1989 FORD FIESTA sensor

Engine temperature information is supplied
by the coolant temperature sensor. This
component is an NTC (Negative Temperature
Coefficient) thermistor - that is, a semi-
conductor whose electrical resistance
decreases as its temperature increases. It
provides the EEC IV module with a constantly-
varying (analogue) voltage signal, corre-
sponding to the temperature of the engine
coolant. This is used to refine the calculations
made by the module, when determining the
correct amount of fuel required to achieve the
ideal air/fuel mixture ratio. Inlet air temperature information is supplied
by the inlet air temperature sensor. This
component is also an NTC thermistor - see the
previous paragraph - providing the module with
a signal corresponding to the temperature of air
passing into the engine. This is used to refine
the calculations made by the module, when
determining the correct amount of fuel required
to achieve the ideal air/fuel mixture ratio. A throttle position sensor is mounted on the
end of the throttle valve spindle, to provide
the EEC IV module with a constantly-varying
(analogue) voltage signal corresponding to the
throttle opening. This allows the module to
register the driver’s input when determining
the amount of fuel required by the engine. Road speed is monitored by the vehicle
speed sensor. This component is a Hall-effect
generator, mounted on the transmission’s
speedometer drive. It supplies the module with a
series of pulses corresponding to the vehicle’s
road speed, enabling the module to control
features such as the fuel shut-off on overrun. A manifold absolute pressure sensor
measures inlet manifold vacuum, and supplies
this information to the EEC IV module for
calculation of engine load at any given throttle
position. Where power steering is fitted, a pressure-
operated switch is screwed into the power
steering system’s high-pressure pipe. The
switch sends a signal to the EEC IV module to
reduce engine speed should the power steering
fluid pressure become excessively high. On models with a catalytic converter, the
oxygen sensor in the exhaust system provides
the EEC IV module with constant feedback -
“closed-loop” control - which enables it to
adjust the mixture to provide the best possible
conditions for the catalytic converter to operate. On turbocharged engines, control of the
turbocharger boost pressure is also governed
by the EEC IV module, acting through the
boost control valve. This allows inlet manifold
depression to be applied to the turbocharger
wastegate control. The turbocharger consists of a turbine that
is driven by the exhaust gases, to suck air
through the air filter and to compress it into the
engine. An air-cooled intercooler, mounted
next to the radiator, cools the inlet air (heated
by its passage through the turbocharger); this
increases the density of the compressed
fuel/air mixture entering the engine, thus
improving the engine’s power output.Precautions
Warning: Petrol is extremely
flammable - great care must be
taken when working on any part
of the fuel system. Do not
smoke or allow any naked flames or
uncovered light bulbs near the work area.
Note that gas powered domestic
appliances with pilot flames, such as
heaters, boilers and tumble dryers, also
present a fire hazard - bear this in mind if
you are working in an area where such
appliances are present. Always keep a
suitable fire extinguisher close to the work
area and familiarise yourself with its
operation before starting work. Wear eye
protection when working on fuel systems
and wash off any fuel spilt on bare skin
immediately with soap and water. Note
that fuel vapour is just as dangerous as
liquid fuel; a vessel that has just been
emptied of liquid fuel will still contain
vapour and can be potentially explosive.
Petrol is a highly dangerous and volatile
liquid, and the precautions necessary
when handling it cannot be overstressed. Many of the operations described in this
Chapter involve the disconnection of fuel
lines, which may cause an amount of fuel
spillage. Before commencing work, refer
to the above Warning and the information
in “Safety first” at the beginning of this
manual. When working with fuel system
components, pay particular attention to
cleanliness - dirt entering the fuel system
may cause blockages which will lead to
poor running.
Note: Residual pressure will remain in the fuel
lines long after the vehicle was last used,
when disconnecting any fuel line, it will be
necessary to depressurise the fuel system as
described in Section 2 .
Note: Refer to Section 16 for specific
precautions relating to turbocharged engines.
2 Fuel system -
depressurisation
1
Refer to Part B, Section 2.
3 Fuel lines and fittings -
general information
Refer to Part B, Section 3.
4 Air cleaner assembly and air inlet components - removal
and refitting
1
Note: Air cleaner element renewal and air
cleaner temperature control system checks
(where applicable) are described in Chapter 1.
Air cleaner assembly
1 Disconnect the battery negative (earth) lead
(refer to Chapter 5A, Section 1).
2 If the idle speed control valve is mounted
on the air cleaner, disconnect the multi-plug
and the air bypass hose from the valve.
3 Disconnect the flexible hose between the
air cleaner lid and the air inlet duct or
turbocharger air inlet.
4 Disconnect the crankcase breather hose
from the front of the air cleaner housing.
5 Unclip and remove the air cleaner lid, then
withdraw the element.
6 Remove the two bolts securing the forward
end of the air cleaner housing, free the
rearward end of the housing from its location
and carefully withdraw from the vehicle (see
illustration) .
7 Refitting is a reversal of the removal
procedure.
Air inlet components
8 Disconnect the battery negative (earth) lead
(refer to Chapter 5A, Section 1).
9 If the idle speed control valve is mounted
on the air cleaner, disconnect the multi-plug
and the air bypass hose from the valve (see
illustration) .
10 Disconnect the HT leads from the spark
plugs, labelling them if necessary to avoid
confusion on refitting.
Fuel system - electronic fuel injection engines 4C•3
4.9 General view of the air inlet
components on non-Turbo models
A Air inlet duct
B Air inlet duct securing bolts
C Spark plug HT lead connectors
D Air cleaner lid
E Idle speed control valve multi-plug
F Air bypass hose
4.6 Air cleaner housing attachments A Bolts B Grommet
4C
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8 Fuel tank- removal,
inspection and refitting
3
Proceed as described in Part A, Section 8,
but before disconnecting the battery, relieve
the residual pressure in the fuel system (see
Section 2), and equalise tank pressure by
removing the fuel filler cap.
9 Fuel pump/fuel gauge sender unit - removal and
refitting
3
Refer to Part B, Section 9.
10 Fuel tank ventilation tube -
removal and refitting
3
Refer to Part A, Section 10, but note that on
models with evaporative emission control, the
ventilation tube connects to the combined
roll-over/anti-trickle-fill valve assembly but,
instead of venting to atmosphere, a further
tube runs the length of the vehicle to a carbon
canister in the front right-hand corner of the
engine compartment.
Further information on the evaporative
emission control system is contained in Part E
of this Chapter.
11 Fuel tank filler pipe -
removal and refitting
3
Refer to Part A, Section 11.
12 Fuel cut-off switch -
removal and refitting
1
Refer to Part B, Section 12.
13 Fuel injection system -
checking
3
Refer to Part B, Section 13
14 Fuel injection system components - removal and
refitting
3
Note: Refer to the warning note in Section 1
before proceeding.
Fuel rail and injectors
Note: For simplicity, and to ensure that the
necessary absolute cleanliness on reassembly,
the following procedure describes the removal
of the fuel rail assembly, complete with the
injectors and pressure regulator, so that
the injectors can be serviced individually on a clean work surface. It is also possible to remove
and refit an individual injector, once the fuel
system has been depressurised and the battery
has been disconnected. If this approach is
followed, read through the complete
procedure, and work as described in the
relevant paragraphs, depending on the amount
of preliminary dismantling required. Be careful
not to allow any dirt to enter the system.
1
Relieve the residual pressure in the fuel
system (see Section 2), and equalise tank
pressure by removing the fuel filler cap. Warning: This procedure will
merely relieve the increased
pressure necessary for the engine
to run - remember that fuel will
still be present in the system components,
and take precautions accordingly before
disconnecting any of them.
2 Disconnect the battery negative (earth) lead
(refer to Chapter 5A, Section 1).
3 Disconnect the HT lead connectors from the
spark plugs, and release the leads from their
locating grooves in the air inlet duct. Position
them out of the way. On Turbo models, undo the
two screws and remove the HT lead bracket.
4 Remove the air inlet components as
described in Section 4.
5 Unscrew the retaining nuts and the bolt,
and detach the accelerator cable support
bracket at the throttle housing.
6 Disconnect the wiring connector from the
throttle position sensor.
7 Unscrew the four retaining bolts, and
remove the throttle housing and its mating
face gasket (see illustration) .
8 Disconnect the wiring multi-plug from the
engine coolant temperature sensor and the
inlet air temperature sensor.
9 Disconnect the wiring multi-plugs from the
fuel injectors, then undo the two retaining
bolts and detach the wiring harness from the
fuel rail (see illustrations) .
10 Unscrew the fuel supply pipe at the fuel
rail. Plug the rail and pipe, to prevent further
fuel spillage and the possible ingress of dirt.
11 Disconnect the fuel return and vacuum
pipes from the pressure regulator, and catch
any fuel spillage in a clean cloth.
12 Unscrew the fuel rail securing bolts, and
carefully withdraw the rail (complete with
injectors) from the engine (see illustrations).
Fuel system - electronic fuel injection engines 4C•5
14.9b . . . unbolt the wiring harness . . .
14.9a Disconnect the wiring multi-plug
from each injector . . .14.7 Throttle housing retaining boltlocations (arrowed)
4C
1595Ford Fiesta Remake 14.12a Remove the fuel rail retaining
bolts . . .
14.9c . . . and remove the completeharness
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13Detach the fuel injectors from the fuel rail,
then remove the upper and lower seal from
each injector (see illustration) . All seals must
be renewed (even if only one injector is to be
renewed).
14 Prior to refitting the injectors, ensure that
all mating surfaces are perfectly clean.
Lubricate the new injector seals with clean
engine oil to ease their assembly to the
injectors.
15 Refitting is a reversal of the removal
procedure. Refer to the Specificationsat the
start of this Chapter for the tightening torques.
When refitting the fuel rail, ensure that the
injectors are correctly located. Ensure that the
mating surfaces of the throttle housing are
perfectly clean before assembling.
16 On completion, restart the engine and
check the various fuel connections for any
signs of leaks.
Fuel pressure regulator
17 Relieve the residual pressure in the fuel
system (see Section 2), and equalise tank
pressure by removing the fuel filler cap. Warning: This procedure will
merely relieve the increased
pressure necessary for the
engine to run - remember that
fuel will still be present in the system
components, and take precautions
accordingly before disconnecting any of
them.
18 Disconnect the battery negative (earth)
lead (refer to Chapter 5A, Section 1). 19
Release the fuel return pipe securing clip,
and detach the pipe from the regulator.
20 Pull free the vacuum pipe from the
regulator connector (see illustration).
21 Unscrew the two retaining bolts and
remove the regulator. Remove the old sealing
ring for renewal.
22 Refit in the reverse order of removal.
Lubricate the new seal ring with clean engine oil
to ease assembly. When the regulator is refitted
and the fuel and vacuum lines are reconnected,
turn the ignition on and off five times (without
cranking the engine) and check for any sign of
fuel leaks before restarting the engine.
Idle speed control valve
Note: The idle speed control valve may be
mounted on the air cleaner, on the engine
compartment bulkhead, or on the side of the
inlet manifold according to valve make and
year of manufacture. Valves manufactured by
Weber are mounted on the air cleaner and
require periodic maintenance (see Chapter 1).
Bulkhead and inlet manifold mounted valves
are manufactured by Hitachi and are
maintenance free.
23 Disconnect the battery negative (earth)
lead (refer to Chapter 5A, Section 1).
24 Disconnect the valve’s wiring multiplug
(see illustration) .
25 Where applicable disconnect the air
hose(s) from the valve.
26 Undo the two or four bolts (according to
type), and remove the valve from the air
cleaner, bulkhead or inlet manifold. 27
Refitting is a reversal of the removal
procedure. Ensure that the mating faces are
clean before reassembling.
28 When the valve is refitted, restart the
engine and check that there are no induction
leaks. Run the engine until its normal
operating temperature is reached, and check
that the idle speed is stable. Stop the engine,
connect up a tachometer in accordance with
its maker’s instructions, then restart the
engine and check that the idle speed is as
specified with all electrical items (lights, heater
blower motor, etc) switched off, then on. The
idle speed should remain the same. Switch off
the electrical items, turn the engine off and
detach the tachometer to complete the test.
Throttle housing
29 Disconnect the battery negative (earth)
lead (refer to Chapter 5A, Section 1).
30 Disconnect the ignition HT lead
connectors from the spark plugs, and release
the leads from their locating grooves in the air
inlet duct. Position them out of the way.
31 Remove the air inlet components as
described in Section 4.
32 Unscrew the retaining nuts and the bolt,
and detach the accelerator cable support
bracket at the throttle housing.
33 Disconnect the wiring connector from the
throttle position sensor.
34 Unscrew the four retaining bolts, and
remove the throttle housing and its mating
face gasket (see illustration 14.7) .
35 Refit in the reverse order of removal.
Check that the mating faces are clean, and fit
a new gasket.
EEC IV engine management
module
Note: The module is fragile. Take care not to
drop it, or subject it to any other kind of
impact. Do not subject it to extremes of
temperature, or allow it to get wet. Refer to
Part B, Section 14 for illustrations of the
following procedure.
36 Disconnect the battery negative (earth)
lead (refer to Chapter 5A, Section 1).
37 Unscrew and remove the two nuts
securing the module cover in the engine
compartment, then carefully draw the cover
away from its location. Unscrew the module
multi-plug retaining bolt and disconnect
the multi-plug from the module.
38 The aid of an assistant will be required at
this stage, to support and withdraw the
module from inside the passenger
compartment as its mounting bracket retaining
tags are compressed and released from the
engine compartment. Do not allow the module
to drop into the passenger compartment as
irreparable damage is likely to result. The
module may be separated from its mounting
bracket by undoing the securing bolts.
39 Refitting is a reversal of the removal
procedure, ensuring that the module
mounting bracket retaining tags are felt to
snap into position
4C•6 Fuel system - electronic fuel injection engines
14.24 Disconnect the multi-plug from the idle speed control valve. Upper valve
retaining bolt (arrowed)14.20 Fuel pressure regulator showingvacuum pipe (A) and fuel return pipe
connection (B)
14.13 Remove the seals from the injectors14.12b . . . and withdraw the fuel rail and injectors
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Crankshaft position sensor
40Refer to Chapter 5B.
Coolant temperature sensor
41Refer to Chapter 3.
Inlet air temperature sensor
42Remove the air inlet components as
described in Section 4.
43 Releasing its clip, unplug the sensor’s
electrical connector, then unscrew the sensor
from the inlet manifold (see illustration).
44 Refitting is the reverse of the removal
procedure.
Throttle position sensor
45 Remove the air inlet components as
described in Section 4.
46 Releasing its wire clip, unplug the
sensor’s electrical connector. Remove the
retaining screws, and withdraw the unit from
the throttle housing (see illustration). Do not
force the sensor’s centre to rotate past its
normal operating sweep; the unit will be
seriously damaged.
47 Refitting is the reverse of the removal
procedure, noting the following points (see
illustration) :
a) Ensure that the potentiometer is correctly
orientated, by locating its centre on the D-
shaped throttle shaft (throttle closed), and aligning the potentiometer body so that
the bolts pass easily into the throttle
housing.
b) Tighten the screws evenly and securely
(but do not overtighten them, or the
potentiometer body will be cracked).
Vehicle speed sensor
48 The sensor is mounted at the base of the
speedometer drive cable, and is removed with
the speedometer drive pinion. Refer to the
relevant Section of Chapter 7A or B, as
applicable.
Manifold absolute pressure
sensor
49 The sensor is located near the centre of
the engine compartment bulkhead.
50 Disconnect the wiring multi-plug, and
detach the vacuum hose from the base of the
sensor.
51 Undo the two retaining screws, and
withdraw the sensor from its location.
52 Refitting is the reverse of the removal
procedure.
Power steering pressure switch
53 Releasing its clip, unplug the switch’s
electrical connector, then unscrew the switch
from the power steering high pressure pipe.
Place a wad of rag underneath, to catch any spilt fluid. If a sealing washer is fitted, renew it
if it is worn or damaged.
54
Refitting is the reverse of the removal
procedure; tighten the switch securely, then
top-up the fluid reservoir (see “Weekly
Checks” ) to replace any fluid lost from the
system, and bleed out any trapped air (see
Chapter 10).
Oxygen sensor
Note: The sensor is delicate, and will not work
if it is dropped or knocked, if its power supply
is disrupted, or if any cleaning materials are
used on it.
55 Release the sensor’s wiring multi-plug
from its bracket below the starter motor, and
unplug it to disconnect the sensor.
56 Raise and support the front of the vehicle
if required to remove the sensor from
underneath (“see Jacking and vehicle
support” ). Remove the sensor heat shields
then unscrew the sensor from the exhaust
system front downpipe; collect the sealing
washer (where fitted).
57 On refitting, clean the sealing washer
(where fitted) and renew it if it is damaged or
worn. Apply a smear of anti-seize compound
to the sensor’s threads, to prevent them from
welding themselves to the downpipe in
service. Refit the sensor, tightening it to its
specified torque wrench setting; a slotted
socket will be required to do this. Reconnect
the wiring, and refit the connector plug.
Fuel mixture/CO% adjustment
potentiometer
58 The fuel mixture/CO% adjustment
potentiometer is located on the engine
compartment bulkhead below the ignition
module.
59 Disconnect the battery negative (earth)
lead (refer to Chapter 5A, Section 1).
60 Disconnect the potentiometer’s wiring
multiplug (see illustration) .
61 Unscrew the retaining screw and remove
the potentiometer from the bulkhead.
62 Refitting is the reverse of the removal
procedure.
Fuel system - electronic fuel injection engines 4C•7
14.46 Disconnect the multi-plug from the throttle position sensor. Sensor retaining screws (arrowed)14.43 Disconnecting the intake airtemperature sensor multi-plug
14.60 Fuel mixture/CO% adjustment potentiometer
A Securing screw B Multi-plug14.47 General view of the throttle position sensor and its “D” shaped throttle spindle location (arrowed)
4C
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15 Inlet manifold-
removal and refitting
4
Note: Refer to the warning note in Section 1
before proceeding.
Removal
1 The inlet manifold is a two-piece assembly
comprising an upper and lower section bolted
together (see illustration) .
2 Drain the cooling system with reference to
Chapter 1.
3 Depressurise the fuel system as described
in Section 2.
4 Disconnect the battery negative (earth) lead
(refer to Chapter 5A, Section 1).
5 Remove the air inlet components (Section
4) and disconnect the accelerator cable from
the throttle linkage (Section 5).
6 Remove the fuel injectors and fuel rail as
described in Section 14.
7 Noting their locations, disconnect the
coolant, vacuum and breather hoses from the
manifold.
8 Disconnect the wiring multi-plugs from the
engine sensors at the inlet manifold.
9 Undo the retaining bolts, and withdraw the
manifold from the cylinder head. Note the
location of the engine lifting bracket and earth
lead, where fitted. Remove the gasket.
10 With the manifold removed, clean all
traces of the old gasket from the mating surfaces of the manifold and the cylinder
head.
Refitting
11
Refitting is the reversal of removal. Use a
new gasket, and tighten the retaining bolts to
the specified torque (see illustration).
Refit the remainder of the components with
reference to the appropriate Chapters of this
manual. Refill the cooling system as
described in Chapter 1 on completion.
16 Turbocharger - general
information and precautions
General information
1 A water-cooled turbocharger is used on all
Turbo models covered by this manual. The
turbocharger increases the efficiency of the
engine by raising the pressure in the inlet
manifold above atmospheric pressure.
Instead of the air/fuel mixture being simply
sucked into the cylinders it is actively forced
in.
2 Energy for the operation of the
turbocharger comes from the exhaust gas.
The gas flows through a specially-shaped
housing (the turbine housing) and in so doing
spins the turbine wheel. The turbine wheel is
attached to a shaft, at the other end of which
is another vaned wheel known as the compressor wheel. The compressor wheel
spins in its own housing and compresses the
inducted air on the way to the inlet manifold.
3
After leaving the turbocharger, the
compressed air passes through an
intercooler, which is an air-to-air heat
exchanger mounted with the radiator. Here
the air gives up heat which it acquired when
being compressed. This temperature
reduction improves engine efficiency and
reduces the risk of detonation.
4 Boost pressure (the pressure in the inlet
manifold) is limited by the turbocharger
wastegate control, which diverts the exhaust
gas away from the turbine wheel in response
to the boost control valve. The valve is
controlled by the EEC IV engine management
module.
5 The turbo shaft is pressure-lubricated by
means of a feed pipe from the engine’s main oil
gallery. The shaft “floats” on a cushion of oil. A
drain pipe returns the oil to the sump.
6 Water cooling reduces the operating
temperature of the turbocharger, and in
particular, the shaft bearings. Water continues
to circulate by convection after the engine has
stopped, so cooling the unit if it is hot after a
long run.
Precautions
7 The turbocharger operates at extremely
high speeds and temperatures. Certain
precautions must be observed to avoid
premature failure of the turbo or injury to the
operator. a) Do not operate the turbo with any parts
exposed. Foreign objects falling onto the
rotating vanes could cause extensive
damage and (if ejected) personal injury.
b) Do not race the engine immediately after
start-up, especially if it is cold. Give the oil
a few seconds to circulate.
c) Always allow the engine to return to idle
speed before switching it off - do not blip
the throttle and switch off, as this will
leave the turbo spinning without
lubrication.
d) Allow the engine to idle for several
minutes before switching off after a high-
speed run.
e) Observe the recommended intervals for oil and filter changing, and use a
reputable oil of the specified quality.
Neglect of oil changing, or use of inferior
oil, can cause carbon formation on the
turbo shaft and subsequent failure.
17 Intercooler -
removal and refitting
2
Removal
1 Disconnect the battery negative (earth) lead
(refer to Chapter 5A, Section 1).
2 Remove the flexible hose connecting the
intercooler to the air inlet duct, then the pipe
4C•8 Fuel system - electronic fuel injection engines
15.1 Exploded view of the inlet manifold arrangement
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4D
1595Ford Fiesta Remake
General
System type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . Sequential Electronic Fuel injection (SEFi)
Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . . 1.4 litre PTE engines and 1.6 and 1.8 litre Zetec engines
Fuel grade
Fuel octane requirement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. 95 RON unleaded
Fuel pressure
Regulated fuel pressure:*Pressure regulator vacuum hose disconnected . . . . . . . . . . . . . . . . . 2.7 ± 0.2 bars
With engine running and pressure regulator vacuum hose connected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . 2.1 ± 0.2 bars
Hold pressure - engine stopped after five minutes* . . . . . . . . . . . . . . . . 1.8 bars minimum
*The figures quoted are specific to Zetec engines. No values are quoted \
by the manufacturer for PTE engines, however they are likely to be similar.
Torque wrench settingsNm lbf ft
PTE engines
Inlet air duct to cylinder head cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 7
Inlet manifold to cylinder head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 13
Inlet manifold upper to lower sections . . . . . . . . . . . . . . . . . . . . . . . . . . 18 13
Inlet air temperature sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 11
Fuel rail-to-lower inlet manifold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 17
Camshaft position sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
6 4
Oxygen sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . 60 44
Zetec engines
Throttle housing-to-inlet manifold screws . . . . . . . . . . . . . . . . . . . . . . . 9 7
Inlet manifold to cylinder head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 13
Idle speed control valve bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4
Inlet air temperature sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 11
Fuel pressure regulator bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4
Fuel injector bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . 6 4
Fuel rail-to-inlet manifold bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 7
Camshaft position sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
8 6
Oxygen sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . 60 44
Chapter 4 Part D: Fuel system -
sequential electronic fuel injection engines
Accelerator cable - removal, refitting and adjustment . . . . . . . . . . . 5
Accelerator pedal - removal and refitting . . . . . . . . . . . . . . . . . . . . . 6
Air cleaner assembly and air inlet components - removal and
refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .\
. . . . . . . . . . 4
Air cleaner element renewal . . . . . . . . . . . . . . . . . . . . . .See Chapter 1
Fuel cut-off switch - removal and refitting . . . . . . . . . . . . . . . . . . . . 12
Fuel filter renewal . . . . . . . . . . . . . . . . . . . . . . . . . . \
. . . . .See Chapter 1
Fuel injection system - checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Fuel injection system components - removal and refitting . . . . . . . . 14
Fuel lines and fittings - general information . . . . . . . . . . . . . . . . . . . 3
Fuel pump/fuel gauge sender unit - removal and refitting . . . . . . . . 9 Fuel pump/fuel pressure - checking . . . . . . . . . . . . . . . . . . . . . . . . . 7
Fuel system - depressurisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Fuel tank - removal, inspection and refitting . . . . . . . . . . . . . . . . . . . 8
Fuel tank filler pipe - removal and refitting . . . . . . . . . . . . . . . . . . . . 11
Fuel tank ventilation tube - removal and refitting . . . . . . . . . . . . . . . 10
General fuel system checks . . . . . . . . . . . . . . . . . . . . . .See Chapter 1
General information and precautions . . . . . . . . . . . . . . . . . . . . . . . . 1
Inlet manifold - removal and refitting . . . . . . . . . . . . . . . . . . . . . . . . 15
Underbody fuel/brake line check . . . . . . . . . . . . . . . . . . .See\
Chapter 1
Underbonnet check for fluid leaks and hose condition . .See Chapter 1
4D•1
Specifications Contents
Easy,
suitable for
novice with little
experience Fairly easy,
suitable
for beginner with
some experience Fairly difficult,
suitable for competent
DIY mechanic
Difficult,
suitable for
experienced DIY
mechanic Very difficult,
suitable for expert DIY
or professional
Degrees of difficulty
54321
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1 General information andprecautions
General information
The fuel system consists of a fuel tank
(mounted under the body, beneath the rear
seats), fuel hoses, an electric fuel pump
mounted in the fuel tank, and a sequential
electronic fuel injection system.
The electric fuel pump supplies fuel under
pressure to the fuel rail, which distributes fuel
evenly to all injectors. A pressure regulator
controls the system pressure in relation to
inlet tract depression. From the fuel rail, fuel is
injected into the inlet ports, just above the
inlet valves, by four fuel injectors. The system
also includes features such as the flushing of
fresh (ie, cold) fuel around each injector on
start-up, thus improving hot starts. The amount of fuel supplied by the injectors
is precisely controlled by the EEC IV engine
management module. The module uses the
signals derived from the crankshaft position
sensor and the camshaft position sensor, to
trigger each injector separately in cylinder
firing order (sequential injection), with benefits
in terms of better fuel economy and lower
exhaust emissions. The EEC IV module is the heart of the entire
engine management system, controlling the
fuel injection, ignition and emissions control
systems. The module receives information
from various sensors which is then computed
and compared with pre-set values stored in
it’s memory, to determine the required period
of injection. Information on crankshaft position and
engine speed is generated by a crankshaft
position sensor. The inductive head of the
sensor runs just above the engine flywheel
and scans a series of 36 protrusions on the
flywheel periphery. As the crankshaft rotates,
the sensor transmits a pulse to the system’s
ignition module every time a protrusion
passes it. There is one missing protrusion in
the flywheel periphery at a point
corresponding to 90° BTDC. The ignition
module recognises the absence of a pulse
from the crankshaft position sensor at this
point to establish a reference mark for
crankshaft position. Similarly, the time interval
between absent pulses is used to determine
engine speed. This information is then fed to
the EEC IV module for further processing. The camshaft position sensor is located in
the cylinder head so that it registers with a
lobe on the camshaft. The camshaft position
sensor functions in the same way as the
crankshaft position sensor, producing a series
of pulses; this gives the EEC IV module a
reference point, to enable it to determine the
firing order, and operate the injectors in the
appropriate sequence. The mass air flow sensor is based on a “hot-
wire” system, sending the EEC IV module a constantly-varying (analogue) voltage signal
corresponding to the mass of air passing into
the engine. Since air mass varies with
temperature (cold air being denser than warm),
measuring air mass provides the module with
a very accurate means of determining the
correct amount of fuel required to achieve the
ideal air/fuel mixture ratio.
Engine temperature information is supplied by
the coolant temperature sensor. This
component is an NTC (Negative Temperature
Coefficient) thermistor - that is, a semi-
conductor whose electrical resistance
decreases as its temperature increases. It
provides the EEC IV module with a constantly-
varying (analogue) voltage signal, corresponding
to the temperature of the engine coolant. This is
used to refine the calculations made by the
module, when determining the correct amount
of fuel required to achieve the ideal air/fuel
mixture ratio. Inlet air temperature information is supplied
by the inlet air temperature sensor. This
component is also an NTC thermistor - see
the previous paragraph - providing the
module with a signal corresponding to the
temperature of air passing into the engine.
This is used to refine the calculations made by
the module, when determining the correct
amount of fuel required to achieve the ideal
air/fuel mixture ratio. A throttle position sensor is mounted on the
end of the throttle valve spindle, to provide
the EEC IV module with a constantly-varying
(analogue) voltage signal corresponding to the
throttle opening. This allows the module to
register the driver’s input when determining
the amount of fuel required by the engine.
Road speed is monitored by the vehicle
speed sensor. This component is a Hall-effect
generator, mounted on the transmission’s
speedometer drive. It supplies the module
with a series of pulses corresponding to the
vehicle’s road speed, enabling the module to
control features such as the fuel shut-off on
overrun.
Where power steering is fitted, a pressure-
operated switch is screwed into the power
steering system’s high-pressure pipe. The
switch sends a signal to the EEC IV module to
reduce engine speed should the power
steering fluid pressure become excessively
high.
The oxygen sensor in the exhaust system
provides the module with constant feedback -
“closed-loop” control - which enables it to
adjust the mixture to provide the best possible
conditions for the catalytic converter to
operate. The air inlet side of the system consists of
an air cleaner housing, the mass air flow
sensor, an inlet hose and duct, and a throttle
housing. The throttle valve inside the throttle housing
is controlled by the driver, through the
accelerator pedal. As the valve opens, the
amount of air that can pass through the
system increases. As the throttle valve opens further, the mass air flow sensor signal alters,
and the EEC IV module opens each injector
for a longer duration, to increase the amount
of fuel delivered to the inlet ports.
Both the idle speed and mixture are under
the control of the EEC IV module, and cannot
be adjusted. Not only can they not be
adjusted, they cannot even be checked,
except with the use of special Ford diagnostic
equipment.
Precautions
Warning: Petrol is extremely
flammable - great care must be
taken when working on any part
of the fuel system. Do not
smoke or allow any naked flames or
uncovered light bulbs near the work area.
Note that gas powered domestic
appliances with pilot flames, such as
heaters, boilers and tumble dryers, also
present a fire hazard - bear this in mind if
you are working in an area where such
appliances are present. Always keep a
suitable fire extinguisher close to the work
area and familiarise yourself with its
operation before starting work. Wear eye
protection when working on fuel systems
and wash off any fuel spilt on bare skin
immediately with soap and water. Note
that fuel vapour is just as dangerous as
liquid fuel; a vessel that has just been
emptied of liquid fuel will still contain
vapour and can be potentially explosive.
Petrol is a highly dangerous and volatile
liquid, and the precautions necessary
when handling it cannot be overstressed. Many of the operations described in this
Chapter involve the disconnection of fuel
lines, which may cause an amount of fuel
spillage. Before commencing work, refer
to the above Warning and the information
in “Safety first” at the beginning of this
manual. When working with fuel system
components, pay particular attention to
cleanliness - dirt entering the fuel system
may cause blockages which will lead to
poor running.
Note: Residual pressure will remain in the fuel
lines long after the vehicle was last used,
when disconnecting any fuel line, it will be
necessary to depressurise the fuel system as
described in Section 2 .
2 Fuel system-
depressurisation
1
Refer to Part B, Section 2.
3 Fuel lines and fittings -
general information
Refer to Part B, Section 3.
4D•2 Fuel system - sequential electronic fuel injection engines
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4 Air cleaner assembly and airinlet components - removal
and refitting
1
Air cleaner assembly
1 Disconnect the battery negative (earth) lead
(refer to Chapter 5A, Section 1).
2 Disconnect the mass air flow sensor wiring
multi-plug, then release the clips and
withdraw the sensor, complete with inlet
hose, from the air cleaner cover (see
illustrations) . Carefully position the mass air
flow sensor and hose assembly to one side.
3 Detach the fresh air inlet duct from the air
cleaner housing.
4 Unscrew the air cleaner housing retaining
nut, then pull the housing upwards to release
the locating pegs from their rubber grommets.
As the housing is withdrawn, detach the
crankcase breather hose (see illustration).
Remove the assembly from the car.
5 Refitting is the reverse of the removal
procedure. Ensure that the housing pegs seat
fully in their grommets, and that the mass air
flow sensor is correctly located.
Air inlet components
6 On PTE engines, disconnect the HT leads
from the spark plugs, labelling them if
necessary to avoid confusion on refitting.
7 Slacken the hose clip, and detach the flexible air inlet hose from the mass air flow
sensor.
8
On PTE engines, disconnect the ventilation
hose from the inlet duct over the top of the
engine.
9 On PTE engines undo the two inlet duct
retaining bolts; On Zetec engines , undo the
two bolts and lift off the air inlet duct retaining
strap (see illustration) . Withdraw the inlet
duct from the throttle housing and remove the
duct and flexible hose from the engine.
10 Refitting is the reverse of the removal
procedure.
5 Accelerator cable - removal,
refitting and adjustment
1
Removal
1 Disconnect the battery negative (earth) lead
(refer to Chapter 5A, Section 1).
2 Fold back the carpet and insulation in the
driver’s footwell to gain access to the
accelerator pedal.
3 Detach the accelerator cable from the
pedal.
4 From within the engine compartment,
detach the outer cable from the
adjuster/support bracket by removing the
metal retaining clip (see illustration).5
Pivot the throttle quadrant by hand, detach
the inner cable nipple from the throttle lever
and remove the cable.
Refitting
6 Refit in the reverse order of removal. When
the cable is reconnected at each end, adjust
the cable as follows.
Adjustment
7 Remove the outer cable metal retaining clip
at the adjuster/support bracket and lubricate
the cable adjuster grommet with soapy water.
8 Remove any slack by pulling the cable
outer as far as possible out of the adjuster.
Have an assistant depress the accelerator
pedal fully - the cable outer will move back
into the adjuster - and hold it there while the
clip is refitted.
9 Check that the throttle quadrant moves
smoothly and easily from the fully-closed to
the fully-open position and back again as the
assistant depresses and releases the
accelerator pedal. Re-adjust the cable if
required.
6 Accelerator pedal -
removal and refitting
1
Refer to Part A, Section 5.
Fuel system - sequential electronic fuel injection engines 4D•3
4.2c . . . and withdraw the sensor4.2b . . . release the retaining clips . . .4.2a Disconnect the mass air flow sensor
wiring multi-plug . . .
5.4 Detach the accelerator outer cableretaining clip (arrowed)4.9 Unscrew the nuts (arrowed) to releasethe air intake duct on Zetec engines4.4 Unscrew front retaining nut and lift theair cleaner housing, disconnecting the
breather hose (arrowed)
4D
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