2002 LAND ROVER DISCOVERY ECU

EMISSION CONTROL - TD5
DESCRIPTION AND OPERATION 17-1-11
EU3 models: The exhaust gases are routed from the exhaust manifold through the EGR cooler to the underside of
the EGR valve. The EGR cooler is bolted to the front of the engine cylinder head. An EGR pipe connects the EGR
cooler to the exhaust manifold and is secured by two Allen screws. The two Allen screws fixing the EGR pipe to the
exhaust manifold should be replaced every time the EGR pipe is removed. A second pipe connects the EGR cooler
to the EGR valve; this pipe is secured to the EGR valve by a clip, and to the cooler by two Allen screws.Extreme care
should be exercised when removing and refitting the EGR pipe to avoid damage. When refitting the EGR
cooler, always tighten the pipe connections BEFORE tightening the bolts securing the cooler to the cylinder
head.
When a vacuum is applied to the EGR suction port, it causes a spindle with sealing disc (EGR valve) to be raised,
opening the port at the EGR pipe to allow the recirculated exhaust gas to pass through into the inlet manifold. The
valve is spring loaded so that when the vacuum is removed from the suction port, the valve returns to its rest position
to tightly close the exhaust gas port.
A vacuum is simultaneously applied to the inlet throttle (ILT) valve suction port which causes the butterfly valve in the
inlet manifold to close by means of a spindle and lever mechanism. Closing the butterfly valve limits the supply of
fresh intercooled air entering the inlet manifold and causes a depression within the inlet manifold to create a greater
suction at the open port to the EGR delivery pipe. In this condition a greater mass of recirculated exhaust gas is drawn
into the inlet manifold for use in the combustion process. When the vacuum is released from the ILT valve suction port
a spring returns the butterfly valve to its fully open position.
By controlling the quantities of recirculated exhaust gas and fresh intake air available in the inlet manifold, the
optimum mix for the prevailing engine operating conditions can be maintained which ensures the intake gas to the
combustion chambers will have burning rate properties which will reduce the NO
x emissions to an acceptable level.
Normally, full recirculation is only applicable when the NO
x emissions are most prevalent.

EMISSION CONTROL - TD5
REPAIRS 17-1-13
REPAIRS
Modulator - EGR
$% 17.45.04
There are two types of modulator fitted. System type
1 has a single modulator, and type 2 has a second
modulator (ILT modulator) bolted to the same
mounting plate.
Remove
1.Disconnect vacuum pipe(s) and multiplug(s)
from EGR modulator.
2.Remove 2 nuts and remove EGR modulator.
Refit
1.Position EGR modulator and tighten securing
nuts.
2.Connect vacuum hose(s) and multiplug(s).
Inlet Throttle (ILT) Modulator
$% 17.45.03
Remove
1.Identify the fitted positions of the 3 vacuum
pipes, then disconnect from the ILT modulator
valve.
2.Disconnect multiplug from ILT modulator.
3.Remove 2 nuts securing modulator and remove
ILT modulator from its mountings.
Refit
1.Fit ILT modulator to its mountings, fit the nuts
and tighten to 10 Nm (7 lbf.ft).
2.Connect vacuum pipes to the positions
identified during removal.
3.Connect multiplug to ILT modulator.

EMISSION CONTROL - TD5
17-1-14 REPAIRS
Valve - EGR - Pre EU3 models
$% 17.45.01
On all vehicles up to VIN number 1A736339, the
EGR pipe assembly must be replaced every time the
system is disturbed.
Remove
1.Release turnbuckles and remove battery cover.
2.Disconnect battery earth lead.
3.Remove 3 bolts and remove engine acoustic
cover.
4.Remove cooling fan coupling.

+ COOLING SYSTEM - Td5, REPAIRS,
Fan - viscous.
5.Disconnect vacuum hose(s) from EGR valve.
6.Loosen clip and release air intake from EGR
valve.
7.Remove 4 bolts, release EGR valve from inlet
manifold and discard gasket.
8.Remove 2 bolts and release EGR valve clip
from cylinder head.
9.Remove and discard 2 bolts securing EGR
valve pipe to exhaust manifold. 10.Remove EGR valve assembly.
11.Remove clip and remove pipe from EGR valve.
Refit
1.Clean EGR valve and mating face on pipe.
2.Position pipe to EGR valve and fit retaining clip.
Fit bolt but do not tighten at this stage.
3.Position EGR valve assembly, locate pipe
flange to exhaust manifold, fit new bolts but do
not tighten at this stage.
4.Clean inlet manifold and EGR valve mating
faces.
5.Using new gasket, position EGR valve to inlet
manifold fit bolts and tighten to 10 Nm (7 lbf.ft).
6.Align EGR pipe clip to cylinder head, fit bolts
but do not tighten at this stage.
7.Tighten EGR pipe bolts to correct torque in
following sequence:
lEGR pipe retaining clip bolt 6 Nm (4.5 lbf.ft)
lEGR pipe clip to cylinder head bolts 10 Nm
(7 lbf.ft)
lEGR pipe flange to exhaust manifold bolts
10 Nm (7 lbf.ft)
8.Position air intake hose and tighten clip.
9.Connect vacuum hoses to EGR valve.
10.Fit cooling fan coupling.

+ COOLING SYSTEM - Td5, REPAIRS,
Fan - viscous.
11.Connect battery earth lead.
12.Fit battery cover and secure the fixings.

EMISSION CONTROL - TD5
REPAIRS 17-1-15
Valve - EGR - EU3 models
$% 17.45.01
Remove
1.Release turnbuckles and remove battery cover.
2.Disconnect battery earth lead.
3.Remove 3 bolts and remove engine acoustic
cover.
4.Remove cooling fan coupling.

+ COOLING SYSTEM - Td5, REPAIRS,
Fan - viscous.
5.Disconnect vacuum hose(s) from EGR valve.
6.Loosen clip screw and disconnect air intake
hose from EGR valve.
7.Remove screw and remove clamp securing
EGR pipe to EGR valve.
8.Remove 4 bolts securing EGR valve, remove
valve and discard gasket.
9.Discard EGR pipe gasket.Refit
1.Clean EGR valve and mating faces.
2.Fit new gasket to EGR pipe.
3.Using new gasket, position EGR valve to inlet
manifold fit bolts and tighten to 10 Nm (7 lbf.ft).
4.Fit EGR pipe clamp and tighten screw to 6 Nm
(4.4 lbf.ft).
5.Connect air intake hose to EGR valve and
tighten clip.
6.Connect vacuum hoses to EGR valve.
7.Fit cooling fan coupling.
+ COOLING SYSTEM - Td5, REPAIRS,
Fan - viscous.
8.Fit engine acoustic cover and tighten bolts to
10 Nm (7 lbf.ft).
9.Connect battery earth lead.
10.Fit battery cover and secure the fixings.

EMISSION CONTROL - V8
DESCRIPTION AND OPERATION 17-2-9
Emission Control Systems
Engine design has evolved in order to minimise the emission of harmful by-products. Emission control systems are
fitted to Land Rover vehicles which are designed to maintain the emission levels within the legal limits pertaining for
the specified market.
Despite the utilisation of specialised emission control equipment, it is still necessary to ensure that the engine is
correctly maintained and is in good mechanical order so that it operates at its optimal condition. In particular, ignition
timing has an effect on the production of HC and NO
x emissions, with the harmful emissions rising as the ignition
timing is advanced.
CAUTION: In many countries it is against the law for a vehicle owner or an unauthorised dealer to modify or
tamper with emission control equipment. In some cases, the vehicle owner and/or the dealer may even be
liable for prosecution.
The engine management ECM is fundamental for controlling the emission control systems. In addition to controlling
normal operation, the system complies with On Board Diagnostic (OBD) system strategies. The system monitors and
reports on faults detected with ignition, fuelling and exhaust systems which cause an excessive increase in tailpipe
emissions. This includes component failures, engine misfire, catalyst damage, catalyst efficiency, fuel evaporative
loss and exhaust leaks.
When an emission relevant fault is determined, the fault condition is stored in the ECM memory. For NAS vehicles,
the MIL warning light on the instrument pack will be illuminated when the fault is confirmed. Confirmation of a fault
condition occurs if the fault is still found to be present during the driving cycle subsequent to the one when the fault
was first detected.

+ ENGINE MANAGEMENT SYSTEM - V8, DESCRIPTION AND OPERATION, Description - engine
management.
The following types of supplementary control system are used to reduce harmful emissions released into the
atmosphere from the vehicle:
1Crankcase emission control – also known as blow-by gas emissions from the engine crankcase.
2Exhaust emission control – to limit the undesirable by-products of combustion.
3Fuel vapour evaporative loss control – to restrict the emission of fuel through evaporation from the fuel
system.
4Fuel leak detection system (NAS only) – there are two types of system which may be used to check the
evaporative emission system for the presence of leaks from the fuel tank to purge valve.
aVacuum leak detection test – checks for leaks down to 1 mm (0.04 in.) in diameter.
bPositive pressure leak detection test – utilises a leak detection pump to check for leaks down to 0.5 mm (0.02
in.) in diameter.
5Secondary air injection system (NAS only) – to reduce emissions experienced during cold starting.
Crankcase emission control system
The concentration of hydrocarbons in the crankcase of an engine is much greater than that in the vehicle's exhaust
system. In order to prevent the emission of these hydrocarbons into the atmosphere, crankcase emission control
systems are employed and are a standard legal requirement.
The crankcase ventilation system is an integral part of the air supply to the engine combustion chambers and it is
often overlooked when diagnosing problems associated with engine performance. A blocked ventilation pipe or filter
or excessive air leak into the inlet system through a damaged pipe or a leaking gasket can affect the air:fuel mixture,
performance and efficiency of the engine. Periodically check the ventilation hoses are not cracked and that they are
securely fitted to form airtight connections at their relevant ports.
The purpose of the crankcase ventilation system is to ensure that any noxious gas generated in the engine crankcase
is rendered harmless by complete burning of the fuel in the combustion chamber. Burning the crankcase vapours in
a controlled manner decreases the HC pollutants that could be emitted and helps to prevent the development of
sludge in the engine oil as well as increasing fuel economy.

EMISSION CONTROL - V8
DESCRIPTION AND OPERATION 17-2-19
For NAS vehicles with positive pressure, EVAP system leak detection capability, the atmosphere vent line from the
EVAP canister connects to a port on the fuel leak detection pump via a short, large bore hose which is secured to the
component ports by crimped metal clips at each end. A large bore plastic hose from the top of the leak detection pump
is routed to the RH side of the engine bay where it connects to an air filter canister. Under normal operating conditions
(when the fuel leak detection solenoid valve is not energised), the EVAP canister is able to take in clean air via the
air filter, through the pipework and past the open solenoid valve to allow normal purge operation to take place and
release any build up of EVAP system pressure to atmosphere.
The EVAP system pipes are clipped at various points along the pipe runs and tied together with tie straps at suitable
points along the runs.
The NAS and ROW EVAP canisters are of similar appearance, but use charcoal of different consistency. The ROW
vehicles use granular charcoal of 11 bwc (butane working capacity) and NAS vehicles use pelletised charcoal with a
higher absorption capacity of 15 bwc. All canisters are of rectangular shape and have capacities of 1.8 litres (3 1/8
imp. pts) with purge foam retention.
Purge valve
1Direction of flow indicator
2Inlet port – from EVAP canister
3Outlet port – to inlet manifold
4Integral electrical connector
The EVAP canister purge valve is located in the engine bay at the LH side of the engine intake manifold. The valve
is held in position by a plastic clip which secures the inlet pipe of the purge valve to a bracket mounted at the rear of
the engine compartment. On NAS vehicles with secondary air injection, the purge valve is fixed to a metal bracket
together with the SAI vacuum solenoid valve; the purge valve is fixed to the bracket by two plastic clips.
A nylon pipe connects the outlet of the purge valve to the stub pipe on the plenum chamber via a short rubber hose.
The connector to the plenum chamber is a quick-release type, plastic 90
° female elbow; the connection is covered by
a rubber seal which is held in position on the port stub pipe.
A service port is connected in line between the EVAP canister and the inlet side of the purge valve and is rated at 1
psi maximum regulated pressure. The service port must be mounted horizontally and is located close to the bulkhead
at the rear of the engine bay. The service point is used by dealers for pressure testing using specialist nitrogen test
equipment for localising the source of small leaks.
The purge valve has a plastic housing, and a directional arrow is moulded onto the side of the casing to indicate the
direction of flow. The head of the arrow points to the outlet side of the valve which connects to the plenum chamber.

EMISSION CONTROL - V8
17-2-24 DESCRIPTION AND OPERATION
Leak Detection Pump (NAS vehicles with positive pressure EVAP system leakage test only)
1Harness connector
2Leak detection pump motor
3Atmosphere connection to/from EVAP canister
4Atmosphere connection to/from air filter
5Leak detection pump solenoid valve
The fuel evaporation leak detection pump is mounted forward of the EVAP canister on a bracket fitted beneath the
vehicle on the RH side of the vehicle chassis. The leak detection pump is fixed to the bracket by three screws through
the bottom of the bracket.
A short hose connects between the atmosphere vent port of the EVAP canister and a port at the rear of the fuel
evaporation leak detection pump. The hose is secured to the ports at each end by crimped metal band clips.
An elbowed quick fit connector on the top of the fuel evaporation leak detection pump connects to atmosphere via a
large bore pipe. The pipe is routed along the underside of the vehicle chassis and up into the RH side of the engine
compartment where it connects to an air filter canister.
The leak detection pump incorporates a 3–pin electrical connector. Pin-1 is the earth switched supply to the ECM for
control of the pump solenoid valve. Pin-2 is the earth switched supply to the ECM for the operation of the pump motor.
Pin-3 is the power supply to the pump motor and solenoid valve and is switched on at system start up via the main
relay and fuse 2 in the engine compartment fusebox.
Under normal circumstances (i.e. when the leak detection pump is not operating and the solenoid is not energised),
the EVAP canister vent port is connected to atmosphere via the open solenoid valve.
The pump is operated at the end of a drive cycle when the vehicle is stationary and the ignition is switched off.
M17 0213
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EMISSION CONTROL - V8
DESCRIPTION AND OPERATION 17-2-25
The leak detection pump module contains an integral air by-pass circuit with restrictor (reference-leak orifice) which
is used for providing a reference value for the leak detection test. The restrictor corresponds to an air leak equivalent
to 0.5 mm (0.02 in) diameter. With the solenoid valve open and the purge valve closed, the pump forces pressurised
air through the orifice while the current drawn by the leak detection pump motor is monitored to obtain the reference
value. The orifice must be kept free from contamination, otherwise the reference restriction may appear less than for
a 0.5 mm leak and consequently adversely affect the diagnostic results.
During the leakage test, the solenoid valve is energised, closing the atmosphere vent line between the EVAP canister
and atmosphere and opening a path to the pressurised air supplied from the leak detection pump motor. Air is pumped
into the EVAP system, while the current drawn by the pump motor is monitored. The current drawn during the leakage
test is compared against the value obtained during the reference check, to determine if an EVAP system leak is
present.
The fuel leak detection pump is powered from a 12V supply and operates at a working pressure of 3 kPa.
Air filter – (NAS vehicles with positive pressure leak detection system only)
1Air vents through canister lid
2Air filter canister
3To fuel leak detection pump (EVAP canister
atmosphere vent)
A paper element air filter (40
µm) is located in a plastic canister at the RH side of the engine compartment. The air
filter canister is fixed to the cruise control mounting bracket by a single nut and bolt. A large bore plastic pipe is
connected to a port at the base of the air filter canister and is secured to the port by a short nylon hose and two crimped
metal band clips.
The air filter is used to prevent particulate contaminants down to 40
µm from entering the fuel leak detection pump.
A press-fit lid on top of the canister contains slots to allow the passage of air into and out of the EVAP system.
The bottom end of the paper element is sealed to the canister and is non-serviceable (i.e fit for life). If necessary, the
canister and paper filter must be replaced as a single, complete assembly.
M17 0203
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