.Check and adjust throttle cable.
2.Start engine and run it until normal operating
temperature is reached.
3.Using a suitable tachometer, check the engine
idle speed.
See ENGINE TUNING DATA,
Information, 300 Tdi Engine
4.If adjustment is necessary, loosen the locknut on
the injector pump.
5.Turn the adjustment screw either clockwise to
increase the engine speed or anti-clockwise to
decrease the speed. Run the engine at an
increased speed for a few seconds then check
the idle speed again.
6.When the correct speed has been achieved,
hold the adjuster screw steady while tightening
the locknut.
NOTE: The low idle speed control is the
only permitted adjustment in service. Any
additional adjustments required must be
entrusted to authorised Bosch agents.CHECK TURBOCHARGER BOOST PRESSURE
For boost pressure.
See ENGINE TUNING DATA,
Information, 300 Tdi Engine
1.Disconnect, from turbocharger, hose to actuator.
Insert into a suitable "T" piece.
2.Connect a short length of suitable hose to
turbocharger and connect other end to "T" piece.
3.Connect a further length of hose to third leg of
the "T" piece and other end to a pressure gauge
capable of reading in excess of 61 cm Hg. The
pressure gauge hose must be capable of
reaching passenger compartment so that gauge
may be observed.
4.To check maximum boost pressure, drive
vehicle normally but in such a manner that full
throttle can be maintained whilst climbing a hill
with engine speed held steady between 2,500
and 3,000 rev/min.

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.

19FUEL SYSTEM
2
DESCRIPTION AND OPERATION Fuel pressure regulator
The fuel pressure regulator is mounted in the fuel rail
at the rear of the plenum chamber. The regulator is a
mechanical device controlled by plenum chamber
vacuum, it ensures that fuel rail pressure is
maintained at a constant pressure difference of 2.5
bar above that of the manifold.
When pressure exceeds the regulator setting excess
fuel is returned to the fuel tank.
Fuel pump
The electric fuel pump is located in the fuel tank, and
is a self priming 'wet' pump, the motor is immersed in
the fuel within the tank.
Air flow sensor
The hot-wire air flow sensor is mounted on a bracket
attached to the left hand valance, rigidly connected to
the air cleaner and by hose to the plenum chamber
inlet neck.
The air flow sensor consists of a cast alloy body
through which air flows. A proportion of this air flows
through a bypass in which two wire elements are
situated: one is a sensing wire and the other is a
compensating wire. Under the control of an electronic
module which is mounted on the air flow sensor body,
a small current is passed through the sensing wire to
produce a heating effect. The compensating wire is
also connected to the module but is not heated, but
reacts to the temperature of the air taken in, as engine
intake air passes over the wires a cooling effect takes
place.
The electronic module monitors the reaction of the
wires in proportion to the air stream and provides
output signals in proportion to the air mass flow rate
which are compatible with the requirements of the
ECM.Throttle position sensor
The throttle position sensor is mounted on the side of
the plenum chamber inlet neck and is directly coupled
to the throttle butterfly shaft.
The throttle position sensor is a resistive device
supplied with a voltage from the ECM. Movement of
the accelerator pedal causes the throttle valve to
open, thus rotating the wiper arm within the throttle
position sensor which in turn varies the resistance in
proportion to the valve position. The ECM lengthens
the injector open time when it detects a change in
output voltage (rising) from the throttle position
sensor.
In addition the ECM will weaken the mixture when it
detects the throttle position sensor output voltage is
decreasing under deceleration and will shorten the
length of time the injectors are open.
When the throttle is fully open, the ECM will detect the
corresponding throttle position sensor voltage and will
apply full load enrichment. This is a fixed percentage
and is independent of temperature. Full load
enrichment is also achieved by adjusting the length of
the injector open time.
When the throttle is closed, overrun fuel cut off or idle
speed control may be facilitated dependant on other
inputs to the ECM.
The throttle position sensor is 'self adaptive', which
means that adjustment is not possible. It also means
the throttle position sensor setting is not lost, for
example, when throttle stop wear occurs.
CAUTION: Do not attempt to adjust throttle
position sensor.

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.

STEERING
1
ADJUSTMENT POWER STEERING BOX
Service repair no - 57.10.13
WARNING: Adjustments of steering box
should not be required while in warranty
period. If box is stiff or tight and within
warranty, it must be returned to manufacturer. No
attempt must be made to introduce backlash.
1.Apply park brake, select 'P' in automatic
transmission and chock wheels. Support chassis
front on axle stands.
2.Remove engine undertray.
3.Disconnect drag link from steering drop arm.
4.Check torque to turn.
See Fault diagnosis,
Stiff Steering Checklist
5.Centralise steering box.See Centralise
Steering Box
NOTE: Only check for no backlash when
steering box is in central position.
NOTE: If steering wheel is not straight, it
should be repositioned.
See Repair,
Steering Wheel
The adjustment of the steering box ensures
any preload or end float present on centre is
removed.
6.The adjustment is obtained by rocking the drop
arm about centre whilst an assistant slowly
tightens the steering box adjuster screw.
7.Tighten the locknut when all backlash has been
removed.
8.Repeat the check for backlash. If backlash exists
loosen locknut and repeat adjustment
procedure.
9.Turn steering wheel lock to lock and check no
tightness exists.
10.Ensure front wheels are aligned and in straight
ahead position.
See Front Wheel Alignment
11.Adjust drag link 924 mm between ball joint
centres.
12.Connect drag link. Tighten to
40 Nm.
13.Lower vehicle to ground level and remove
chocks.
14.Road test vehicle.
See Fault diagnosis, Road
Test Procedure
NOTE: If steering wheel is not in straight
ahead position when vehicle is travelling
in a straight line, drag link length is
incorrect and is pushing drop arm away from
central position.
Drag link adjust
15.Right hand drive vehicles - if steering wheel is to
right, drag link is too long. If steering wheel is to
left drag link is too short.
Left hand drive vehicles - if steering wheel is to
right, drag link is too short. If steering wheel is to
left drag link is too long.
16.Adjust drag link until steering wheel points
straight ahead when vehicle is travelling in a
straight line.
CENTRALISE STEERING BOX
1.To centralise the box, insert a suitable peg (hole
size 8.06 mm) into the rear of the drop arm and
into the steering box casing to enable rapid and
accurate setting on centre.