1993 FORD SIERRA spark plugs

manual mixture adjustment is possible.
On models with a catalytic converter, an
evaporative emission control (EVAP) system is
fitted. This prevents the release of fuel vapour
into the atmosphere. With the ignition
switched off, vapours from the fuel tank are
fed to a carbon canister, where they are
absorbed. When the engine is started, the
EEC IV module opens a purge solenoid valve,
and the fuel vapours are fed into the inlet
manifold and mixed with fresh air. This cleans
the carbon filter. A blow-back valve prevents
inlet air being forced back into the fuel tank.
A fuel pump inertia switch is fitted. This
switch breaks the electrical circuit to the fuel
pump in the event of an accident or similar
impact, cutting off the fuel supply to the engine.
A “limited operation strategy” (LOS) means
that the vehicle will still be driveable, albeit at
reduced power and efficiency, in the event of
a failure in the EEC IV module or its sensors.
1.6 and 1.8 litre (R6A type) CVH models
The fuel injection system fitted to these
models is under the overall control of an EEC
IV engine management system which also
controls the ignition timing.
Fuel is supplied from the rear-mounted fuel
tank by an electric fuel pump which is integral
with the fuel level sender unit mounted inside
the fuel tank. Fuel passes via a fuel filter to the
Central Fuel Injection (CFI) unit. A fuel
pressure regulator, mounted on the CFI unit,
maintains a constant fuel pressure to the fuel
injector. Excess fuel is returned from the
regulator to the tank.
The CFI unit, resembling a carburettor,
houses the throttle valve, throttle valve control
motor, throttle position sensor, air charge
temperature sensor, fuel injector, and
pressure regulator.
The duration of the electrical pulse supplied
to the fuel injector determines the quantity of
fuel injected, and pulse duration is computed
by the EEC IV module on the basis of
information received from the various sensors.
The fuel injector receives a pulse twice per
crankshaft revolution under normal operating
conditions, and once per crankshaft
revolution under engine idle conditions. A
ballast resistor is used in the fuel injector
control circuit on 1.6 litre engines.
Inlet air passes through the air cleaner into
the CFI unit. The volume of air entering the
engine is calculated by the EEC IV module from
information supplied by various sensors. These
sensors include the air charge temperature
sensor and throttle position sensor, mounted in
the CFI unit; a crankshaft speed/position
sensor which supplies information on engine
speed; and a manifold absolute pressure (MAP)
sensor which measures the pressure of the air
entering the engine.
Additional sensors inform the EEC IV module
of engine coolant temperature, and vehicle
speed (from a gearbox-mounted sensor).
An exhaust gas oxygen (HEGO) sensor
enables the EEC IV module to control the
fuel/air mixture to suit the operating
parameters of the catalytic converter. No
manual mixture adjustment is possible.
Idle speed is controlled by a throttle valvecontrol motor, which controls the position of
the throttle valve under conditions of idling,
deceleration/part-throttle, and engine start-up
and shut-down.
On 1.6 litre engines, a pulse-air system is
fitted to reduce the exhaust gas emissions
during engine warm-up. The system is con-
trolled by a vacuum-operated valve, which is
operated by the EEC IV module via a solenoid.
The system introduces air into the exhaust
manifold to increase the exhaust gas
temperature, which oxidises more of the
pollutants, and brings the catalyst up to
working temperature more quickly. The
system operates until the catalyst reaches
operating temperature, when the control
solenoid shuts off the system.
On 1.8 litre engines, an exhaust gas
recirculation (EGR) system is used to
recirculate a small amount of exhaust gas into
the inlet manifold. This process lowers the
combustion temperature, resulting in a
reduction of NOx (oxides of nitrogen)
emissions. The EGR system is controlled by
the EEC IV module in conjunction with an
Electronic Pressure Transducer (EPT) and an
Electronic Vacuum Regulator (EVR).
On certain models, an evaporative emission
control system may be fitted. This prevents
the release of fuel vapour into the
atmosphere. With the ignition switched off,
vapours from the fuel tank are fed to a carbon
canister, where they are absorbed. When the
engine is started the EEC IV module opens a
purge solenoid valve, and the fuel vapours are
fed into the inlet manifold and mixed with
fresh air. This cleans the carbon filter. A blow-
back valve prevents inlet air being forced
back into the fuel tank.
A fuel pump inertia switch is fitted. This
switch breaks the electrical circuit to the fuel
pump in the event of an accident or similar
impact cutting off the fuel supply to the engine.
A “limited operation strategy” (LOS) means
that the vehicle will still be driveable, albeit at
reduced power and efficiency, in the event of
a failure in the EEC IV module or its sensors.
Precautions
Many of the procedures in this Chapter
require the removal of fuel lines and
connections which may result in some fuel
spillage. Before carrying out any operation on
the fuel system refer to the precautions given
in “Safety first!” at the beginning of this
Manual and follow them implicitly. Petrol is a
highly dangerous and volatile liquid and the
precautions necessary when handling it
cannot be overstressed.
Residual pressure will remain in the fuel
lines long after the vehicle was last used,
therefore extra care must be taken when
disconnecting a fuel line hose. Loosen any
fuel hose slowly to avoid a sudden release of
pressure which may cause fuel spray. As an
added precaution place a rag over each union
as it is disconnected to catch any fuel which is
forcibly expelled.
Certain adjustment points in the fuel system
(and elsewhere) are protected by
“tamperproof” caps, plugs or seals. The
purpose of such tamperproofing is todiscourage, and to detent, adjustment by
unqualified operators.
In some EEC countries (though not yet in
the UK) it is an offence to drive a vehicle with
missing or broken tamperproof seals. Before
disturbing a tamperproof seal, satisfy yourself
that you will not be breaking local or national
anti-pollution regulations by doing so. Fit a
new seal when adjustment is complete when
this is required by law.
Do not break tamperproof seals on a
vehicle which is still under warranty.
Catalytic converter - precautions
The catalytic converter is a reliable and simple
device which needs no maintenance in itself,
but there are some facts of which an owner
should be aware if the converter is to function
properly for the full service life.
a)DO NOT use leaded petrol in a car
equipped with a catalytic converter the
lead will coat the precious metals,
reducing their converting efficiency and
will eventually destroy the converter.
b)Always keep the ignition and fuel systems
well-maintained in accordance with the
manufacturers schedule, ensure that the
air cleaner filter element, the fuel filter
(where fitted) and the spark plugs are
renewed at the correct interval if the inlet
air/fuel mixture is allowed to become too
rich due to neglect, the unburned surplus
will enter and burn in thecatalytic
converter, overheating the element and
eventually destroying the converter.
c)If the engine develops a misfire, do not
drive the car at all (or at least as little as
possible) until the fault is cured - the
misfire will allow unburned fuel to enter
the converter, which will result in
overheating, as noted above.
d)DO NOT push- or tow-start the car - this
will soak the catalytic converter in
unburned fuel, causing it to overheat when
the engine does start - see b) above.
e)DO NOT switch off the ignition at high
engine speeds - if the ignition is switched
off at anything above idle speed,
unburned fuel will enter the (very hot)
catalytic converter, with the possible risk
of igniting on the element and damaging
the converter.
f)DO NOT use fuel or engine oil additives -
these may contain substances harmful to
the catalytic converter.
g)DO NOT continue to use the car if the
engine burns oil to the extent of leaving a
visible trail of blue smoke - the unburned
carbon deposits will clog the converter
passages and reduce the efficiency; in
severe cases the element will overheat.
h)Remember that the catalytic converter
operates at very high temperatures - hence
the heat shields on the car’s underbody
and the casing will become hot enough to
ignite combustible materials which brush
against it - DO NOT, therefore, park the car
in dry undergrowth, over long grass or
piles of dead leaves.
i)Remember that the catalytic converter is
FRAGILE, do not strike it with tools during
servicing work, take great care when
Fuel and exhaust systems - fuel injection 4B•3
4B

Note: A tachometer and an exhaust gas
analyser will be required to check the idle
mixture on completion. New seals and
retaining clips must be used when refitting the
injectors, and special grease will be required -
see relevant paragraph. If the injectors are
thought to be faulty, it may be worth trying the
effect of a fuel injector cleaning agent before
removing them.
2.0 litre SOHC models
1Disconnect the battery negative lead.
2Disconnect the crankcase ventilation hose
from the air inlet hose, then disconnect the air
inlet hose from the inlet manifold and the
airflow meter.
3Disconnect the HT lead from the coil, then
remove the distributor cap and position the
cap and HT leads clear of the fuel rail
assembly.
4Disconnect the wiring plugs from the idle
speed control valve, the throttle position sensor
and the engine coolant temperature sensor.
5Remove the fuel pressure regulator.
6Unscrew the securing bolt and remove the
throttle return spring bracket. Disconnect the
throttle return spring.7Disconnect the fuel supply hose from the
fuel rail. Be prepared for petrol spillage.
8Disconnect the wiring plugs from the fuel
injectors, noting their locations for use when
refitting.
9Remove the three securing bolts and
withdraw the fuel rail and fuel injectors from
the inlet manifold as an assembly (see
illustrations).
10To remove a fuel injector from the fuel rail,
remove the retaining clip and withdraw the
injector (see illustration).
11Overhaul of the fuel injectors is not
possible, as no spares are available. If faulty,
an injector must be renewed.
12Commence refitting by fitting new seals to
both ends of each fuel injector. Even if only
one injector has been removed, new seals
must be fitted to all four injectors (see
illustration). Coat the seals with silicone
grease to Ford specification ESEM - ICI71 A.
Similarly, renew all four fuel injector retaining
clips.
13Further refitting is a reversal of removal,
ensuring that all hoses, wiring plugs and leads
are correctly connected. When reconnecting
the air inlet hose, make sure that the hose
clips are correctly aligned - see illustration,
Section 15.
14On completion, check and if necessary
adjust the idle mixture.
2.0 litre DOHC models
15Disconnect the battery negative lead.
16If desired, to improve access, disconnectthe wiring from the inlet air temperature
sensor in the inlet manifold. Similarly, the
throttle cable can be moved to one side by
disconnecting the cable from the throttle
linkage. The spark plug HT leads can be
disconnected and moved to one side, noting
their locations and routing to aid refitting.
17Slowly loosen the fuel rail fuel feed union
to relieve the pressure in the system. Be
prepared for fuel spillage, and take adequate
fire precautions.
18Disconnect the fuel feed hose from the
fuel rail (see illustration).
19Disconnect the fuel return hose from the
fuel pressure regulator. Again, be prepared for
fuel spillage.
20Disconnect the vacuum pipe from the top
of the fuel pressure regulator.
21Disconnect the wiring plugs from the fuel
temperature sensor and the fuel injectors,
noting their locations to assist with refitting.
22Unscrew the two securing bolts, and
withdraw the fuel rail.
23Lift the fuel injectors from their locations
in the cylinder head (see illustration).
24Overhaul of the fuel injectors is not
possible, as no spares are available. If faulty,
an injector must be renewed (refer to the note
at the start of this procedure before
condemning an injector).
25Commence refitting by fitting new seals to
both ends of each fuel injector. It is advisable
to fit new seals to all the injectors, even if only
one has been removed. Lubricate the seals
with clean engine oil.
18Fuel injectors - removal and
refitting
Fuel and exhaust systems - fuel injection 4B•9
4B
18.9b . . . and rear securing bolts
18.18 Disconnecting the fuel feed hose
from the fuel rail18.12 Fuel injector with seals removed18.10 Fuel injector retaining clip (A)
18.9a Fuel rail front securing bolt
(arrowed) . . .17.1 Fuel injector ballast resistor location
(arrowed)
Caution: Refer to the
precautions in Section 1 before
proceeding.

together and using them to unscrew the stud
(see illustration). Alternatively, the distributor
can be removed, although this is not
recommended unless absolutely essential.
Recover the gasket. Note that an earth strap
may be located on one of the manifold
securing bolts or studs; where applicable,
note its location as an aid to refitting.
14With the manifold removed, the various
fuel injection system components can be
separated from the manifold with reference to
the relevant Sections of this Chapter.
15Refitting is a reversal of removal, bearing
in mind the following points.
16Renew the gasket, and apply a bead of
sealant at least 5.0 mm (0.2 in) wide around
the central coolant aperture on both sides of
the gasket. Ensure that all mating faces are
clean.17Tighten the manifold securing nuts and
bolts progressively to the specified torque,
where applicable ensuring that the earth strap
is in position.
18Make sure that all hoses, cables, wires
and leads are correctly reconnected. When
reconnecting the air inlet hose, make sure that
the hose clips are correctly aligned, see
illustration, Section 15.
19On completion, refill the cooling system,
adjust the throttle cable and check and if
necessary adjust the idle mixture.
2.0 litre DOHC models
Note:New fuel injector seals must be used on
refitting.
20Disconnect the battery negative lead.
21Partially drain the cooling system.
22Disconnect the coolant hoses from the
thermostat housing and the inlet manifold.
23Disconnect the air inlet hose from the
front of the inlet manifold.
24Disconnect the breather hoses and the
vacuum hoses from the inlet manifold noting
their locations when disconnecting the brake
servo vacuum hose.
25Disconnect the throttle cable from the
throttle linkage (see illustrations).
26Disconnect the HT leads from the spark
plugs, noting their locations to aid refitting,
and move them to one side.
27Disconnect the wiring from the cooling fan
switch, the engine coolant temperature
sensor, and the temperature gauge sender.
28Release the throttle position sensor wiring
connector from the clip under the throttle body,
and separate the two halves of the connector.
29Remove the fuel injectors.
30Check that all relevant wiring, hoses and
pipes have been disconnected, to facilitate
removal of the manifold.
31Unscrew the ten bolts and two nuts
securing the inlet manifold to the cylinder
head, and carefully withdraw the manifold.
Recover the gasket.
32Recover the two plastic spark plug
spacers from the recesses in the cylinder
head (see illustration).
33If desired, the manifold can be dismantled
with reference to the relevant paragraphs of
this Chapter.
34Refitting is a reversal of removal, bearing
in mind the following points.35Ensure that the spark plug spacers are in
position in the cylinder head recesses before
refitting the manifold.
36Renew all gaskets.
37Tighten all manifold securing nuts and
bolts progressively to the specified torque.
38Make sure that all hoses, pipes and wires
are securely reconnected in their original
positions.
39On completion, refill the cooling system.
Check the adjustment of the throttle cable
and if necessary adjust the idle speed and
mixture (as applicable).1.6 and 1.8 litre (R6A type) CVH
models
40Disconnect the battery negative lead.
41Remove the air cleaner assembly.
42Depressurise the fuel system and
disconnect the fuel inlet pipe from the CFI unit.
43Disconnect the fuel return pipe from the
CFI unit. Be prepared for fuel spillage.
44Disconnect the throttle cable from the
linkage on the CFI unit.
45Partially drain the cooling system.
46Disconnect the coolant hoses from the
thermostat housing and, whereapplicable,
the CFI unit.
47Disconnect the vacuum and breather
hoses from the inlet manifold and the CFI unit,
noting their locations.
48Disconnect the wiring from the following
components, according to engine type.
Air charge temperature sensor.
Throttle position sensor.
Fuel pressure regulator/injector.
Throttle valve control motor.
Engine coolant temperature sensor.
Cooling fan switch.
Temperature gauge sender.
49Unbolt the dipstick tube from the inlet
manifold, and withdraw the dipstick and
dipstick tube from the cylinder block.
50Make a final check to ensure that all
relevant wires, hoses and pipes have been
disconnected to facilitate removal of the
manifold.
51Unscrew the seven nuts, or six securing
nuts and the single bolt, securing the inlet
manifold to the cylinder head, then lift the
manifold from the cylinder head. Recover the
gasket.
52If desired, the CFI unit can be removed
from the inlet manifold.
53If necessary, the thermostat and housing
can be removed from the manifold.
54Refitting is a reversal of removal, noting
the following points.
55Ensure that all mating faces are clean, and
renew all gaskets.
56Tighten the manifold nuts (and bolt, where
applicable) progressively to the specified
torque.
57Make sure that all wires, hoses and pipes
are reconnected as noted before removal.
58Top-up the cooling system.
59On completion, turn the ignition on and off
five times to pressurise the system, and check
for fuel leaks.
Fuel and exhaust systems - fuel injection 4B•13
4B
30.25b . . . and the throttle linkage30.32 Removing a spark plug spacer from
the cylinder head recess
30.25a Disconnect the throttle cable from
the securing bracket . . .
30.13 Where necessary use two nuts
locked together (arrowed) to remove the
front inlet manifold stud