Land Rover Defender V8i Workshop Supplement Rover Manual

							19FUEL SYSTEM
2
DESCRIPTION AND OPERATION
1.EVAP purge valve
2.Inertia switch
3.Engine fuel temperature (EFT) sensor
4.Crankshaft position (CKP) sensor
5.Heated oxygen sensor (HO2S) - 2 off
6.Injectors - 8 off
7.Idle air control valve (IACV)
8.Knock sensors - 2 off
9.Intake air temperature (IAT) sensor 
						

							SFI
3
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 for 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 to suit 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.
Crankshaft position (CKP) sensor
The crankshaft position sensor is the most important
sensor on the engine. It is located in the left hand side
of the torque convertor housing. The signal it
produces informs the ECM:
- that the engine is turning
- how fast the engine is turning
- at which stage the engine is, in the combustion
cycle.
As there is no default strategy, failure of the
crankshaft sensor will result in the engine failing to
start.Camshaft position (CMP) sensor
The camshaft position sensor is located in the engine
front cover. It produces four pulses every two
revolutions. The signals are 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.
Mass air flow (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 wire which is heated. Air flows
across the heated wire cooling it and thus changing its
resistance. The ECM measures this change in
resistance, and together with intake air temperature
sensor resistance, 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.
Throttle position (TP) sensor
The throttle position sensor is mounted on the plenum
chamber and connected directly to the throttle shaft.
The sensor is a variable resistor, the signal from
which (0 - 5V) informs the ECM of the actual position
of the throttle disc. As there is no default strategy,
failure of the sensor will result in poor idle and lack of
throttle response. If failure occurs in the closed
position the engine will only reach 1750 rev/min when
the ECM will initiate overrun fuel cut off. 
						

							19FUEL SYSTEM
4
DESCRIPTION AND OPERATION Engine coolant temperature (ECT) sensor
This sensor consists of a temperature dependant
resistive metal strip. The resistance of the strip varies
considerably with coolant temperature, i.e.
- 28K ohms at 30°C (86°F)
- 300 ohms at 85°C (185°F)
- 90 ohms at 130°C (266°F)
The ECT Sensor signal is vital to engine running, as
the correct fuelling is dependant upon engine
temperature i.e. richer mixture at low temperatures. If
the sensor is disconnected or failure occurs a default
value will be supplied to the system. The initial default
value selected will be based on the value of the air
intake temperature. This will increase to a nominal
warmed up value over an individual time, programmed
for each default value. The fault may not be evident to
the driver, though there may be a hot restart problem.
Intake air temperature (IAT) sensor
This is another resistive sensor, located in the body of
the air cleaner. The resistance varies with changes in
air temperature. The signal from the IAT Sensor is
used to retard the ignition timing if the air temperature
rises above 55°C (130°F). If the sensor is
disconnected or failure occurs a default value will be
supplied to the system. The default value selected will
represent normal operating conditions. The fault may
not be evident to the driver, there may be slight power
loss in high ambient temperatures.
Engine fuel temperature (EFT) sensor
The EFT sensor is located on the fuel rail. This sensor
measures temperature of the rail rather than the fuel.
The resistance varies with changes in temperature.
The signal is used to increase the injection pulse time
when undergoing hot restarts. When the fuel is hot,
vapourisation occurs in the rail which may result in the
formation of bubbles in the injectors. Increasing the
pulse time helps flush the bubbles away and cools the
fuel rail with fuel from the tank.
An EFT sensor fault may not be evident to the driver,
there may be a hot restart problem.Knock sensors
The knock sensors produce an output voltage in
proportion to mechanical vibration caused by the
engine. A sensor is located in each cylinder bank
between 2/4 and 3/5 cylinders. The ECM calculates if
the engine is knocking by taking camshaft and
crankshaft sensor signals to determine the position of
the engine in the combustion cycle.
The ECM can also work out exactly which cylinder is
knocking and retards the ignition on that particular
cylinder until the knock disappears. It then advances
the ignition to find the optimum ignition timing for that
cylinder.
The ECM can simultaneously adjust the timing of
each cylinder for knock . It is possible that all eight
cylinders could have different advance angles at the
same time. If the camshaft sensor fails, the knock
sensor will continue to work, but as the engine may be
running one revolution out of sychronisation the ECM
may retard the wrong cylinder of the pair e.g. 1
instead of 6. If the knock sensor fails engine knock will
not be detected and corrected. 
						

							SFI
5
DESCRIPTION AND OPERATION Ignition coils
The electronic ignition system uses four double ended
coils. They are mounted on a bracket fitted to the rear
of the engine. The circuit to each coil is completed by
switching within the ECM, allowing each coil to charge
up and fire. Sparks are produced in two cylinders
simultaneously, one on compression stroke, the other
on exhaust stroke. Note that coil 1 feeds cylinders 1
and 6, coil 2 feeds cylinders 5 and 8, coil 3 feeds
cylinders 4 and 7, and coil 4 feeds cylinders 2 and 3.
The resistance of the spark in the compression
cylinder is higher than that in the exhaust cylinder.
Coil failure will result in a lack of ignition, resulting in
misfire in the affected cylinders.
Injectors
A multiport Sequential Fuel injection (SFI) system is
used, one injector per cylinder. Each injector consists
of a small solenoid which is activated by the ECM to
allow a metered amount of fuel to pass into the
combustion chamber. Due to the pressure in the fuel
rail and the shape of the injector orifice, the fuel
squirts into the cylinder in a fine spray to aid
combustion. In the unlikely event of total injector
failure or leakage which will cause rich mixture, a
misfire will occur in the affected cylinder.
Idle air control (IAC)
Idle speed is controlled by a stepper motor which
consists of two coils. When energised in the correct
sequence the coils move a plunger which opens and
closes the throttle bypass controlling the quantity of
idle air. The stepper motor controls idle speed by
moving the plunger a set distance called a step. Fully
open is 200 steps and fully closed 0 steps. Failure of
the stepper motor will result in low or high idle speed,
poor idle, engine stall or non start.Heated oxygen sensor (HO2S)
The oxygen sensors consist of a titanium metal
sensor surrounded by a gas permeable ceramic
coating. Oxygen in the exhaust gas diffuses through
the ceramic coating on the sensor, and reacts with the
titanium wire altering the resistance of the wire. From
this resistance change the ECM calculates the
amount of oxygen in the exhaust gas. The injected
fuel quantity is then adjusted to achieve the correct
air/fuel ratio, thus reducing the emissions of carbon
monoxide (CO), hydrocarbons (HC),and oxides of
nitrogen (NO
x). Two HO2 sensors are fitted in the
exhaust front pipe, and are positioned behind each
catalyst.
In the event of sensor failure, the system will default to
open loop and fuelling will be calculated using
signals from the remaining ECM inputs.
ECM diagnostics also use HO2 sensors to detect
misfire and fuel system faults. 
						

							19FUEL SYSTEM
6
DESCRIPTION AND OPERATION Fuel pressure regulator
The fuel pressure regulator is a mechanical device
controlled by manifold depression and is mounted at
the rear of the engine in the fuel rail. The regulator
ensures that fuel rail pressure is maintained at a
constant pressure difference to that in the inlet
manifold, as manifold depression increases the
regulated fuel pressure is reduced in direct proportion.
When pressure exceeds the regulator setting excess
fuel is spill returned to the fuel tank swirl pot which
contains the fuel pick-up strainer.
Failure of the regulator will result in a rich mixture at
idle but normal at full load, or a rich mixture resulting
in engine flooding, or a weak mixture.
Relay module
The engine management system employs a relay
module, which houses the main relay and the fuel
pump relay.
Main relay
The main relay supplies the power feed to the ECM
and, the fuel injectors (8 amps) and mass air flow
sensor (4 amps). This relay is controlled by the ECM.
This enables the ECM to remain powered up after
ignition is switched off.
During the ECM power down routine the ECM
records all temperature readings and powers the
stepper motor to the fully open position. Failure of this
relay will result in the ECM not being switched on
resulting in engine not starting due to absence of fuel
and ignition.Fuel pump relay
The fuel pump relay is fed from the ignition relay and
controlled by the ECM. The relay is activated in
ignition key position 2 to prime the fuel system for a
period of time controlled by the ECM. Failure of this
relay will result in no fuel pressure.
Inertia fuel shut-off switch
The inertia switch isolates the power supply to the fuel
pump in the event of sudden deceleration. The inertia
switch is located in the engine compartment. It is reset
by depressing the central plunger at the top of the
switch.
Engine immobilization
A coded signal is sent from the immobilization unit,
located behind the instrument panel, to the vehicle
ECM. If the coded signal does not match the signal
expected by the ECM, the ECM immobilizes the
starting and fuel circuits. 
						

							SFI
1
ADJUSTMENT ENGINE TUNING
Service repair no - 19.22.13
The position of the Idle Air Control (IAC) valve can be
checked using TestBook and adjusted if necessary
through the by-pass screw in the plenum chamber.
The by-pass screw is covered by a tamper proof plug
which can be extracted using a self tapping screw.
All vehicles:
1.Ensure air conditioning and all electical loads are
off. Vehicle must be in neutral or park.
2.Carry out tuning or base idle setting procedure
as applicable using TestBook.
FUEL SYSTEM DEPRESSURISE
Service repair no - 19.50.02
WARNING: Fuel pressure of up to 2.5 bar
(36lbf/in2) 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 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 loosen union.
3.Tighten union to correct torque once pressure is
relieved.
FUEL TANK DRAIN
Service repair no - 19.55.02
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 the 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.
1.Disconnect battery negative lead.
2.Remove fuel filler cap.
3.Using a fuel bowser with an 18 mm (0.75 in)
outside diameter hose, pass hose into tank
through filler neck.
NOTE: Because the fuel tank filler stub
houses a restrictor, repeated attempts may
be necessary to enter the hose into the
fuel tank. Follow the fuel bowser manufacturers
instructions for safe use of bowser.
4.Siphon fuel from fuel tank.
5.Fit filler cap. 
						

							SFI
1
REPAIR IGNITION COILS - SET
Service repair no - 18.20.45
Remove
1.Disconnect battery negative lead.
2.Noting their fitted positions, disconnect 8 h.t.
leads from ignition coils.
3.Move leads aside.
4.Disconnect coil multiplug and release from
mounting bracket.
5.Remove 4 nuts securing coil mounting bracket to
engine.
6.Remove coils and mounting bracket assembly.
Do not carry out further dismantling if
component is removed for access only.
7.Remove terminal cover and note lead positions.
8.Remove 2 nuts securing leads to coil terminals.
9.Remove leads from terminals.
10.Remove 3 Torx screws securing ignition coil to
mounting bracket.
11.Remove ignition coil.12.Fit ignition coil to mounting bracket and secure
with screws.
13.Fit leads to terminals and secure with nuts.
Refit
14.Position coils and mounting bracket assembly to
engine.
15.Fit and tighten nuts securing mounting bracket to
engine to
8 Nm (6 lbf.ft).
16.Connect coil multiplug and secure to mounting
bracket.
17.Connect h.t. leads to ignition coils and fit
terminal cover.
18.Reconnect battery negative lead. 
						

							19FUEL SYSTEM
2
REPAIR ELECTRONIC CONTROL MODULE (ECM)
Service repair no - 18.30.01
Remove
1.Remove screw securing ECM cover.
2.Remove cover.
3.Disconnect 3 multiplugs from ECM.
4.Remove 2 screws securing ECM.
5.Release ECM from 2 lower retainers.
6.Remove ECM.
Refit
7.Position ECM and secure to lower retainers.
8.Fit and tighten screws securing ECM.
9.Connect multiplugs.
10.Fit cover and secure with screw.INTAKE AIR TEMPERATURE (IAT) SENSOR
Service repair no - 18.30.09
Remove
1.Disconnect multiplug from IAT sensor.
2.Remove IAT sensor from air filter housing.
Refit
3.Clean sensor and mating face on filter housing.
4.Fit sensor and tighten to
8 Nm (6 lbf.ft).
5.Connect multiplug. 
						

							SFI
3
REPAIR ENGINE COOLANT TEMPERATURE (ECT)
SENSOR
Service repair no - 18.30.10
Remove
1.Disconnect battery negative lead.
2.Depress 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 to
20 Nm (15 lbf.ft).
9.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.CRANKSHAFT POSITION (CKP) SENSOR
Service repair no - 18.30.12
Remove
1.Disconnect battery negative lead.
2.Raise vehicle on ramp.
3.Remove 2 bolts securing sensor shield to engine
backplate.
4.Release sensor shield.
5.Remove sensor shield.
6.Disconnect multiplug and remove sensor.
7.Remove spacer from sensor.
CAUTION: All vehicles have a spacer fitted
to the sensor. Ensure spacer is correctly
refitted.
Refit
8.Clean mating faces of sensor and engine
backplate.
9.Fit spacer to sensor.
10.Position sensor and connect multiplug.
11.Position shield to sensor and align to engine
backplate.
12.Fit bolts and tighten to
6 Nm (4 lbf.ft).
13.Lower vehicle.
14.Reconnect battery negative lead.