1995 LAND ROVER DISCOVERY oil

19FUEL SYSTEM
2
DESCRIPTION AND OPERATION REV: 09/95 ENGINE MANAGEMENT SYSTEM COMPONENT
LOCATION - PRE ADVANCED EVAPS
1. Engine control module
2. Ignition coils
3. Fuel pressure regulator
4. Mass air flow sensor
5. Relay module
- Main relay
- Fuel pump relay
6. Engine coolant temperature sensor
7. Camshaft position sensor
8. Throttle position sensor

SFI
5
DESCRIPTION AND OPERATION REV: 09/95 Engine fuel temperature sensor (EFT Sensor)
This is another resistive sensor. Located on the fuel
rail it 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
and bubbles can occur in the injectors. Increasing the
pulse time flushes the bubbles away, and cools the
fuel rail with fuel from the tank. The fault may not be
evident to the driver, there may be a hot restart
problem. The fault is indicated by illumination of the
malfunction indicator light (MIL) on North American
specification vehicles.
Knock sensors
The knock sensor produces 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 due to camshaft and
crankshaft sensor signals regarding the position of the
engine in the 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
adjust the timing of each cylinder for knock
simultaneously. 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. The fault is indicated by
illumination of the malfunction indicator light (MIL) on
North American specification vehicles.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.
Due to the ease of combustion in the cylinder on the
compression stroke, more energy is dissipated in that
cylinder. Coil failure will result in a lack of sparks and
misfire in the affected cylinders. The fault is indicated
by illumination of the malfunction indicator light (MIL)
on North American specification vehicles.
Injectors
A multiport fuel injection system (MFI) 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 injector failure a misfire will occur as
there will be no fuel to the affected cylinder. The fault
is indicated by illumination of the malfunction indicator
light (MIL) on North American specification vehicles.

19FUEL SYSTEM
6
DESCRIPTION AND OPERATION REV: 09/95 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 zero steps and fully closed 180 steps. Failure
of the stepper motor will result in low or high idle
speed, poor idle, engine stall or non start. The fault is
indicated by illumination of the malfunction indicator
light (MIL) on North American specification vehicles.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
2). Two HO2 sensors are fitted, one in
each exhaust downpipe just ahead of the catalyst.
Note that if the wiring to these sensors is crossed, the
vehicle will start and idle correctly until the sensors
reach operating temperature. Then the ECM will read
the signals from them and send one bank of cylinders
very rich and the other very weak. The engine will
misfire, have a rough idle and emit black smoke, with
possible catalyst damage.
In the event of sensor failure, the system will default to
'open loop'. Operation and fuelling will be calculated
using signals from the remaining ECM inputs.
The fault is indicated by illumination of the malfunction
indicator light (MIL). ECM diagnostics also uses HO2
sensors to detect catalyst damage, misfire and fuel
system faults.
North American vehicles have two extra HO2 sensors
mounted one after each catalyst. These are used to
determine whether the catalysts are operating
efficently.
CAUTION: Although robust within the
vehicle environment, HO2 sensors are
easily damaged by dropping, excessive
heat and contamination. Care must be exercised
when working on the exhaust system not to
damage the sensor housing or tip.

19FUEL SYSTEM
8
DESCRIPTION AND OPERATION ADD: 09/95 ENGINE MANAGEMENT SYSTEM COMPONENT
LOCATION - ADVANCED EVAPS
1.Engine control module (ECM)
2.Ignition coils
3.Fuel pressure regulator
4.Mass air flow (MAF) sensor
5.Relay module
- Main relay
- Fuel pump relay
6.Engine coolant temperature (ECT) sensor
7.Camshaft position (CMP) sensor
8.Throttle position (TP) sensor

19FUEL SYSTEM
6
REPAIR 15.Disconnect hose, plug return hose and rail.
Remove cloth.
16.Remove 6 nuts securing fuel rail and ignition coil
bracket to inlet manifold.
17.Release ignition coil bracket from inlet manifold
studs. Place aside.
18.Release fuel rail and injectors from inlet
manifold.
Do not carry out further dismantling if component
is removed for access only.
19.Remove fuel rail and injectors.
20.Remove 2 bolts securing fuel pressure regulator
to fuel rail.
21.Remove pressure regulator assembly.
22.Remove 'O' ring from fuel pressure regulator and
discard.
23.Remove 8 clips securing injectors to fuel rail.
24.Remove injectors from fuel rail.
25.Remove 2 'O' rings from each injector and
discard.Refit
26.Ensure mating surfaces between inlet manifold
and ram pipe housing are clean.
27.Ensure all locations in fuel rail and inlet manifold
are clean.
28.Lubricate and fit new 'O' rings to injectors and
fuel pressure regulator.
29.Fit fuel pressure regulator to fuel rail. Secure
with bolts. Tighten to
10 Nm.
30.Fit injectors to fuel rail. Secure with clips.
31.Position fuel rail to inlet manifold. Engage
injectors, one bank at a time.
32.Position ignition coil bracket on inlet manifold
studs.
33.Secure ignition coil bracket and fuel rail to inlet
manifold with nuts. Tighten to
8 Nm.
34.Remove plugs from fuel feed and return pipes
and rail.
35.Connect hose and tighten clip.
36.Clean feed pipe union and connect fuel feed
pipe to fuel rail. Tighten union to
16 Nm.
37.Connect multiplugs to fuel injectors and fuel
temperature sensor.
38.Remove cloth from inlet manifold.
39.Apply a thin, uniform coating of Loctite 577
sealant to mating face of inlet manifold.
40.Fit ram housing to inlet manifold. Secure with
bolts. Tighten to
24 Nm.
41.Connect purge hose, crankcase breather hose,
servo and pressure regulator vacuum hoses to
ram housing.
42.Fit plenum chamber.
See Plenum Chamber
43.Reconnect battery negative lead.
44.Start engine. Check for leaks around fuel rail and
injectors.

19FUEL SYSTEM
8
REPAIR IGNITION COILS
Service repair no - 18.20.45 - Set
Service repair no - 18.20.43 - Each
Service repair no - 18.20.44 - Extra - Each
Remove
1.Disconnect battery negative lead.
2.Disconnect H.T. leads from ignition coils. Note
positions of leads.
3.Place H.T. leads aside.
4.Disconnect ignition coil multiplug.
5.Remove 4 nuts securing coil bracket.
6.Release ignition coil bracket from inlet manifold
studs.
7.Manoeuvre coil/bracket assembly from behind
plenum chamber and remove.
8.Remove terminal cover. Note lead positions.
9.Remove 2 nuts securing leads to coil terminals.
10.Remove leads from terminals.
11.Remove 3 Torx screws securing ignition coil to
bracket and remove coil.Refit
12.Fit ignition coil to bracket. Secure with screws.
13.Connect leads to terminals. Secure with nuts.
14.Fit terminal cover.
15.Position ignition coil bracket on inlet manifold
studs.
16.Secure fuel rail and ignition coil bracket with
nuts. Tighten to
8 Nm.
17.Connect multiplug.
18.Connect H.T. leads to respective coil towers.
19.Reconnect battery negative lead.

SFI
11
REPAIR FUEL PRESSURE REGULATOR
Service repair no - 19.45.06
Remove
1.Disconnect battery negative lead.
2.Depressurise fuel system.
See Fuel System -
Depressurise
3.Position cloth over fuel feed union, slacken union
to release fuel pressure, then re-tighten union.
4.Release fuel return hose clip. Remove fuel
return hose from regulator connecting pipe.
5.Plug connections.
6.Remove 4 nuts ignition coil bracket to inlet
manifold.
7.Release ignition coil bracket from inlet manifold
studs and place aside.
8.Release regulator connecting pipe from clip.
9.Disconnect vacuum hose from fuel pressure
regulator.
10.Remove 2 bolts securing fuel pressure regulator
to fuel rail.
11.Remove fuel pressure regulator assembly.
12.Remove 'O' ring and spacer ring from fuel
pressure regulator. Discard 'O' ring.
13.Release clip and remove connecting pipe from
regulator.
14.Fit plugs to regulator and rail.

19FUEL SYSTEM
12
REPAIR Refit
15.Ensure locations on fuel pressure regulator and
fuel rail are clean.
16.Fit new spacer ring and 'O' ring to fuel pressure
regulator. Lubricate 'O' ring with silicone grease.
17.Fit pressure regulator assembly to fuel rail.
18.Secure regulator connecting pipe in clip.
19.Secure with bolts. Tighten to
10 Nm.
20.Align ignition coil bracket to inlet manifold studs.
21.Secure ignition coil bracket and fuel rail to inlet
manifold with nuts. Tighten to
8 Nm.
22.Remove plugs.
23.Connect return pipe to regulator connecting pipe.
Secure with clip.
24.Connect vacuum hose to fuel pressure regulator.
25.Remove cloth.
26.Reconnect battery negative lead.
27.Start engine. Check for leaks around fuel
pressure regulator, fuel feed and fuel return
unions.IDLE AIR CONTROL (IAC)
Service repair no - 19.22.54
Remove
1.Disconnect battery negative lead.
2.Disconnect IAC multiplug.
3.Remove 2 bolts securing IAC to plenum.
4.Remove IAC.
5.Remove gasket and discard.
Refit
6.Ensure all mating faces are clean.
7.Using a new gasket, fit IAC to plenum. Secure
with bolts. Tighten to
2.3 Nm.
8.Connect multiplug.
9.Reconnect battery negative lead.