1995 LAND ROVER DISCOVERY engine

EMISSION CONTROL
1
FAULT DIAGNOSIS REV: 09/95 TESTING EVAPORATIVE EMISSION CONTROL -
PRE ADVANCED EVAPS
The following pressure test procedure is intended to
provide a method for ensuring that the system does
not leak excessively and will effectively control
evaporative emissions.
Equipment required.
Nitrogen cylinder (compressed air may be used to
pressure the system when there has NEVER been
fuel present in the fuel or evaporative control
systems).
Water manometer (0 - 30" H2O or more).
Pipework and a "T" piece.
Method.
1.Ensure that there is at least two gallons of fuel in
the petrol tank unless there has never been any
fuel in the system.
2.Disconnect, at the adsorption canister, the pipe
to the vapour separator.
3.Connect this pipe to the nitrogen cylinder and
the water manometer using the "T" piece.
4.Pressurize the system to between 26.5 and 27.5
inches of water, allow the reading to stabilize,
then turn off the nitrogen supply.
5.Measure the pressure drop within a period of 2
minutes 30 seconds. If the drop is greater than
2.5 inches of water the system has failed the
test. Note that a fully sealed system will show a
slight increase in pressure.
6.Should the system fail the test, maintain the
pressure in the system and apply a soap
solution round all the joints and connections until
bubbles appear to reveal the source of the leak.
7.Repeat the test and if successful, dismantle the
test equipment and reconnect the pipe to the
adsorption canister.LEAK DETECTION PROCEDURE - ADVANCED
EVAPS
1.Connect TestBook to the vehicle and confirm
that the fault code(s) displayed relate to an
EVAP system fault.
2.Examine components in fuel and EVAP system
for damage or poorly connected joints.
3.Repair or replace components to rectify any
faults found, then reset the Check Engine light
using TestBook.
4.Carry out Drive Cycle,
See Drive Cycle -
Advanced EVAPS
5.Using TestBook confirm that the Evaporative
Loss Control (ELC) Inspection and Maintenance
(IM) flag has cleared. This procedure should
confirm that the ELC test was carried out during
the drive cycle and that the fault was cured.
6.If the IM flag is still shown, use TestBook to
interrogate the engine management system to
ascertain which of the following situations exists:
·If a fault code is shown then further investigation
is required, proceed to the next step.
·If the IM flag is still shown, but no faults are
indicated the conditions for the ELC check have
not been met and the drive cycle must be
repeated.
7.Connect the Leak Detection/EVAP Diagnostic
Station to the vehicle and carry out the
procedures given in the operating instructions
supplied with the equipment.
8.Rectify faults indicated by the Leak
Detection/EVAP Diagnostic Station and return to
step 4.

17EMISSION CONTROL
2
FAULT DIAGNOSISADD: 09/95 DRIVE CYCLE - ADVANCED EVAPS
1.Switch on ignition for 30 seconds.
2.Ensure that coolant temperature is less than 140
°F (30°C).
3.Start engine and allow to idle for 2 minutes.
4.Perform 2 light accelerations (0 to 35 mph with
light pedal pressure).
5.Perform 2 medium accelerations (0 to 45 mph
with moderate pedal pressure).
6.Perform 2 hard accelerations (0 to 55 mph with
heavy pedal pressure).
7.Cruise at 60 mph for 5 minutes.
8.Cruise at 50 mph for 5 minutes.
9.Cruise at 35 mph for 5 minutes.
10.Allow engine to idle for 2 minutes.
11.Connect TestBook and check for fault codes.

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.

EMISSION CONTROL
5
REPAIR Rear sensors
9.Release sensor cable from clips.
10.Release multiplug from bracket and disconnect.
11.Unscrew and remove sensor from exhaust pipe
using special tool LRT-12-047 (LST134).Refit
12.Ensure mating faces are clean.
NOTE: New HO2S is supplied pre-treated
with anti-seize compound.
13.If refitting existing HO2S, coat threads with
anti-seize compound.
CAUTION: Do not allow anti-seize
compound to come into contact with HO2S
nose or enter exhaust system.
14.Position HO2S with new sealing washer on
exhaust pipe. Tighten to
20 Nmusing special
tool LRT-12-047 (not RH front sensor).
15.Reconnect multiplug to engine harness and
secure to bracket.
16. RH front sensor only:
Place coil bracket in position and fit nuts. Tighten
to
8 Nm.
CAUTION: Ensure sensor leads are
secured using clips provided. Failure to
correctly secure leads could result in
damage to HO2S.
17.Remove stands. Lower vehicle.

17EMISSION CONTROL
6
REPAIR CATALYTIC CONVERTER/FRONT PIPE - 4.0 V8
Service repair no - 17.50.09
WARNING: The removal of the exhaust
system must only be carried out when the
engine is cold.
Remove
1.Disconnect battery negative lead.
2.Raise vehicle on ramp.
3.Remove oxygen sensors
See Heated Oxygen
Sensor (HO2S) - 4.0 V8
4.Remove 4 nuts/bolts securing front anti-roll bar
brackets.
5.Remove 6 nuts securing front pipe flanges to
manifolds.
6.Remove 2 nuts securing front pipe to
intermediate pipe.
7.With assistance, release front pipe from manifold
flanges.8.With assistance, release front pipe from
intermediate pipe.
9.With assistance, lower anti-roll bar.
10.With assistance, remove exhaust front pipe.
11.Remove flange gaskets and discard.
Refit
12.Reverse removal procedure.

Tdi
1
DESCRIPTION AND OPERATION DESCRIPTION
Air intake
The air cleaner is positioned to the right of the engine
and connected by hoses to a cold air intake duct and
the turbocharger inlet. A crankcase breather hose is
fitted between the air cleaner and the separator.
A single stage turbocharger, fitted between the
exhaust manifold and exhaust pipe, is connected by
hoses to the air cleaner and to an intercooler mounted
on the right of the radiator. The intercooler is
connected by a hose to the inlet manifold.
Fuel system
A 89 litre fuel tank is mounted at the rear of the
vehicle beneath the load space floor. The tank is
vented by a 2 way valve in the filler cap.
A mechanical lift pump, driven by the camshaft, is
mounted on the side of the engine.
A fuel filter, fitted with a replaceable element and
incorporating a water separator, is positioned on the
LH side of the bulkhead.
A Bosch Type injection pump, incorporating a cold
start advance unit and a high idle setting is mounted
on the LH side of the engine and is directly driven by
gears from the crankshaft. The pump meters and
distributes fuel to 4 pintle type injectors located in
pre-combustion chambers in the cylinder heads.
A return line passes excess fuel from the injection
pump and injectors back to the fuel tank.
Glow plugs
Four glow plugs are located in the cylinder head,
directly below each injector.Exhaust gas recirculation (EGR)
Exhaust gas recirculation is controlled by the EGR
control unit mounted in the passenger compartment
on the RH 'A' post behind the fascia and receives the
following inputs:
a. Engine temperature from coolant temperature
transmitter in No. 4 cylinder head.
b. Throttle position from the sensor on the injection
pump.
c. Engine speed from the tachometer.
d. EGR valve lift position.
When all correct signals are received, the EGR
solenoid allows vacuum to open the EGR valve and
recirculate a portion of the exhaust gas.

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.

Tdi
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DESCRIPTION AND OPERATION Exhaust Gas Recirculation (EGR)
Operation of the EGR system is dependent on the
following:
a. Engine temperature - must be between 20°C
and 100°C approx.
b. Engine speed - must be between 630 and 2850
rev/min.
c. Engine load - calculated by throttle position
sensor.
d. EGR valve lift position.
e. Duration of engine idling.
Under varying engine speed and load conditions the
control unit sends a signal to open the vacuum
modulator which allows a vacuum to be applied above
the EGR valve diaphragm, the vacuum supply being
taken from a 'T' connector in the brake servo hose.
This process is controlled by an engine speed/load
map stored in the EGR control unit memory.
Engine speed is measured by monitoring the
waveform present on one phase of the generator.
Throttle position is measured via a sensor mounted on
the fuel injection pump throttle lever. Closed loop
control is achieved by allowing the control unit to
continually monitor EGR valve lift via a position sensor
mounted on the valve; this valve lift is compared with
the actual valve lift required on the control unit map
and adjusted if necessary.
With coolant temperature between 20°C and 100°C;
the engine having just returned to idle, EGR will shut
off after 25-30 seconds idling.