1992 FORD SIERRA spark plugs

sprocket bolt. Note that there is no need to
remove the timing belt or the sprockets.
Note: During production the engine ignition
timing is accurately set using a microwave
process, and sealant is applied to the
distributor clamp bolt. Removal of the
distributor should be avoided except where
excessive bearing wear has occurred due to
high mileage or during major engine overhaul.
A timing light will be required to check the
ignition timing after refitting the distributor.
All models except early
“Economy”
Removal
1Disconnect the battery negative lead.
2If necessary, identify each HT lead for
position, so that the leads can be refitted to
their correct cylinders, then disconnect the
leads from the spark plugs by pulling on the
connectors, not the leads.
3Where applicable, unclip the screening can
from the top of the distributor and disconnect
the earth strap. On fuel injection models,
disconnect the crankcase ventilation hose
from the air inlet hose, then disconnect the air
inlet hose from the inlet manifold and the
airflow meter for improved access.4Prise away the spring clips with a
screwdriver, or remove the two securing
screws, as applicable, and lift off the
distributor cap.
5Disconnect the HT lead from the coil by
pulling on the connector, not the lead, then
slide the HT lead holder from the clip on the
camshaft cover, and withdraw the distributor
cap.
6Where applicable, disconnect the vacuum
pipe from the vacuum advance unit on the
side of the distributor (see illustration).
7Using a suitable socket or spanner on the
crankshaft pulley bolt, turn the crankshaft to
bring No 1 cylinder to the firing point. If the
distributor cap is secured by clips, make sure
that the clips stay clear of the distributormoving parts. No 1 cylinder is at the firing
point when:
a)The relevant timing marks are in
alignment.
b)The tip of the rotor arm is pointing to the
position occupied by the No 1 cylinder HT
lead terminal in the distributor cap. Note
that the position of No 1 HT lead terminal
is identified by a pip or a number “1”
c)On Lucas distributors, the cut-out in the
trigger vane is aligned with the sensor
(see illustration)
d)On Bosch distributors, the tip of the rotor
arm is aligned with the scribed line on the
distributor body (where applicable,
remove rotor arm and dust cover, then
refit rotor arm to check alignment with
scribed line) (see illustration)
e)On Motorcraft distributors, the tip of the
rotor arm is aligned with a notch in the
distributor body. Mark the relevant notch
(there may be several) for reference when
refitting. Also, the leading edge of one of
the trigger vane segments is aligned with
the rib on the sensor (remove the two
securing screws and lift off the rotor arm
to view the trigger vane and sensor) (see
illustration).
8Disconnect the distributor wiring plug,
where applicable depressing the locking
tab(s). Pull on the plug, not the wiring (see
illustration).
9Make alignment marks between the
distributor body and the cylinder block.
10Scrape the sealant from the distributor
clamp bolt, then unscrew and remove the bolt
and clamp (see illustration).
11Withdraw the distributor from the cylinder
block. As the distributor is removed, the rotor
arm will turn clockwise due to the skew gear
drive. Note the new position of the rotor arm
relative to the distributor body, if necessary
making an alignment mark (some distributors
already have an alignment mark).
12Check the distributor spindle for
excessive side-to-side movement. If evident,
the distributor must be renewed, as the only
spares available are the cap, rotor arm,
module (where applicable), and driveshaft
O-ring (see illustration).
15Distributor (OHC models) -
removal and refitting
5•16Engine electrical systems
14.9 Removing the rotor housing
15.7a Lucas distributor showing trigger
vane position No 1 cylinder at firing point
A Trigger vane cut
-outB Sensor
15.8 Disconnecting distributor wiring plug
- Bosch distributor15.7c Trigger vane segment leading edge
aligned with sensor rib - Motorcraft
distributor15.7b Rotor arm tip aligned with scribed
line on distributor body - Bosch distributor
15.6 Disconnecting vacuum pipe from
vacuum advance unit - Bosch distributor

Refitting
13Commence refitting by checking that No 1
cylinder is still at the firing point. The relevant
timing marks should be aligned. If the engine
has been turned whilst the distributor has
been removed, check that No 1 cylinder is on
its firing stroke by removing the No 1 cylinder
spark plug and placing a finger over the plug
hole. Turn the crankshaft until compression
can be felt, which indicates that No 1 piston is
rising on its firing stroke. Continue turning the
crankshaft until the relevant timing marks are
in alignment.
14Turn the rotor arm to the position noted in
paragraph 11. If a new distributor is being
fitted, and no alignment marks are present,
transfer the marks from the old distributor to
the new distributor.
15Hold the distributor directly over the
aperture in the cylinder block with the
previously made marks on the distributor
body and cylinder block aligned, then lower
the distributor into position. Again, if a new
distributor is being fitted, transfer the
alignment mark from the old distributor body
to the new distributor body. As the skew gear
drive meshes, the rotor arm will turn
anti-clockwise.
16With the distributor fitted and the marks
on the distributor body and cylinder block
aligned, check that the rotor arm is positioned
as described in paragraph 7 -if not, withdraw
the distributor, re-position the driveshaft and
try again.
17Refit the clamp, then insert and tighten
the bolt. Do not fully tighten the bolt at this
stage.
18Refit the distributor wiring plug, and
where applicable reconnect the vacuum pipe,
and refit the dust cover and/or rotor arm.
19Refit the distributor cap, and reconnect
the HT leads to the spark plugs and coil.
Ensure that the leads are refitted to their
correct cylinders.
20Where applicable, refit the screening can
to the top of the distributor and reconnect the
earth strap. On fuel injection models,
reconnect the air inlet hose, ensuring that the
clips are correctly aligned (refer to illustration,
Section 15, Chapter 4, PartB).21Reconnect the battery negative lead.
22Check and if necessary adjust the ignition
timing.
Early “Economy” models
Removal
23Removal of the distributor fitted to these
models is a similar process to that described
above.
Refitting
24Turn the crankshaft to bring No 1 cylinder
to the firing point, with the 16º BTDC mark on
the crankshaft pulley aligned with the pointer
on the crankshaft front oil seal housing, as
described above.
25Fit the new distributor to the engine as
described above, then proceed as follows.
26Cut the original distributor wiring plug
from the wiring loom. Make the cut close to
the connector.
27Strip back 10 mm of insulation from each
of the wires on the wiring loom, and on the
adapter loom supplied with the new
distributor.
28Solder the adapter loom wires to the
corresponding identically coloured wires in
the main loom.
29Carefully insulate each individual soldered
joint using insulating tape, then apply tape to
cover the join between the looms.
30Fit a new distributor cap (and screening
can, where applicable), and connect the HT
leads.31Connect the adapter loom to the
distributor.
32Start the engine, and adjust the ignition
timing to the value given in the Specifications
at the beginning of this Chapter. Work as
described above whilst noting that the
vacuum pipe must be left connected.
Note: During production the ignition timing is
accurately set using a microwave process,
and sealant is applied to the distributor clamp
bolt. Because the electronic components
require no maintenance, checking the ignition
timing does not constitute part of the routine
maintenance schedule, and the procedure is
therefore only necessary after removal and
refitting of the distributor. A timing light will be
required for this procedure. For details of
ignition timing adjustment in order to operate
vehicles on unleaded petrol refer to the
appropriate Section of this Chapter.
All models except 2.0 litre DOHC
1Before checking the ignition timing, the
following conditions must be met:
a)The engine must be at normal operating
temperature
b)Where applicable, the vacuum pipe to the
distributor vacuum unit or electronic
module (as applicable) must be
disconnected from the vacuum unit or
electronic module and plugged
c)The idle speed must be below 900 rpm
(isolate “idle speed adjustment” wire if
necessary)
d)Any earthed “octane adjustment” wires
must be temporarily isolated
2Wipe clean the crankshaft pulley timing
marks and the pointer on the crankshaft front
oil seal housing. Note that two alternative
types of pulley may be fitted (see
illustration).The desired timing values are
given in the Specifications. If necessary, use
white paint or chalk to highlight the relevant
timing mark(s) (see illustration).
3Connect a stroboscope timing light to the
No 1 cylinder HT lead, following the
manufacturer’s instructions.
4With the engine idling at normal operating
temperature, point the timing light at the
marks on the crankshaft pulley, and check
that the appropriate timing mark appears
stationary in line with the timing cover pointer.
Take care not to get the timing light leads,
clothing etc tangled in the cooling fan blades
or other moving parts of the engine.
5If adjustment is necessary, stop the engine,
slacken the distributor clamp bolt, and turn
the distributor body slightly. Turn the
distributor body clockwise to retard the
ignition timing (move the timing closer to TDC)
and anti-clockwise to advance the timing.
16Ignition timing (OHC models)
- adjustment
Engine electrical systems 5•17
5
15.12 Removing distributor driveshaft O-
ring - Motorcraft distributor15.10 Unscrewing distributor clamp bolt -
Bosch distributor
16.2a Highlighted timing marks - SOHC
engine with cast crankshaft pulley

Note that the required distributor body
movement will be half of the required
crankshaft movement (ie an adjustment of 5º
in ignition timing will require the distributor
body to be turned 2º. Tighten the clamp bolt
and re-check the timing.
6On models with inductive discharge ignition
systems, the mechanical and vacuum
advance mechanisms can be checked as
follows. On all other models, proceed to
paragraph 10.
7With the engine idling, timing light
connected, and vacuum pipe disconnected as
described in the preceding paragraphs,
increase the engine speed to approximately
2000 rpm (if desired, connect a tachometer to
the engine in accordance with the
manufacturer”s instructions). Note the
approximate distance which the relevant pulley
mark moves out of alignment with the pointer.
8Reconnect the vacuum pipe to the
distributor or electronic module, as
applicable, and repeat the procedure given in
the previous paragraph, when for the same
increase in engine speed, the alignment
differential between the pulley mark and
pointer should be greater than previously
observed.
9If the pulley mark does not appear to move
during the first part of the check, a fault in the
distributor mechanical advance mechanism is
indicated. No increased movement of the
mark during the second part of the check
indicates a punctured diaphragm in the
distributor vacuum unit, or a leak in the
vacuum line.
10On completion of the adjustments and
checks, stop the engine and disconnect the
timing light. Where applicable, reconnect the
vacuum pipe, if not already done, and
reconnect any “octane adjustment” and “idle
speed adjustment” wires. Make a final check
to ensure that the distributor clamp bolt is
tight.
11Finally, the idle speed and mixture should
be checked and adjusted.2.0 litre DOHC carburettor model
12The ignition timing is controlled by the
ESC II module, and no adjustment is possible.
2.0 litre DOHC fuel injection
model
13The ignition timing is controlled by the
EEC IV module, and no adjustment is
possible.
Note: Refer to the Specifications Section at
the beginning of this Chapter for ignition
timing values for use with unleaded petrol.
1To run an engine on unleaded petrol,
certain criteria must be met, and it may be
helpful to first describe the various terms used
for the different types of petrol:
Normal leaded petrol (4-star, 97 RON):
Petrol which has a low amount of lead added
during manufacture (0.15 g/litre), in addition to
the natural lead found in crude oil.
Unleaded petrol (Premium, 95 RON):
Has no lead added during manufacture, but
still has the natural lead content of crude oil.
Lead free petrol: Contains no lead. It has
no lead added during manufacture, and the
natural lead content is refined out. This
type of petrol is not currently available for
general use in the UK and should not be
confused with unleaded petrol.
2To run an engine continuously on unleaded
petrol, suitable hardened valve seat inserts
must be fitted to the cylinder head.
3The OHC engines fitted to the Sierra/P100
range which have suitable valve seat inserts
fitted at manufacture can be identified by
letters stamped on the cylinder head next to
No 4 spark plug as follows:
1.6 litre enginesM, MM, N, or NN
1.6 litre enginesS or SS
2.0 litre enginesL, P, PP, R, or RR4All CVH engines have suitable valve seat
inserts fitted.
5Vehicles which have no identification letter
stamped on the cylinder head, and are not
fitted with suitable valve seat inserts, may still
be run on unleaded petrol (although
continuous use is not recommended),
provided that every fourth tank filling is of
normal leaded petrol, ie: three tanks of
unleaded petrol followed by one tank of
normal leaded petrol.
6When running an OHC engine on unleaded
petrol (Premium, 95 RON), the ignition timing
must be retarded as described in the
following sub-Sections. There is no
requirement for ignition timing adjustment
when running CVH engines on unleaded
petrol.
Inductive discharge ignition
system and ESC system
7On vehicles fitted with an inductive
discharge ignition system, or the ESC system,
the ignition timing should be retarded as
specified.
ESC II and EEC IV systems
8On vehicles fitted with the ESC II or EEC IV
systems, there is a facility for retarding the
ignition timing without physically disturbing
the distributor.
9Adjustment is made by earthing one or two
wires (“octane adjustment” wires) which
terminate in a wiring plug next to the ignition
coil. Ideally a service adjustment lead,
available from a Ford dealer should be used
(see illustration). One end of the lead plugs
into the “octane adjustment” wiring plug, and
the other end should be earthed by fixing to
one of the ignition coil securing screws.
10Cut and insulate the wires in the service
lead which are not to be earthed.
17Ignition timing -adjustmentfor
usewithunleadedpetrol
5•18Engine electrical systems
17.9 Service adjustment lead and plug -
ESC II and EEC IV systems
A Red, blue and yellow wires
B Plug
C Wire cutting point
16.2b Crankshaft pulley timing marks - SOHC engine
A Cast pulleyB Pressed steel pulley