air filter LAND ROVER DEFENDER 1999 Owner's Manual

EMISSION CONTROL
9
DESCRIPTION AND OPERATION EGR MODULATOR
1.Port to vacuum source (white band)
2.Port to EGR valve (blue band)3.Port to atmosphere via in-line filter (green band)
4.Harness connector
The EGR modulator is located on a plate fixed to the inner RH front wing. The modulator is attached to the plate
by two studs, each with two nuts which secure the assembly to a rubber mounting, which helps reduce noise. The
modulator must be mounted vertically with the two vacuum ports uppermost.
Modulator operation is controlled by a signal from the ECM which determines the required amount of EGR needed
in response to inputs relating to air flow, engine operation, and ambient conditions. The modulator has a two pin
connector at its base to connect it to the ECM via the engine harness.
The modulator features three ports:
The top port is identified by a white band and connects to a T-piece in the vacuum line via a small bore light
brown plastic hose. The two other ports on the T-piece connect to the vacuum line hoses of black vinyl tubing
between the vacuum pump and the brake servo assembly attached to the bulkhead. The vacuum pump end of
the tubing terminates in a rubber elbow, which gives a vacuum tight seal on the suction port of the vacuum
pump. The brake servo end of the tubing terminates with a non-return valve in a plastic housing which plugs
into the front face of the brake servo housing.
The middle port is identified by a blue band, and connects to the suction port on the EGR valve through a small
bore blue plastic hose.
The lower port is identified by a green band and connects to atmosphere through an in-line filter via a small
bore green plastic hose.
The blue and brown vacuum hoses are protected by corrugated plastic sheaths. The ends of the hoses are fitted
with rubber boots to ensure vacuum tight seals at the component ports.
ProCarManuals.com

17EMISSION CONTROL
10
DESCRIPTION AND OPERATION INLET THROTTLE (ILT) MODULATOR
1.Port to vacuum source (white band)
2.Port to ILT valve (blue band)
3.Port to atmosphere via in-line filter (green band)
4.Harness connector (green)
The ILT modulator is located on a plate fixed to the inner wing on the RH side of the engine below the EGR
modulator. The modulator is attached to the plate by two through-studs, each with two nuts which secure the
modulator assembly to a rubber mounting which helps to reduce noise. The modulator must be mounted in the
vertical orientation with the two vacuum ports uppermost.
The modulator operation is controlled by a signal from the ECM which determines the required ratio of exhaust
gas to fresh inlet air needed in response to inputs relating to air flow and engine operating and ambient conditions.
The modulator has a green two-pin connector at its base to connect it to the ECM through the engine harness.
The ILT valve modulator features three ports:
The top port is identified by a white band and connects to a’T’-piece in the vacuum line via a small-bore brown
plastic hose where it is connected in parallel with the vacuum source line to the EGR valve modulator. The two
other ports on the’T’-piece connect vacuum line hoses of black vinyl tubing between the vacuum pump
attached to the alternator and the brake-servo assembly attached to the bulkhead.
The middle port is identified by a blue band and connects to the suction port on the ILT valve through a
small-bore blue plastic hose.
The lower port is identified by a green band and connects to atmosphere through an in-line filter via a green
plastic hose and a three-way connector positioned in-line between the modulators and the filter. The ILT
modulator hose is connected opposite to the two parallel ports at the three-way connector which connect the
vent lines to the EGR valve modulator and the in-line filter. The other port of the in-line filter vents directly to
atmosphere.
The blue and brown vacuum hoses are protected by corrugated plastic sheaths. The ends of the hoses are fitted
with rubber boots to ensure vacuum tight seals at the component ports.
ProCarManuals.com

EMISSION CONTROL
13
DESCRIPTION AND OPERATION IN-LINE AIR FILTER - PRE EU´ u MODELS
1.To modulator vent port
2.Filter element3.To atmosphere
The in-line air filter is placed in the ventilation line from the EGR modulator. The modulator needs to be able to
vent to atmosphere in order to release the vacuum supplied to the EGR valve. The filter prevents contamination
entering the modulator via the vent port which could cause failure. The filter should be periodically changed in
accordance with the recommended service intervals. The filter is attached to the RH inner front wing, and is held
in position by a clamping bracket. The filter must be mounted vertically.
NOTE: EU3 models are not fitted with an in-line air filter. The ventilation line connects directly to
the air cleaner housing, where it vents to atmosphere.
ProCarManuals.com

ENGINE MANAGEMENT SYSTEM
7
DESCRIPTION AND OPERATION SENSOR - MASS AIR FLOW (MAF)
The MAF sensor is located in the intake system between the air filter housing and the turbocharger. The ECM
uses the information generated by the MAF sensor to control exhaust gas recirculation (EGR).
The MAF sensor works on the hot film principal. The MAF sensor has 2 sensing elements contained within a film.
One element is controlled at ambient temperature e.g. 25°C (77°F) while the other is heated to 200°C (360°F)
above this temperature e.g. 225°C (437°F). As air passes through the MAF sensor the hot film will be cooled.
The current required to keep the constant 200°C (360°F) difference provides a precise although non-linear signal
of the air drawn into the engine. The MAF sensor sends a voltage of between 0 and 5 volts to the ECM,
proportional to the mass of the incoming air. This calculation allows the ECM to set the EGR ratio for varying
operating conditions.
Inputs / Outputs
The MAF sensor receives battery voltage (C0149-3) via the ECM on a brown/orange wire. Signal output on a
slate/light green wire from the MAF sensor (C0149-2) to the ECM (C0158-11) is a variable voltage proportional to
the air drawn into the engine. The MAF sensor is provided an earth (C0149-1) via the ECM (C0158-20) on a
pink/black wire.
The MAF sensor can fail or supply an incorrect signal if one or more of the following occurs:
Sensor open circuit.
Short circuit to vehicle supply.
Short circuit to vehicle earth.
Contaminated sensor element.
Damaged sensor element.
Damaged wiring harness.
MAF sensor supplies incorrect signal (due to air leak or air inlet restriction).
In the event of a MAF sensor signal failure any of the following symptoms my be observed:
During driving, engine speed may dip before recovering.
Difficult starting.
Engine stalls after starting.
Delayed throttle response.
EGR inoperative.
Reduced engine performance.
MAF signal out of parameters.
In the event of a MAF sensor failure, the ECM will use a fixed default value from its memory.
ProCarManuals.com

18ENGINE MANAGEMENT SYSTEM
8
DESCRIPTION AND OPERATION SENSOR - AMBIENT AIR PRESSURE AND
TEMPERATURE (AAP)
The AAP sensor is located in the top of the air filter housing. It provides a voltage signal relative to ambient air
pressure to the ECM. The AAP sensor works on the piezo crystal principal. Piezo crystals are pressure sensitive
and will oscillate in accordance to changes in air pressure. The AAP sensor produces a voltage between 0 and 5
volts proportional to the pressure level of the air in the air filter housing. A reading of 0 volts indicates low pressure
and a reading of 5 volts a high pressure. The ECM uses this signal for the following functions.
To maintain manifold boost pressure.
To reduce exhaust smoke emissions while driving at high altitudes.
Control of the EGR system.
Inputs / Outputs
The ECM (C0158-8) supplies the AAP sensor (C0188-3) with a 5 volt feed on a pink/purple wire. The output signal
from the AAP sensor (C0188-2) is sent to the ECM (C0158-10) on a white/yellow wire. The AAP sensor is earthed
(C0188-1) via the ECM (C0158-30) on a pink/black wire.
The AAP sensor can fail, or supply an incorrect signal if one or more of the following occurs:
Sensor open circuit.
Short circuit to vehicle supply.
Short circuit to vehicle earth.
Contaminated sensor element.
Damaged sensor element.
Resistance in wiring harness.
In the event of an AAP sensor signal failure, any of the following symptoms may be observed:
Altitude compensation inoperative (engine will produce black smoke).
Active boost control inoperative.
Turbocharger boost pressure limited to 1 bar (14.5 lbf.in
2).
EGR altitude compensation inoperative.
In the event of a AAP sensor failure, the ECM will use a fixed default value from its memory.
ProCarManuals.com

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

19 - FUEL SYSTEM
CONTENTS
Page
DESCRIPTION AND OPERATION
COMPONENT LOCATION 1...................................................................................
DESCRIPTION 2.....................................................................................................
FUEL PUMP AND FUEL GAUGE SENDER 3........................................................
FUEL PRESSURE REGULATOR 5........................................................................
INJECTORS 7.........................................................................................................
FUEL FILTER 9.......................................................................................................
WATER SENSOR 10..............................................................................................
OPERATION 11......................................................................................................
ADJUSTMENT
HEATER PLUG TEST 1..........................................................................................
FUEL SYSTEM - BLEED 1.....................................................................................
FUEL TANK - DRAIN 2...........................................................................................
REPAIR
ELEMENT - AIR FILTER 1......................................................................................
SENSOR - FUEL TEMPERATURE 1......................................................................
SWITCH - INERTIA - FUEL CUT OFF 2.................................................................
SENSOR - MASS AIR FLOW (MAF) 2....................................................................
SENSOR - COMBINED MAP AND IAT 3................................................................
SENSOR - AMBIENT AIR PRESSURE (AAP) 3.....................................................
ELEMENT - FUEL FILTER 4...................................................................................
COOLER - FUEL 4..................................................................................................
TURBOCHARGER 5...............................................................................................
FILTER ASSEMBLY - AIR 6...................................................................................
INJECTOR - SET 7.................................................................................................
HEATER PLUGS - SET 9.......................................................................................
INTERCOOLER 9...................................................................................................
POTENTIOMETER - THROTTLE 10......................................................................
PUMP - FUEL 10.....................................................................................................
REGULATOR - FUEL PRESSURE 11....................................................................
FUEL TANK 12.......................................................................................................
NECK - FUEL TANK FILLER 14.............................................................................
ProCarManuals.com

FUEL SYSTEM
1
DESCRIPTION AND OPERATION COMPONENT LOCATION
1.HP stage
2.LP stage
3.Filters
4.Jet pump
5.Fuel pump and fuel gauge sender unit
6.LP return connection
7.LP feed connection8.HP feed connection
9.Air bleed connection
10.Fuel filter
11.Water sensor
12.Fuel cooler
13.Fuel pressure regulator
14.Electronic Unit Injectors
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