ignition CITROEN CX 1988 Service Manual

USE OF THE MANUAL
PRESENTATION
The Repair Manual comes in a binder with a “Mu/to” type
mechanism to facilitate the filing of additive sheets
or the removal of a part for operation in the workshop.
The MECHANICAL COMPONENTS, PART 1 VOLUME (8531) covers operations on the MECHANlCAL
COMPONENTS and the BODYWORK which may be carried out by a general workshop.
It is divided into 15 chapters separated by vinyl tab inserts numbered @ to @
General
Engine
Fuel system-Carburettor
Ignition system
Clutch
Gearbox-Drive shafts
Source and reserve of pressure
Front axle Rear axle
Suspension - wheels - tyres
Steering
Braking system
Electrical equipment and radio
Heater, ventilation and air-conditioning
Bodywork
COMPOSITION OF A CHAPTER
Each chapter includes:
-
the list of operations in it,
-
the operations in numerical order.
OPERATIONS
The operation references are made up as follow: MA 100 - 00 II a
-
a) z T-r TiiTz
a) vehicle code letters: MA
b) three figure number identifying the assembly or the assembly part
c) figure indicating the type of operation:
-
the figures 000 indicate the vehicle specification
- the figures 00 indicate the assembly specification
- the figures 0 indicate checks and adjustments
- the figures 1 indicate removals and refittings
- the figures 2 indicate dismantling and re-assembly
-
the figures 3 indicate reconditioning
d) figure /I,... /2.../... standing for a variant,
e) letter: a, b, standing for an evolution
rious operations are presented:
1’ either through photos, drawings and texts,
hrough photos, drawings and symbols.
‘!%.OSSARY has been placed at the beginning of each volume for this purpose.
e glossary (the one in the Mechanical Components volume is different from the one in
caning for each symbol has been translated into nine languages.
kts in a removable set of “plastic” sheets bound with one manceuvrable me
ion of one or several pages (and obtain photocopies from them, for instance). the Bodywork volur nel,
‘tal r ing to facilitate the
85 31

PROTECTION OF THE ELECTRICAL COMPONENTS
PRECAUTIONS TO BE TAKEN WHEN CARRYING OUT AN OPERATION ON THE VEHICLE
It is essential to avoid actrons which may damage the electrical or the electronic equipment or create a short circuit
(wrth subsequent risk of fire or accident).
Battery:
a) First disconnect cable clamp from the battery negative terminal, earthed, then from the positive post.
b 1 Before tightening the negative clamp to the battery (the negative lead should be connected last), ensure that there
is no short circuit (bright sparks or arcs).
Small sparks may occur due to the interior lamp (door open), door locking device, clock or components having
remained in operation.
c 1 Make sure that the terminals are properly connected. Clamps and terminals should be clean and correctly tightened.
d ) When recharging the battery, disconnect the two clamps first.
e) Do not reverse the negative and positive clamps on the battery. (This could destroy the alternator diodes).
Fuses:
a 1 Fit the correct type of fuses: use the fuses specified for the protected devices
b 1 Take the added accessories and the functions into consideration.
Charging circuit:
,a 1 Do not run the alternator unless it is connected to the battery. Do not disconnect the battery when the alternator
is rotating.
b 1 Ensure that the regulator is correctly earthed.
c ) Do not interchange the leads connected to the regulator, (charge detection warning lamp and excitation are specific).
d ) Do not connect a suppressor capacitor to the regulator without taking precautions or following proper
instructions.
e 1 Do not use an electric welding equipment on the vehicle without having first disconnected the alternator, the regula-
tor and the battery (insulate the two terminals).
f 1 Do not R check )) the operation of an alternator by short circuiting the positive and ground terminals, which may
destroy the diodes.
Starting the engine:
Do not use a booster or a 24-volt battery. Only use a correctly charged 12-volt battery (a higher capacity battery may
be utilised). Otherwise, risk of deterioration of the ignition module or any other electronic control units. If the starter
is needed for starting the engine, without running it, it is necessary to disconnect datum and flywheel sensors on the
All Electronic Ignition, or the primary lead of the coil on any other type of ignition.
Ignition:
a 1 Do not connect a suppressor capacitor to the negative terminal of the coil.
b 1 Do not operate the module if its radiator is not connected to the earth.
c 1 Fit the radio suppressor capacitors recommended by the factory.
d 1 Never operate the ignition system while the HT circuit is open. Connect the HT leads to earth
e) Only use rev. counter having a HT sensor, (never puncture HT leads).
0.1. bulb:
a) Never replace a 01. bulb with the headlamp switched on. If the headlamps have been in use, allow them to cool down.
b) Do not touch a 0.1. bulb with bare fingers. Any fingerprints must be cleaned with soapy water and the bulb dried
with a dry lint-free cloth.
Checks :
a) Preferably use a high resistance (> 10 k Q VI voltmeter or a battery-operated ohm-meter
b) Take care not to use instruments taking their power from the mains.
Electronic components:
a) Avoid overvoltages due to a badly insulated charger, electric arcing or connections to the coil.
The units such as regulator, ignition module, tachometer, windscreen wiper timer, flasher unit, clock, radio, oil gauge
unit, door lock control unit, etc. comprising electronic components may be deteriorated.
b) The electronic components should not be placed or operated under a temperature exceeding 80°C.
c) Always switch off instruments or electronic control units before connecting or disconnecting them.
‘

GENERAL FEATURES OF THE CARBURATION
FITTING. Fig. I:
5. FIN the tamper-proof protective plug (a):
- load gun A,
- screw tool E onto gun A,
- position plug (a) in its housing on the carburettor (make sure it is fitted the right way round Fig. 111,
- actuate the gun until the plug is properly located.
EXHAUST EMISSION CONTROL
In order to comply with current regulations, the checking and adjustment of the exhaust emission from vehicles
with a petrol engine must, without fail, be performed after the following operations:
I. ENGINE REPLACEMENT.
II. CARBURETTOR REPLACEMENT.
Ill. WORK ON THE CARBURETTOR.
Replacement of parts of the carburettor.
Carburettor adjustment.
Work on the carburettor controls.
IV. WORK ON THE INLET MANIFOLD.
Replacement or removal of:
- the inlet manifold,
- the air filter,
- crankcase gas recirculation system
V. WORK ON THE ENGINE.
Rocker adjustment.
Replacement or removal of:
- the cylinder head,
- the camshaft,
- the rockers,
- the valves,
- the liners and pistons.
VI. WORK ON THE IGNITION.
Replacement or reconditioning of the distributor (wholly or partially)
Adjustment or replacement of the sparking plugs.
Adjustment of the ignition timing.
VII. WORK ON EXHAUST SYSTEM.
Replacement or removal of:
- the exhaust manifold,
- the silencer or any part of the exhaust.
VIII. WORK ON THE EMISSION CONTROL SYSTEM.
When the vehicle is fitted with a specific equipment (e.g. on vehicles of SWEDEN, AUSTRALlA or JAPAN type)

CHECKING AND ADJUSTING
THE INJECTION SYSTEM
II. - INSPECTION AND TIMING OF THE “ROT0-DIESEL” INJECTION PUMP
Raise the LH side of the vehicle and support it on
stands.
Disconnect the battery negative lead.
Engage the 5th gear. Rotate the engine by turning the
wheel.
Set the No. 1 cylinder to the initial timing point,
Fig.1.
(look into the oil filter orifice).
- place cylinder No. 1 valves in the rocking position;
turn the crankshaft by one turn in the normal direc-
tion of engine rotation.
- align marks on the flywheel and on the crankcase
(++I.
- turn the crankshaft back through a quarter of a turn.
Remove either the plug (with a 32 mm ring spanner)
or the inspection plate depending on the type of the
pump.
Refit, Fig II or Ill, according to pump:
- the feeler,
- the support for the dial-gauge.
- the dial-gauge equipped with its right-angled lever.
Finding the pump internal timing point:
- turn the crankshaft in the direction of rotation until
the large pointer on the dial indicator starts moving
in the opposite direction.
- set “0” mark on the dial-gauge in line with the large
pointer.
Checking the injection pump timing:
- rotate the crankshaft by a quarter turn in the oppo-
site direction to its direction of rotation.
- turn back in the normal direction of rotation until the
“0” mark on the dial-gauge has been reached.
- in that position, marks (-1 and (c) should be in line,
Fig. I.
If not, re-check the timing. Timing the injection pump:
- set the engine to the initial trming point, Fig. I.
- turn the crankshaft by 114 turn in the opposite direc-
tion to normal direction of ro’tatron, then turn back
in the direction of rotation to bring marks t-+) and
+-I opposite.
Adjusting the pump timing, Fig. Ill:
Slacken off the injector pipe connections and the 4
attachment points.
Bring the pump to the injection point with the feeler
at the base of V-shaped groove (timing point).
Set the “0” mark on the dial opposite the needle on
the dial-gauge. Orientate the pump casing towards the
engine.
Slowly turn back to the injection point (needle facing
the “0” mark on the dial), by moving the pump
casing away from the engine (in the opposite direc-
tion to engine rotation).
Tighten the pump fixing nuts to 2.4 mdaN. During
this operation, the needle should not move.
Check the pump timing
Remove the timing tools.
Refit the plug, (tighten to 2 mdaN), or the inspec-
tion plate.
Seal the injection pump plug.
Tighten the injector pipe connections to 2 mdaN.
Reconnect the battery negative cable
Switch on the ignition (electrical STOP solenoid exci-
tation) and prime the fuel circuit using the manual
pump (5) located on the filter.
Fully depress the accelerator pedal to facilitate the
engine bleeding and start.
Note: the initial timing point corresponds to:
3.24 -L- 0.05 mm BTDC: M 25/648
4.32 + 0.05 mm BTDC: M 25/660 DPA pump
4.71 f 0.05 mm BTDC: M 25/660 DPC pump
8531

ITION SYSTEM
GENERAL /NFORMATlON
ON THE TRANSISTORISED IGNITION
8531

GENERAL FEATURES
OF THE TRANSISTORISED IGNITION SYSTEM
TRANSISTORISED IGNITION
PRINCIPLE OF OPERATION
The plug spark is triggered by distributor (1) which comprises a coil located inside the field of a magnetic circuit
permanent magnet. The magnetic circuit has four fixed branches and four movable branches driven by the distribu-
tor shaft.
When the movable branches, in their rotation, come opposite the fixed ones, a variation of the magnetic field is
brought and current is induced into the sensor winding.
This current, in turn, triggers electronic module (2)
which builds up the current in ignition coil (3) primary winding
and then cuts it off, thus creating a high tension current in the coil secondary winding and triggering a spark from
the plug selected by the distributor rotor arm. IGNITION DISTRIBUTOR (I!
The advance curves are specific for each engine type
N: Distributor rpm
D = Vacuum Dl, in m.bars A:
Distributor degrees 02, in mm.hg
Pick-up coil resistance: 1100 Q sr 10% (990 to 1210 02)
Setting the distributor static timing on the engine is impossible owing to design.
A revolution of the distributor is required to create a variation of the magnetic field which will send a signal to the
module. Consequently, when fitting a distributor, place it in mid-slot; start the engine and adjust the distributor
by means of a timing light or a diagnosis console.
The duration and amplitude of the signal depend on the speed, therefore the DWELL ratio
is not significant.
The air gap between the branches is non-adjustable and it cannot be measured ELECTRONIC MODULE (2)
Intended to operate with the magnetically-triggered distributor.
Do not carry out a check with an ohmmeter since the results would not be significant.
Do not operate the module without cooling (aluminium plate heat sink and heat conductor grease).
The operation of the ignition system is possible with the engine stopped: - connect an earthed sparking plug to
the coil HT lead; short ” + 12 volts” pulses on module red lead (path 5) (with all leads connected, cap lifted) will
generate a spark from the plug: simulation of a signal from the distributor pick up).
Do not operate the module and coil without a plug and HT lead, (It could result in the module being destroyed). IGNITION COIL (3)
The coil must not be kept alive under 12 volts without its module (overheating).
The coil current flow is generated by the module which then reduces it, prior to cutting it off when the engine
ignition timing occurs.
Only use a rev. counter with a UT induction clip.

CHECKlNG THE TRANSISTORISED IGNITION
ELECTRO-MAGNETICALLY TRIGGERED TRANSISTORISED IGNITION
PRELIMINARY CHECKS:
Inspect:
- the connection of the different leads (in particular to coil: a bad connection can cause a high voltage drop preven-
ting the current from passing into the coil primary winding (I 5 A approx),
- condition of the leads : (circuits broken, short-circuits across screening, etc.),
- condition of the sparking plugs (deposits, cracks due to overtightening),
- condition of the distributor cap (wear, cracks) and the rotor arm (loose).
Disconnect the interference suppression capacitor and the diagnosis harness, from the circuit.
Carry out a ((spark test)) with the starter motor and one plug earthed.
IMPORTANT: The module may be destroyed if one of the secondary wires is too far from the earth. CHECKING THE COIL (3) (ignition module and supply to coil disconnected):
MEASUREMENT OF Ohmmeter placed between channels No. Reading (in 0)
Primary winding resistance 1 and 4 DUCELLIER 0.76 to 0.84
BOSCH 0.74 to 0.90
Secondary coil resistance 1 4 and HT coil contact DUCELLIER 5700 to 6300
or
BOSCH 7425 to 9075
Insulation 1 or 4 and earth 00
Checking the coil power supply using a lamp or a voltmeter:
- Switch on the ignition: there should be a 12V current between the “BAT” terminal of the coil and the earth
- Switch off ignition. CHECKING THE IGNITION MODULE (2):
The module is designed to function with the ignition distributor and the coil.
- Do not operate the module without cooling (aluminium plate heat sink) or ventilation
- Do not check the module with an ohmmeter since the results will be non-significant.
Checking the module power supply using a lamp or a voltmeter:
- Disconnect the module connector
- Switch on the ignition: there should be a 12 V current between the channel 4 of the connector and the earth.
- Switch off ignition.
The low voltage ignition circuit being connected (in working order), disconnect the coil - distributor HT lead on
the distributor side and connect it up to an earthed plug: by sending short pulses ( + 12 VI to channel 5 (red wire)
from the module, sparks should occur at the plug (simulation of distributor spark current). CHECKING THE IGNITION DISTRIBUTOR (1):
Test the impulse generator with the module connector disconnected. MEASUREMENT OF:
Resistance
Earth
Insulation Ohmmeter placed between channels No. 5 and 6
2 and engine earth
5 and 2 then 5 and 3 Readings (in Q) 950 to 1250 approx.
0
m
,

CHECKING THE TRANSISTORISED IGNITION MA
210.0/l 7 CHECKING THE DISTRIBUTOR ON TEST BENCH, Fig. I
To check the magnetic distributor on the bench, a transistorised module in good condition is essential. Use the
vehicle module and leads if the bench is not equipped. The ignition coil is not required.
CHECKING THE CENTRIFUGAL SPARK ADVANCE
Fit the distributor onto the bench:
Connect module (3) and distributor (I 1 to the harness (2)
Connect wiring harness plugs (2) to test bench:
To check the distributor: Fig. II and Ill.
Compare the distributor centrifugal spark advance curve with the theoretical curve:
- If the curve plotted does not correspond to the theoretical curve, modify the spring tension by bending the spring
hooking point support plate.
In order to do this, remove the cap and alter the spring tension by bending the attaching bracket, Fig. Ill and IV.
(D
: release the spring, T : tighten the spring) , Curve measured
I
II
Ill
IV Spring concerned
5
5
4 released
4 not in use Bending direction
T
D
T
D
CHECKING THE VACUUM SPARK ADVANCE
Compare the distributor vacuum spark advance curve with the theoretical curve
NOTE: The vacuum spark advance device is not adjustable: If the curve measured is out of tolerance, change the
capsule. ADJUSTMENT ON THE VEHICLE
Distributor timing:
- Fit the distributor, positioning it approximately midway between the slotted holes.
- Start the engine.
- The vacuum capsule being disconnected, use a strobe lamp to set the distributor timing to:
Advance (degrees
before TDC)
Engine rpm cx20 cx22
IO0 lo0
750
I 800
- Reconnect the vacuum capsule.
8531

CHECKING THE INTEGRATED ELECTRONlC
IGNITION (I.E.I.)
TEST PROCEDURE USING CONVENTIONAL EQUIPMENT
on the CX 2500 vehicle with M 25/659 type engine
l Checking the voltage in the secondary winding of each coil
0 Operating procedure: Disconnect one sparking plug and bring the end of the released wire 1 cm approx
from the crankcase. (Repeat the operation for each set of cylinders).
l Operate the starter motor:
if a spark occurs The incident is not to be attributed to the I.E.I.
Check the injection system, the valve timing, the rockers etc.
- examine the engine sparking plugs.
- inspect the circuit between the I.E.I. control unit white terminal 1 and the fuel
injection control unit terminal 15 for continuity: read 0 0, the connectors from
the control units being disconnected.
if no spark occurs The incident is due to the ignition system--ccarry on to next tests.
l Working on the primary winding of each coil
Operating procedure: Connect a 12V warning lamp of the Wedge base type between the negative and
0 the positive terminals of the coil (i.e. between terminals 1 and 3, connectors con-
netted to coil).
l Operate the starter motor:
if no regular breaks occur incident in the coil primary winding
or
incident in the E.C.U. control circuit.
if regular breaks occur incident in the secondary winding
The following checks are to be carried out with I.E.I. and fuel injection control units connectors disconnected.
l Checking the coil primary windings:
Operating procedure: Measure the resistance between terminals 1 and 9 of the I.E.I. control unit black
0 connector: Read = 2.5 0.
Warning: the ignition should be switched off.
If the reading is incorrect, investigate for a failure in this circuit.
l Checking the E.C.U. pick up sensors:
co Operating procedure: Measure the resistance between terminals 5 and 12 then 6 and 13 of the I.E.I.
control unit black connector: Read = 50 a.
l Checking the feed for the E.C.U. and earth connection, with ignition switched on
Operating procedure: Measure the voltage between terminals IO (white connector) and 2 (black con-
nector) of the I.E.I. computer: Read the battery voltage.
The same check should be carried out between terminals 2 (earth) and 11 of the black connector:
ignition switched on, starter motor operated, read the voltage.
69 l Check that the distance between the datum sensor and the flywheel ring is 1 mm + 0.5.
0 l Incident on the ignition circuit secondary winding: make sure that the resistance of each coil
winding is: 350014000 a.
8531

CHECKING THE I.E.I.
TEST PROCEDURE USING CONVENTIONAL EQUIPMENT
on the CX 2500 Turbo vehicle with M 25/662 type engine
0 Checking the voltage in the secondary winding of each coil
0 Operating procedure: Disconnect one sparking plug and bring the end of the released wire 1 cm approx
from the crankcase. (Repeat the operation for each set of cylinders).
0 Operate the starter motor,
if a spark occurs
if no spark occurs The incident is not to be attributed to the I.E.I.
Check the injection system, the valve timing, the rockers etc.
- examine the engine sparking plugs.
- inspect the circuit between the I.E.I. control unit white terminal 1 and the fuel
injection control unit terminal 15 for continuity: read 0 Q, the connectors from
the control units being disconnected.
The incident is due to the ignition system-carry on to next tests.
l Working on the primary winding of each coil
Operating procedure: Connect a 12V warning lamp of the Wedge base type between the negative and
the positive terminals of the coil (i.e. between terminals 1 and 3, connectors con-
netted to coil).
l Operate the starter motor,
if no regular breaks occur incident in the coil primary winding
or
incident in the E.C.U. control circuit.
if regular breaks occur incident in the secondary winding
The following checks are to be carried out with I.E.I. and fuel injection control units connectors disconnected.
0 Checking the coil primary windings:
Operating procedure: Measure the resistance between terminals 1 and 9 of the I.E.I. control unit black
0 connector: Read = 2.5 Q.
Warning: the ignition should be switched off.
If the reading is incorrect, investigate for a failure in this circuit.
l Checking the E.C.U. pick up sensors:
OI Operating procedure: Measure the resistance between terminals 5 and 12 then 6 and 13 of the I.E.I.
4
control unit black connector: Read 2: 5OQ
0 Checking the feed for the E.C.U. and earth connection, with ignition switched on.
d 5 Operating procedure: Measure the voltage between terminals 10 (white connector) and 2 (black con-
nectar) of the I.E.I. computer: Read the battery voltage.
The same check should be carried out between terminals 2 (earth) and 11 of the black connector:
ignition switched on, starter motor operated, read the voltage.
@ 0 Check that the distance between the datum sensor and the flywheel ring is 1 mm + 0.5.
0 * Incident on the ignition circuit secondary winding: make sure that the resistance of each coil
winding is: 350014OOOQ.