engine LAND ROVER DEFENDER 1999 Workshop Manual

ENGINE MANAGEMENT SYSTEM
27
DESCRIPTION AND OPERATION The turbocharger is exposed to extremely high operating temperatures (up to 1000°C, 1832°F) because of the
hot exhaust gases and the high speed revolution of the turbine (up to 15,000 rev/min). In order to resist wear of
the turbine bearings a flow of lubrication oil is supplied from the engine lubrication system to keep the bearings
cool. Oil is supplied from a tapping at the front of the full-flow filter adaptor housing via a metal pipe with banjo
connections. Oil is returned to the sump via a metal pipe which connects to the cylinder block at a port below the
turbocharger assembly.
A heatshield is attached to the LH side of the engine to protect adjacent components from the heat generated at
the turbocharger. The heatshield is attached to the engine by 2 bolts. An additional bolt attaches the heatshield to
the turbocharger casting.
The ECM controls the amount of boost pressure the engine receives by way of the turbocharger. When full boost
is reached a control signal is sent to the wastegate modulator, and a vacuum is applied to the wastegate valve.
The wastegate valve opens, bypassing some of the exhaust gases away from the turbine to be output to the
exhaust system.
The engine should be allowed to idle for 15 seconds following engine start up and before the engine is switched
off to protect the turbocharger by maintaining oil supply to the turbine bearings.
INTERCOOLER
The intercooler is an air-to-air heat exchanger which lowers the intake air temperature to obtain a higher air
density for better combustion efficiency. The intercooler receives compressed air from the turbocharger via a
metal pipe. It cools the intake air via the intercooler matrix and delivers it to the intake manifold by means of a
rubber hose which connects between the intercooler outlet and the intake manifold. The rubber hose is connected
to ports at each end by metal clips.
The intercooler is located at the front of the engine bay, forward of the radiator.
ProCarManuals.com

18ENGINE MANAGEMENT SYSTEM
28
DESCRIPTION AND OPERATION OPERATION
Engine Management
The ECM controls the operation of the engine using stored information within its memory. This guarantees
optimum performance from the engine in terms of torque delivery, fuel consumption and exhaust emissions in all
operating conditions, while still giving optimum driveability.
The ECM will receive information from its sensors under all operating conditions, especially during:
Cold starting.
Hot starting.
Idle.
Wide open throttle.
Acceleration.
Adaptive strategy.
Backup strategy for sensor failures.
The ECM receives information from various sensors to determine the current operating state of the engine. The
ECM then refers this information to stored values in its memory and makes any necessary changes to optimise
air/fuel mixture and fuel injection timing. The ECM controls the air/fuel mixture and fuel injection timing via the
Electronic Unit Injectors (EUI), by the length of time the EUI’s are to inject fuel into the cylinder. This is a rolling
process and is called adaptive strategy. By using this adaptive strategy the ECM is able to control the engine to
give optimum driveability under all operating conditions.
During cold start conditions the ECM uses ECT information to allow more fuel to be injected into the cylinders.
This, combined with the glow plug timing strategy supplied by the ECM, facilitates good cold starting.
During hot start conditions, the ECM uses ECT and FT information to implement the optimum fuelling strategy to
facilitate good hot starting.
During idle and wide open throttle conditions, the ECM uses mapped information within its memory to respond to
input information from the TP sensor to implement the optimum fuelling strategy to facilitate idle and wide open
throttle.
To achieve an adaptive strategy for acceleration, the ECM uses input information from the CKP sensor, the TP
sensor, the ECT sensor, the MAP/IAT sensor, and the FT sensor. This is compared to mapped information within
its memory to implement the optimum fuelling strategy to facilitate acceleration.
Fuel Delivery / Injection Control
The fuel delivery/injection control delivers a precise amount of finely atomised fuel to mix with the air in the
combustion chamber to create a controlled explosion. To precisely control fuel delivery and control fuel injection,
the following input conditions must be met:
CKP information.
Injection timing map information.
FT information.
ECT information.
The ECM monitors the conditions required for optimum combustion of fuel in the cylinder from the various sensors
around the engine and then compares it against stored information. From this calculation, the ECM can adjust the
quantity and timing of the fuel being delivered into the cylinder. The ECM uses CKP information as follows:
To calculate engine speed.
To determine engine crankshaft position.
Engine speed and crankshaft position allows the ECM to determine fuel injection timing.
The ECM also uses ECT and FT information to allow optimum fuel delivery and injection control for all engine
coolant and fuel temperatures.
ProCarManuals.com

ENGINE MANAGEMENT SYSTEM
1
REPAIR ENGINE CONTROL MODULE (ECM)
Service repair no - 18.30.03
Remove
1.Release fixings and remove battery cover.
2.Disconnect battery negative lead.
3.Remove RH seat cushion, release clip and
remove ECM access panel.
4.Remove 3 bolts, release ECM and disconnect 2
multiplugs. Remove ECM.
Refit
5.Position new ECM and connect multiplugs.
6.Fit ECM and tighten bolts.
7.Fit access panel and RH seat cushion.
8.Reconnect battery negative lead.
9.Fit battery cover and secure with fixings.SENSOR - ENGINE COOLANT TEMPERATURE
(ECT)
Service repair no - 18.30.10
Remove
1.Disconnect battery negative lead.
2.Remove spring clip and disconnect ECT sensor
multiplug.
3.Position cloth around ECT sensor to absorb
coolant spillage.
4.Remove ECT sensor.
5.Remove sealing washer and discard.
Refit
6.Clean sealing washer, sensor threads and
sensor location.
7.Coat sensor threads with Loctite 577 and fit new
sealing washer.
8.Fit ECT sensor and tighten to20 Nm (14 lbf.ft).
9.Fit spring clip to multiplug and connect multiplug
to ECT sensor.
10.Top up cooling system.
11.Run engine to normal operating temperature.
Check for leaks around ECT sensor.
12.Reconnect battery negative lead.
ProCarManuals.com

18ENGINE MANAGEMENT SYSTEM
2
REPAIR SENSOR - CRANKSHAFT SPEED AND POSITION
(CKP)
Service repair no - 18.30.12
Remove
1.Disconnect CKP sensor multiplug.
2.Remove bolt, remove CKP sensor from gearbox
housing and discard’O’ring.
3.If fitted, collect spacer.
Refit
4.Clean gearbox housing and CKP sensor.
5.If fitted, refit spacer.
6.Fit new’O’ring, position CKP sensor to gearbox
housing and tighten bolt to10 Nm (7 lbf.ft).
7.Connect sensor multiplug.
ProCarManuals.com

19FUEL SYSTEM
2
DESCRIPTION AND OPERATION DESCRIPTION
General
The fuel delivery system comprises a fuel tank, fuel pump, fuel pressure regulator, five injectors and a fuel filter.
The system is controlled by the ECM, which energises the fuel pump relay and controls the operation and timing
of each injector solenoid.
Unlike other Diesel engines, the Td5 has no injection pump. The diesel direct injection system receives fuel at
pressure from a two stage fuel pump located in the fuel tank. The system incorporates a fuel return to the fuel
pump, via a fuel cooler attached to the inlet manifold, and a fuel filter. A fuel pressure regulator is located in a
housing on the rear of the cylinder head. The regulator maintains the fuel delivered to the injectors at a constant
pressure and returns excess fuel back to the fuel filter and pump via the fuel cooler.
A fuel filter is positioned on the chassis longitudinal, below the RH rear wheel arch. The fuel feed and return to and
from the engine passes through the filter. The filter also incorporates a water sensor, which illuminates a warning
lamp in the instrument pack.
A moulded fuel tank is located at the rear underside of the vehicle between the chassis longitudinals. The tank
provides the attachment for the fuel pump and the fuel gauge sender unit, which is located inside the tank.
Fuel Tank and Breather
The fuel tank and breather system is a major part of the fuel delivery system. The fuel tank and breathers are
located at the rear of the vehicle between the chassis longitudinals.
Fuel Tank
The moulded fuel tank is made from High Molecular Weight (HMW) High Density Polyethylene (HDPE), and is
manufactured using a proportion of recycled plastic.
The tank is held in position by a metal cradle which is secured to the chassis cross members by four bolts, two
holding the front of the cradle in position, two holding the rear. The fuel tank has a useable capacity of 75 litres
(16.5 gallons).
An aperture in the top surface of the tank allows for the fitment of the fuel pump and fuel gauge sender unit, which
is retained with a locking ring. A reflective metallic covering is attached to the tank with three scrivets to shield the
tank from heat generated by the exhaust system.
Fuel Tank Breather System
The fuel tank filler tube incorporates a tank vent which allows air and fuel vapour displaced from the tank when
filling to vent to atmosphere via the filler neck.
A breather spout within the tank controls the tank’Full’height. When fuel covers the spout it prevents fuel vapour
and air from escaping from the tank. This causes the fuel to’back-up’in the filler tube and shuts off the filler gun.
The position of the spout ensures that when the filler gun shuts off, a vapour space of approximately 10% of the
tanks total capacity remains. The vapour space ensures that the Roll Over Value (ROV) is always above the fuel
level and vapour can escape and allow the tank to breathe.
The ROV is welded to the top surface of the tank. It is connected by a tube to the filler tube, which in turn is
connected to the atmospheric vent pipe. The ROV allows fuel vapour to pass through it during normal vehicle
operation. In the event of the vehicle being overturned the valve shuts off, sealing the tank and preventing fuel
from spilling from the atmospheric vent pipe.
ProCarManuals.com

FUEL SYSTEM
3
DESCRIPTION AND OPERATION FUEL PUMP AND FUEL GAUGE SENDER
1.Fuel burning heater feed pipe (not used)
2.Air bleed connection (natural)
3.HP feed connection (green)
4.LP feed connection (blue)
5.LP return connection (black)
6.Pump feed pipe.
7.Spring
8.Fuel gauge sender unit9.Swirl pot
10.Gauze filter
11.Fuel gauge sender float
12.Electrical connections
13.HP/LP two stage pump
14.Pump LP return pipe
15.Electrical connector
The fuel pump is a self priming, wet type, two stage pump, which is emersed in fuel in the tank. It operates at all
times when the ignition switch is in position’II’. If the engine is not started, the ECM will’time-out’after three
minutes and de-energise the fuel pump relay.
The fuel pump assembly is retained with a locking ring and sealed with a rubber seal. The locking ring requires a
special tool for removal and refitment. The fuel gauge sender is integral with the fuel pump. The sender is
submerged in the fuel and is operated by a float which moves with the fuel level in the tank.
ProCarManuals.com

19FUEL SYSTEM
4
DESCRIPTION AND OPERATION Fuel Pump
The fuel pump assembly comprises a top cover which locates the electrical connector, and four fuel pipe
couplings. The top cover is attached to a plastic cup shaped housing and retained on three sliding clips. Two coil
springs are located between the cover and the housing and ensure that the fuel pump remains seated positively at
the bottom of the tank when installed.
The housing locates the two stage fuel pump and also the fuel gauge sender unit. The lower part of the housing is
the swirl pot which maintains a constant level of fuel at the fuel pick-up. A coarse filter is located in the base of the
housing and prevents the ingress of contaminants into the pump and the fuel system from the fuel being drawn
into the pump. A fine filter is located in the intake to the low pressure stage to protect the pump from
contaminants. Flexible pipes connect the couplings on the top cover to the pump.
A non-return valve is located in the base of the housing. When the fuel tank is full, fuel pressure keeps the valve
lifted from its seat, allowing fuel to flow into the swirl pot. As the tank level reduces, the fuel pressure in the tank
reduces causing the valve to close. When the valve is closed, fuel is retained in the swirl pot, ensuring that the
swirl pot remains full and maintains a constant supply to the fuel pump.
The two stage pump comprises a high and low pressure stage. The low pressure stage draws fuel from the swirl
pot through a filter. The low pressure stage pumps fluid at a pressure of 0.75 bar (10.9 lbf.in) and a flow of 30
litres/hour (8 US Gallons/hour) to the fuel filter. A proportion of the fuel from the low pressure stage also passes,
via a restrictor, through a jet pump which keeps fuel circulating in the swirl pot. The high pressure stage draws the
low pressure fuel from the fuel filter and pressurises it to a pressure of 4.0 bar (58 lbf.in). The pressurised fuel is
then passed from the pump to the injectors at a flow of 180 litres/hour (47.6 US Gallons/hour). A fuel pressure
regulator is located at the rear of the engine and ensures that the delivery pressure remains at 4.0 bar (58 lbf.in)
by controlling the amount of fuel returning to the fuel tank.
The fuel pump has a maximum current draw of 15 Amps at 12 Volts and is supplied a feed (C0114-1) from the fuel
pump relay (C0730-2) on a white/purple wire.
Fuel Gauge Sender
The fuel gauge sender unit comprises a rotary potentiometer operated by a float. The float rises and falls with the
fuel level in the tank and moves the potentiometer accordingly.
A feed is supplied to the fuel gauge sender (C0114-1) by the fuel pump relay (C0730-2) on a purple/white then
white/purple wire. The sender is earthed (C0114-3) on a slate/black wire via header 287. The output voltage
(C0114-2) from the sender to the instrument pack (C1061-3) varies in relation to the fuel level. This output voltage
is connected to the fuel gauge C1054-2). The fuel gauge receives a battery voltage input (C1054-3) on a
white/green wire. This is compared with the output voltage from the potentiometer. The difference between the two
voltages determines the deflection of the fuel gauge pointer.
ProCarManuals.com

FUEL SYSTEM
5
DESCRIPTION AND OPERATION FUEL PRESSURE REGULATOR
NOTE: Non EU3 Model illustrated.
1.Gasket
2.Housing
3.Bolt
4.Fuel feed union and pipe
5.Fuel return union and hose
6.Fuel temperature sensor
7.Bonded seal8.’O’ring
9.Circlip
10.Fuel pressure regulator
11.’O’ring
12.’O’ring
13.Gauze filter
The fuel pressure regulator is located in a cast alloy housing which is attached to the rear right hand corner of the
cylinder head with three flanged bolts and sealed with a metal gasket. Two ports in the housing connect with ports
in the cylinder head for fuel pressure feed and return. A gauze filter is located in the pressure feed port in the
cylinder head, and filters the fuel before it reaches the injectors. The filter is a fit for life item but can be changed if
required. An’O’ring is located in a recess in the cylinder head and provides additional sealing for the pressure
feed port between the gauze filter, the cylinder head, and the housing.
A union and pipe is attached to the feed port in the housing and connects with a quick release coupling to the fuel
pressure feed pipe from the fuel pump. A second union and hose is located in the return port and provides the fuel
return connection to the fuel cooler. A third port provides location for the fuel temperature sensor, which is sealed
to the housing with a bonded seal. The fuel temperature sensor is used by the ECM for engine management.
ProCarManuals.com

FUEL SYSTEM
11
DESCRIPTION AND OPERATION OPERATION
The low pressure stage of the fuel pump draws fuel from the swirl pot and pumps it into the fuel filter. The high
pressure stage of the fuel pump draws the fuel from the fuel filter and pumps it along the fuel feed pipe to the
cylinder head.
The fuel enters the cylinder head through a connection on the fuel pressure regulator housing and supplies each
injector with pressurised fuel. The fuel pressure regulator maintains the fuel pressure at the injectors at 4 bar (58
lbf.in) by returning excess fuel back to the fuel filter. The returned fuel passes through the fuel cooler in the engine
compartment before it passes to the fuel filter.
When the engine is running, each injector is operated by an overhead camshaft which depresses a push rod in
each injector at a timed interval. When the cam has depressed the push rod and the push rod is returning to its
extended position, fuel is drawn from the fuel supply drilling in the injector.
When the ECM determines that injection is required, the ECM transmits an electrical pulse which energises the
fast acting solenoid, closing the spill valve on the injector and locking fuel in the injector body. As the cam begins
to depress the push rod, the fuel in the injector is rapidly pressurised. When the pressure exceeds the nozzle
spring pressure, the nozzle opens and injects fuel at very high pressure into the cylinder.
When the ECM determines that the injection period should end, the solenoid is rapidly de-energised, opening the
spill valve on the injector and allowing fuel to pass into the return circuit.
The ECM controls the injection timing by altering the time at which the solenoid is energised, and the injection
period by controlling the period for which the solenoid is energised.
ProCarManuals.com

FUEL SYSTEM
1
ADJUSTMENT HEATER PLUG TEST
Service repair no - 19.90.20.01
Check
1. Test out of engine
2.Remove heater plug.See Repair.
3.UsingLRT-12-511,connect RED lead to battery
’+’positive and the BLACK lead to battery’-’
negative.
4.Position heater plug into tester and retain with
spring loaded bar.
5.Connect YELLOW lead to heater plug terminal.
6.Press red button on tester and note ammeter
reading. Keep button depressed, heater plug tip
should start to glow after 5 seconds
CAUTION: The heater plug tip must glow
first, if it fails to do so, replace heater plug.
7.The ammeter reading should show an initial
current draw of 25 amps, which should fall to 12
amps after 20 seconds.
8.Refit heater plug.See Repair.FUEL SYSTEM - BLEED
Service repair no - 19.50.07
Fuel Purging Procedure
1.If the vehicle runs out of fuel, or the fuel level is
so low that the fuel system draws air into the fuel
rail, the fuel rail will need to be purged before the
engine will start. This can be achieved by
following a set procedure. The process does not
require the use of any specialist equipment and
can be performed by the driver of the vehicle.
The process is as follows:
2.Switch off ignition and wait 15 seconds.
3.Turn ignition key to position 2 and wait 3
minutes, (this ensures that the fuel system
purges all the air from the fuel rail within the
cylinder head).
4.Depress the throttle pedal to more than 90% of
its total travel, (to the throttle stop).
5.Crank the engine keeping the throttle pedal
depressed.
NOTE: This operation is controlled by the
ECM and it is important that the purging
operation is not carried out on a vehicle
that has not run out of fuel. If it is carried out
unnecessarily it can lead to the engine flooding
and failing to start.
This operation will be cancelled:
6.As soon as engine speed exceeds 600 rev/min.
7.The driver allows the throttle pedal to close to a
position less than 90% of its travel.
8.The ignition key is released from the start
position.
NOTE: The engine must not be cranked for
more than 30 seconds in any one period.
9.Repeat the above procedure if the engine fails to
start.
ProCarManuals.com