2002 LAND ROVER DISCOVERY oil

ENGINE MANAGEMENT SYSTEM - V8
18-2-42 DESCRIPTION AND OPERATION
Cooling fan relay
The cooling fan relay is located in the engine compartment fuse box. It is a four pin normally open relay. The relay
must be energised to drive the cooling fan.
The cooling fan is used to cool both the condenser in which the ATC refrigerant is held and the radiator. This fan is
used especially when the engine is operating at excessively high temperatures. It is also used as a part of the ECM
backup strategy if the ECT fails.
Input/Output
The ECM provides the earth for the relay coils to allow the relay contacts to close and the cooling fan motor to receive
battery voltage. The ECM uses a transistor as a switch to generate an open circuit in the earth path of the relay
windings. When the ECM opens the earth path, the return spring in the relay will pull the contacts apart to shut down
the cooling fan motor drive.
Input to the cooling fan relay switching contacts is via fuse 5 located in the engine compartment fuse box. The relay
coils are supplied with battery voltage from the main relay, also located in the engine compartment fuse box. The earth
path for the relay coils is via pin 31 of the ECM connector C0636. When the relay is energised the output from the
switching contacts is directly to the cooling fan motor.
The cooling fan relay can fail in the following ways:
lRelay open circuit.
lShort circuit to vehicle battery supply.
lShort circuit to vehicle earth.
lBroken return spring.
In the event of a cooling fan relay failure, the cooling fan does not work.

ENGINE MANAGEMENT SYSTEM - V8
DESCRIPTION AND OPERATION 18-2-45
Ignition timing
The ignition timing is an important part of the ECM adaptive strategy. Ignition is controlled by a direct ignition system
using two four-ended coils operating on the wasted spark principle.
When the ECM triggers an ignition coil to spark, current from the coil travels to one spark plug, then jumps the gap at
the spark plug electrodes, igniting the mixture in the cylinder in the process. Current continues to travel along the earth
path (via the cylinder head) to the spark plug negative electrode at the cylinder that is on the exhaust stroke. The
current jumps across the spark plug electrodes and back to the coil completing the circuit. Since it has simultaneously
sparked in a cylinder that is on the exhaust stroke, it has not provided an ignition source there and is consequently
termed 'wasted'.
Conditions
The ECM calculates ignition timing using input from the following:
lCKP sensor.
lKnock sensors (KS).
lMAF sensor.
lTP sensor (idle only).
lECT sensor.
Function
At engine start up, the ECM sets ignition timing dependent on ECT information and starting rev/min from the CKP. As
the running characteristics of the engine change, the ignition timing changes. The ECM compares the CKP signal to
stored values in its memory, and if necessary advances or retards the spark via the ignition coils.
Ignition timing is used by the ECM for knock control.
Knock control
The ECM uses active knock control to prevent possible engine damage due to pre-ignition. This is achieved by
converting engine block noise into a suitable electrical signal that can be processed by the ECM. A major contributing
factor to engine 'knock' is fuel quality, the ECM can function satisfactorily on 91 RON fuel as well as the 95 RON fuel
that it is calibrated for.
Conditions
The ECM knock control system operates as follows:
lHot running engine.
l91 or 95 RON fuel.
Function
The ECM knock control uses two sensors located one between the centre two cylinders of each bank. The knock
sensors consist of piezo ceramic crystals that oscillate to create a voltage signal. During pre-ignition, the frequency
of crystal oscillation increases which alters the signal output to the ECM.
If the knock sensors detect pre-ignition in any of the cylinders, the ECM retards the ignition timing by 3
° for that
particular cylinder. If this action stops the engine knock, the ignition timing is restored to its previous figure in
increments of 0.75
°. If this action does not stop engine knock then the ECM retards the ignition timing a further 3° up
to a maximum of -15
° and then restores it by 0.75° and so on until the engine knock is eliminated.
The ECM also counteracts engine knock at high intake air temperatures by retarding the ignition as above. The ECM
uses the IAT signal to determine air temperature.

ENGINE MANAGEMENT SYSTEM - V8
18-2-46 DESCRIPTION AND OPERATION
Idle speed control
The ECM regulates the engine speed at idling. The ECM uses the idle air control valve (IACV) to compensate for the
idle speed drop that occurs when the engine is placed under greater load than usual. When the throttle is in the rest
position i.e. it has not been pressed, the majority of intake air that the engine consumes comes from the idle air control
valve.
IACV control idle speed
Conditions in which the ECM operates the IACV control idle speed is as follows:
lIf any automatic transmission gears other than P or N are selected.
lIf air conditioning is switched on.
lIf cooling fans are switched on.
lAny electrical loads activated by the driver.
Function
The idle air control valve utilises two coils that use opposing pulse width modulated (PWM) signals to control the
position of a rotary valve. If one of the circuits that supplies the PWM signal fails, the ECM closes down the remaining
signal preventing the idle air control valve from working at its maximum/ minimum setting. If this should occur, the idle
air control valve assumes a default idle position at which the engine idle speed is raised to 1200 rev/min with no load
placed on the engine.
Evaporative emission control
Due to increasing legislation, all new vehicles must be able to limit evaporative emissions (fuel vapour) from the fuel
tank.
The ECM controls the emission control system using the following components:
lEVAP canister.
lPurge valve.
lCanister vent solenoid (CVS) valve – (NAS vehicles with vacuum type EVAP system leak detection capability
only)
lFuel tank pressure sensor – (NAS vehicles with vacuum type EVAP system leak detection capability only)
lFuel leak detection pump – (NAS vehicles with positive pressure type EVAP system leak detection capability
only)
lInterconnecting pipe work.
Refer to Emissions section for operating conditions of evaporative emission systems.

+ EMISSION CONTROL - V8, DESCRIPTION AND OPERATION, Evaporative emission control operation.
On-Board Diagnostics (OBD) - North American Specification vehicles only
The ECM monitors performance of the engine for misfires, catalyst efficiency, exhaust leaks and evaporative control
loss. If a fault occurs, the ECM stores the relevant fault code and warns the driver of component failure by illuminating
the Malfunction Indicator Light in the instrument pack.
On vehicles fitted with automatic gearbox, the ECM combines with the Electronic Automatic Transmission (EAT) ECU
to provide the OBD strategy.
Conditions
If the OBD function of the ECM flags a fault during its operation, it falls into one of the following categories:
lmin = minimum value of the signal exceeded.
lmax = maximum value of the signal exceeded.
lsignal = signal not present.
lplaus = an implausible condition has been diagnosed.

ENGINE MANAGEMENT SYSTEM - V8
REPAIRS 18-2-71
REPAIRS
Spark plugs
$% 18.20.02
Remove
1.Noting their fitted position, disconnect ht leads
from spark plugs.
2.Using a spark plug socket, remove 8 spark
plugs.
Refit
1.Fit terminals to new spark plugs.
CAUTION: Do not attempt to adjust spark
plug gaps.
2.Fit spark plugs and tighten to 25 Nm (18 lbf.ft).
3.Connect ht leads to spark plugs ensuring they
are in the correct position.
Coil - ignition
$% 18.20.45
Remove
1.Remove upper inlet manifold assembly.

+ MANIFOLDS AND EXHAUST
SYSTEMS - V8, REPAIRS, Gasket - inlet
manifold - upper - Without Secondary Air
Injection.
2.Disconnect multiplugs from ignition coils.
3.Release ht leads from rocker covers and
disconnect ht leads from spark plugs.
4.Carefully manoeuvre ignition coil assembly
from between engine and bulkhead.

ENGINE MANAGEMENT SYSTEM - V8
18-2-72 REPAIRS
5.Noting their fitted position disconnect ht leads
from ignition coil.
6.Remove 3 screws securing ignition coil to
support bracket and remove coils.
Refit
1.Position ignition coil to support bracket, fit and
tighten screws.
2.Connect ht leads to ignition coil ensuring they
are in the correct position.
3.Carefully position ignition coil assembly
between engine and bulkhead.
4.Connect ht leads to spark plugs and secure ht
leads to rocker covers.
5.Connect multiplugs to ignition coils.
6.Fit upper inlet manifold assembly.

+ MANIFOLDS AND EXHAUST
SYSTEMS - V8, REPAIRS, Gasket - inlet
manifold - upper - Without Secondary Air
Injection.
Engine control module (ECM)
$% 18.30.01
Remove
1.Release fixings and remove battery cover.
2.Disconnect battery earth lead.
3.Remove fixings securing fascia RH closing
panel, release diagnostic socket RH drive
models, and remove panel.
4.Remove 2 fixings and remove 'A' post lower
trim.

ENGINE MANAGEMENT SYSTEM - V8
18-2-76 REPAIRS
Sensor - camshaft position (CMP)
$% 18.30.24
Remove
1.Release fixings and remove battery cover.
2.Disconnect battery earth lead.
3.Raise front of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
4.Release fixings and remove underbelly panel.
5.Remove engine oil filter.

+ ENGINE - V8, REPAIRS, Filter - oil.
6.Disconnect engine harness from CMP sensor
and release CMP sensor multiplug from
bracket.
7.Remove bolt from clamp securing CMP sensor
to timing gear cover.
8.Remove clamp and CMP sensor. Discard 'O'
ring from CMP sensor.
Refit
1.Ensure CMP sensor is clean, fit new 'O' ring
and sensor to cover.
2.Fit clamp to CMP sensor and tighten bolt to 8
Nm (6 lbf.ft).
3.Fit sensor multiplug to bracket and connect
engine harness to multiplug.
4.Fit engine oil filter.

+ ENGINE - V8, REPAIRS, Filter - oil.
5.Fit underbelly panel and secure with fixings.
6.Lower vehicle and connect battery earth lead.
7.Fit battery cover and secure with fixings.
Knock sensor (KS)
$% 18.30.28
Remove
1.Release fixings and remove battery cover.
2.Disconnect battery earth lead.
3.Raise front of vehicle.
WARNING: Do not work on or under a
vehicle supported only by a jack. Always
support the vehicle on safety stands.
4.Remove fixings securing underbelly panel and
remove panel.
5.Disconnect multiplug from KS.
6.Remove nut securing KS to cylinder block and
remove KS.
Refit
1.Clean mating faces of KS and cylinder block.
2.Fit KS to cylinder block and tighten nut to 22
Nm (16 lbf.ft).
3.Connect multiplug to KS.
4.Fit underbelly panel and secure with fixings.
5.Remove stand(s) and lower vehicle.
6.Connect battery earth lead.
7.Fit battery cover and secure the fixings.

ENGINE MANAGEMENT SYSTEM - V8
REPAIRS 18-2-83
Injectors
$% 19.60.12
Remove
1.Remove upper manifold.

+ MANIFOLDS AND EXHAUST
SYSTEMS - V8, REPAIRS, Gasket - inlet
manifold - upper - Without Secondary Air
Injection.
2.Carefully manoeuvre ignition coil assembly
from between inlet manifold and bulkhead.
3.Position absorbent cloth beneath fuel pipe to
catch spillage.
4.Disconnect fuel feed hose from fuel rail
CAUTION: Always fit plugs to open
connections to prevent contamination.
5.Release injector harness from fuel rail and
disconnect injector multiplugs. 6.Remove 4 bolts securing fuel rail to inlet
manifold.
7.Release injectors from inlet manifold and
remove fuel rail and injectors.
8.Release spring clips securing injectors to fuel
rail and remove fuel injectors.
9.Remove and discard 2 'O' rings from each
injector.
10.Fit protective caps to each end of injectors.
Refit
1.Clean injectors and recesses in fuel rail and
inlet manifold.
2.Lubricate new 'O' rings with silicone grease
and fit to each end of injectors.
3.Fit injectors to fuel rail and secure with spring
clips.
4.Position fuel rail assembly and push-fit each
injector into inlet manifold.

ENGINE MANAGEMENT SYSTEM - V8
18-2-84 REPAIRS
5.Fit bolts securing fuel rail to inlet manifold and
tighten to 9 Nm (7 lbf.ft).
6.Connect fuel feed hose to fuel rail.
7.Connect injector harness multiplugs and
secure to fuel rail.
8.Carefully position ignition coil assembly
between inlet manifold and bulkhead.
9.Fit upper manifold.

+ MANIFOLDS AND EXHAUST
SYSTEMS - V8, REPAIRS, Gasket - inlet
manifold - upper - Without Secondary Air
Injection.
Actuator - cruise control
$% 19.75.05
Remove
1.Release clip and disconnect inner cable from
actuator.
2.Release outer cable from actuator mounting
bracket.
3.Release vacuum hose from actuator.
4.Remove nut, and remove actuator from
mounting bracket.
Refit
1.Position actuator and tighten retaining nut.
2.Connect vacuum hose to actuator.
3.Connect outer cable to mounting bracket.
4.Connect inner cable to actuator.