2002 LAND ROVER DISCOVERY check engine

ENGINE - V8
OVERHAUL 12-2-73
6.Reference mark main bearing caps to aid
assembly.
7.Remove 10 side bolts securing main bearing
caps to block.
8.Collect 'Dowty' washers from side bolts. Rear
side bolts have Allen heads.
9.Starting at the centre main bearing cap,
progressively loosen, then remove 2 bolts
securing each main bearing cap.
10.Release and remove main bearing caps.
CAUTION: Keep bearing caps, bearings and
bolts in their fitted order.
11.Remove crankshaft.
12.Remove main bearings from cylinder block and
main bearing caps.
13.Remove key from keyway.
14.Remove rear main sealing washers.
Inspect
1.Clean crankshaft journals and bearing
locations in cylinder block.
2.Inspect main bearings for wear and renew if
necessary. Main bearings are available in two
oversizes. If 2nd oversize bearing is being
fitted, it may be necessary to grind thrust
face of centre main bearing to achieve
correct end-float.
lMain bearing 1st oversize = 0.254 mm (0.01
in).
lMain bearing 2nd oversize = 0.508 mm
(0.02 in).3.Check main bearing journals for wear and
scoring. Measure for ovality; taking 3
measurements at 120
° intervals at each end
and at centre of journals.
lJournal diameter - standard = 63.487 to
63.500 mm (2.499 to 2.520 in).
l1st undersize journal = 63.223 to 63.246
mm (2.511 to 2.512 in).
l2nd undersize journal = 62.979 to 62.992
mm (2.509 to 2.510 in).
lJournal width - standard = 26.975 to 27.026
mm (1.061 to 1.064 in).
lMaximum ovality = 0.040 mm (0.002 in)

ENGINE - V8
12-2-74 OVERHAUL
Reassembly
1.Clean main bearing locations in cylinder block
and bearing caps.
2.Clean sealant from rear main bearing cap and
mating faces.
3.Fit key to keyway.
4.Check threads of main bearing cap bolts for
damage, renew bolts in pairs.
5.Lubricate grooved main bearing shells with
clean engine oil and fit to their locations in
cylinder block.
NOTE: Ensure that the flanged bearing is fitted
to the centre position.
6.Lubricate crankshaft journals with clean engine
oil.
7.Position crankshaft in cylinder block.
8.Attach a DTI to front of cylinder block, move
crankshaft rearwards, position stylus of gauge
on end of crankshaft and zero gauge.
9.Move crankshaft forwards, measure and
record end-float obtained.
l Crankshaft end-float = 0.08 to 0.26 mm
(0.003 to 0.01 in).
10.Lubricate plain bearing shells with clean
engine oil and fit to main bearing caps. 11.Fit main bearing caps 1 to 4 only at this stage,
ensuring that they are the correct way round
and in their fitted order.
12.Lightly lubricate threads of main bearing cap
bolts with clean engine oil.
13.Fit main bearing cap bolts but do not tighten at
this stage. Do not fit side bolts at this stage.
14.Fit side seals to rear main bearing cap,
ensuring that seals do not protrude above
bearing cap face.
15.Apply a 3 mm (0.12 in) wide bead of sealant,
Part No. STC 50550 to bearing cap rear mating
faces on cylinder block.
CAUTION: Ensure sealant does not enter
bolt holes.
16.Carefully fit rear main bearing cap assembly, fit
but do not tighten bolts.
CAUTION: Ensure engine oil does not enter
the side bolt holes in the bearing cap.
17.Lubricate 'Dowty' washers with engine oil and
fit to side bolts.
18.Fit but do not tighten side bolts. Rear side
bolts are Allen headed.

EMISSION CONTROL - TD5
17-1-4 DESCRIPTION AND OPERATION
Emission Control Systems
Engine design has evolved in order to minimise the emission of harmful by-products. Emission control systems fitted
to Land Rover vehicles 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 optimum condition.
In addition to emissions improvements through engine design and the application of electronic engine management
systems, special emission control systems are used to limit the pollutant levels developed under certain conditions.
Two main types of additional emission control system are utilised with the Td5 engine to reduce the levels of harmful
emissions released into the atmosphere. These are as follows:
1Crankcase emission control – also known as blow-by gas emissions from the engine crankcase.
2Exhaust gas recirculation – to reduce NO
2 emissions.
Crankcase emission control
All internal combustion engines generate oil vapour and smoke in the crankcase as a result of high crankcase
temperatures and piston ring and valve stem blow-by, a closed crankcase ventilation system is used to vent
crankcase gases back to the air induction system and so reduce the emission of hydrocarbons.
Gases from the crankcase are drawn into the inlet manifold to be burnt in the combustion chambers with the fresh air/
fuel mixture. The system provides effective emission control under all engine operating conditions.
Crankcase gases are drawn through the breather port in the top of the camshaft cover and routed through the breather
hose and breather valve on the flexible air intake duct to be drawn into the turbocharger intake for delivery to the air
inlet manifold via an intercooler.
An oil separator plate is included in the camshaft cover which removes the heavy particles of oil before the crankcase
gas leaves via the camshaft cover port. The rocker cover features circular chambers which promote swirl in the oil
mist emanating from the cylinder head and camshaft carrier. As the mist passes through the series of chambers
between the rocker cover and oil separator plate, oil particles are thrown against the separator walls where they
condense and fall back into the cylinder head via two air inlet holes located at each end of the rocker cover.
The breather valve is a depression limiting valve which progressively closes as engine speed increases, thereby
limiting the depression in the crankcase. The valve is of moulded plastic construction and has a port on the underside
which plugs into a port in the flexible air intake duct. A port on the side of the breather valve connects to the camshaft
cover port by means of a breather hose which is constructed from a heavy-duty braided rubber hose which is held in
place by hose clips. A corrugated plastic sleeve is used to give further protection to the breather hose. The breather
valve is orientation sensitive, and “TOP” is marked on the upper surface to ensure it is mounted correctly.
It is important that the system is airtight so hose connections to ports should be checked and the condition of the
breather hose should be periodically inspected to ensure it is in good condition.

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
17-2-16 DESCRIPTION AND OPERATION
Fuel leak detection system (vacuum type) – NAS only
The advanced evaporative loss control system equipped with a vacuum type, fuel evaporation leak detection
capability is similar to the standard evaporative loss system, but also includes additional components to enable the
engine control module (ECM) to perform a fuel evaporation leak detection test. The system includes an EVAPs
canister and purge valve, and in addition, a canister vent solenoid (CVS) valve and a fuel tank pressure sensor.
The function of the CVS valve is to block the atmospheric vent side of the EVAP canister under the control of the ECM
so that an evaporation system leak check can be performed. The test is carried out when the vehicle is stationary and
the engine is running at idle speed. The system test uses the natural rate of fuel evaporation and engine manifold
depression. Failure of the leak check will result in illumination of the Malfunction Indicator Lamp (MIL).
The fuel evaporation leak detection is part of the On-Board Diagnostics (OBD) strategy and it is able to determine
vapour leaks from holes or breaks greater than 1 mm (0.04 in.) in diameter. Any fuel evaporation system leaks which
occur between the output of the purge valve and the connection to the inlet manifold cannot be determined using this
test, but these will be detected through the fuelling adaption diagnostics.
Fuel leak detection system (positive pressure type) – NAS only
The evaporative loss control system equipped with a positive pressure type, fuel evaporation leak detection capability
is similar to the vacuum type, but it is capable of detecting smaller leaks by placing the evaporation system under the
influence of positive air pressure. The system includes an EVAPs canister and purge valve, and in addition, a leak
detection pump comprising a motor and solenoid valve.
The solenoid valve contained in the leak detection pump assembly performs a similar function to the CVS valve
utilised on the vacuum type pressure test. The solenoid valve is used to block the atmospheric vent side of the EVAP
canister under the control of the ECM so that an EVAP system leak check can be performed. At the same time,
pressurised air from the pump is allowed past the valve into the EVAP system to set up a positive pressure. The test
is carried out at the end of a drive cycle when the vehicle is stationary and the ignition is switched off. The test is
delayed for a brief period (approximately 10 seconds) after the engine is switched off to allow any slosh in the fuel
tank to stabilise. Component validity checks and pressure signal reference checking takes a further 10 seconds before
the pressurised air is introduced into the EVAP system.
During reference checking, the purge valve is closed and the leak detection pump solenoid valve is not energised,
while the leak detection pump is operated. The pressurised air is bypassed through a restrictor which corresponds to
a 0.5 mm (0.02 in) leak while the current consumption of the leak detection pump motor is monitored.
The system test uses the leak detection pump to force air into the EVAP system when the purge valve and solenoid
valves are both closed (solenoid valve energised), to put the evaporation lines, components and fuel tank under the
influence of positive air pressure. Air is drawn into the pump through an air filter which is located in the engine
compartment.
The fuel leak detection pump current consumption is monitored by the ECM while the EVAP system is under pressure,
and compared to the current noted during the reference check. A drop in the current drawn by the leak detection pump
motor, indicates that air is being lost through holes or leaks in the system which are greater than the reference value
of 0.5 mm (0.02 in). An increase in the current drawn by the leak detection pump motor, indicates that the EVAP
system is well sealed and that there are no leaks present which are greater than 0.5 mm (0.02 in).
The presence of leakage points indicates the likelihood of hydrocarbon emissions to atmosphere from the
evaporation system outside of test conditions and the necessity for rectification work to be conducted to seal the
system. Failure of the leak check will result in illumination of the Malfunction Indicator Lamp (MIL).
C0637-9 Fuel tank pressure sensor (NAS vehicles
with vacuum type EVAP system leak
detection only)Output reference 5V
C0637-12 Analogue fuel level (NAS vehicles with
positive pressure type EVAP system leak
detection only)Input Analogue 0 - 5V
C0637-14 Fuel tank pressure sensor (NAS vehicles
with vacuum type EVAP system leak
detection only)Input signal Analogue 0 - 5V
C0637-20 MIL "ON" Output drive Switch to ground Connector / Pin No. Function Signal type Control

EMISSION CONTROL - V8
DESCRIPTION AND OPERATION 17-2-21
Canister Vent Solenoid (CVS) unit – (NAS with vacuum type, fuel evaporation leak detection system only)
1CVS unit
2Mounting bracket
3Spring clips to pipe from EVAP canister
4Harness connector
The canister vent solenoid (CVS) valve is mounted on a slide-on bracket which is riveted to the cruise control bracket
at the right hand side of the engine compartment. The vent pipe from the EVAP canister is connected to a stub pipe
on the CVS unit via a hose and plastic pipe combination. A two-pin connector links to the engine management ECM
via the engine harness for solenoid control; one of the wires is the supply feed from fuse No.2 in the engine
compartment fusebox, the other wire is the valve drive line to the ECM. The solenoid is operated when the ECM
grounds the circuit.
The valve is normally open, allowing any build up of air pressure within the evaporation system to escape, whilst
retaining the environmentally harmful hydrocarbons in the EVAP canister. When the ECM is required to run a fuel
system test, the CVS valve is closed to seal the system. The ECM is then able to measure the pressure in the fuel
evaporative system using the fuel tank pressure sensor.
The ECM performs electrical integrity checks on the CVS valve to determine wiring or power supply faults. The ECM
can also detect a valve blockage if the signal from the fuel tank pressure sensor indicates a depressurising fuel tank
while the CVS valve should be open to atmosphere.

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
2
1
3

EMISSION CONTROL - V8
17-2-26 DESCRIPTION AND OPERATION
Secondary air injection system
The secondary air injection (SAI) system comprises the following components:
lSecondary air injection pump
lSAI vacuum solenoid valve
lSAI control valves (2 off, 1 for each bank of cylinders)
lSAI pump relay
lVacuum reservoir
lVacuum harness and pipes
The secondary air injection system is used to limit the emission of carbon monoxide (CO) and hydrocarbons (HCs)
that are prevalent in the exhaust during cold starting of a spark ignition engine. The concentration of hydrocarbons
experienced during cold starting at low temperatures are particularly high until the engine and catalytic converter
reach normal operating temperature. The lower the cold start temperature, the greater the prevalence of
hydrocarbons emitted from the engine.
There are several reasons for the increase of HC emissions at low cold start temperatures, including the tendency for
fuel to be deposited on the cylinder walls, which is then displaced during the piston cycle and expunged during the
exhaust stroke. As the engine warms up through operation, the cylinder walls no longer retain a film of fuel and most
of the hydrocarbons will be burnt off during the combustion process.
The SAI pump is used to provide a supply of air into the exhaust ports in the cylinder head, onto the back of the
exhaust valves, during the cold start period. The hot unburnt fuel particles leaving the combustion chamber mix with
the air injected into the exhaust ports and immediately combust. This subsequent combustion of the unburnt and
partially burnt CO and HC particles help to reduce the emission of these pollutants from the exhaust system. The
additional heat generated in the exhaust manifold also provides rapid heating of the exhaust system catalytic
converters. The additional oxygen which is delivered to the catalytic converters also generate an exothermic reaction
which causes the catalytic converters to 'light off' quickly.
The catalytic converters only start to provide effective treatment of emission pollutants when they reach an operating
temperature of approximately 250
°C (482°F) and need to be between temperatures of 400°C (752°F) and 800°C
(1472
°F) for optimum efficiency. Consequently, the heat produced by the secondary air injection “afterburning”,
reduces the time delay before the catalysts reach an efficient operating temperature.
The engine control module (ECM) checks the engine coolant temperature when the engine is started, and if it is below
60º C (131
°F), the SAI pump is started. Secondary air injection will remain operational for a period controlled by the
ECM (76 seconds for NAS vehicles, 64 seconds for EU-3 vehicles). The SAI pump operation can be cut short due to
excessive engine speed or load.
Air from the SAI pump is supplied to the SAI control valves via pipework and an intermediate T-piece which splits the
air flow evenly to each bank.
At the same time the secondary air pump is started, the ECM operates a SAI vacuum solenoid valve, which opens to
allow vacuum from the reservoir to be applied to the vacuum operated SAI control valves on each side of the engine.
When the vacuum is applied to the SAI control valves, they open simultaneously to allow the air from the SAI pump
through to the exhaust ports. Secondary air is injected into the inner most exhaust ports on each bank.
When the ECM breaks the ground circuit to de-energise the SAI vacuum solenoid valve, the vacuum supply to the
SAI control valves is cut off and the valves close to prevent further air being injected into the exhaust manifold. At the
same time as the SAI vacuum solenoid valve is closed, the ECM opens the ground circuit to the SAI pump relay, to
stop the SAI pump.
A vacuum reservoir is included in the vacuum line between the intake manifold and the SAI vacuum solenoid valve.
This prevents changes in vacuum pressure from the intake manifold being passed on to cause fluctuations of the
secondary air injection solenoid valve. The vacuum reservoir contains a one way valve and ensures a constant
vacuum is available for the SAI vacuum solenoid valve operation. This is particularly important when the vehicle is at
high altitude.