1988 CITROEN CX Service Manual

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.
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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.

CHECKING THE IGNITION SYSTEM
USING CHECKING EQUIPMENT OUT 106 029T
The instrument can be utilised on CX 2400 I.E. with naturally aspirated engine and CX 2500 I.E. TURBO. Howe-
ver, on CX 2400 I.E. having an integrated electronic ignition system with a single connector E.C.U., it is neces-
sary to proceed as follows:
- connect the I.E.I. control unit to the black connector of OUT 105 029.T
- set the switch of the apparatus to the “1 connector” position
- I.E.I. with 1 or 2 sensors can be checked with this device.
a) Testing the ignition coil primary winding:
- The warning lamps, one at each coil, blink rythmically with the impulses transmitted to their primary win-
ding. Steady blinks indicate that there is enough current to generate a spark in the secondary winding.
- The switch situated under the warning lamps makes it possible for the primary windings of both coils to
be insulated, by pushing, in the “out of circuit“ position, any interference coming from the HT circuit when
the frequency of illumination for sensor warning lamps is checked.
- If the warning lamps blinking is correct, the failure may be caused by:
- the ignition information to the fuel injection control unit, (paragraph c),
- the secondary winding (coil wires, coils),
- any other item required for a correct operation of the engine such as injection, valve gear, rockers etc.) -
If the warning lamps blinking is not correct, examine the control unit warning lamps, (paragraph b),
b) Testing the sensors: -
The warning lamp connected with the “datum” sensor blinks rythmically with the impulses transmitted by
the peg, i.e. one blink per engine revolution, (2 sensors fitted).
- The warning lamp connected with the “flywheel pick up” sensor, blinks rythmically with the impulses sent ’
by the flywheel teeth.
The frequency of the flashes is such as they can hardly be seen.
Apparently, the lamp stays on, (1 or 2 sensors fitted).
On the CX 2400 I.E. and 2500 I.E. with normally aspirated engine, the vacuum pressure warning lamp lights
up momentarily after a sharp acceleration: this warning lamp is no longer usable on the CX 2500 I.E. with
turbocharger.
c) Tests related with the I.E.I. control unit:
E.C.U. functions: -
The rev. counter warning lamp blinks rythmically with the impulses transmitted to the rev. counter.
- The injection warning lamp blinks rythmically with the impulses sent to the fuel injection control unit
+k 8531