1988 CITROEN CX check engine

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

CHECKING AND ADJUSTING
THE INJECTION SYSTEM
III. - ADJUSTING THE ROTO-DIESEL INJECTION PUMP CONTROLS
DPC type pump from engine M 25/648, Fig. I
DPA type pump from engine M 25/660, Fig. II
Checking the fast-idle control
Ensure that lever (7) is against its stop, by pushing
it in the direction of arrow (-).
If not, adjust tension of cab/e by means of cable end
clamp (6). Complete tightening of cable using sheath
tensioner (41.
Checking the fast-idle control
Make sure that the cable is slack.
If not, check the operation of the thermal sensor (101
located on the water outlet duct: the cable must ope-
rate over a range of 6 mm between its “ENGINE
COLD” and “ENGINE WARM” positions.
Adjusting the accelerator control
Engine stopped:
Fully depress the accelerator pedal.
Check that lever (I) is against stop (2).
If not, move pin (3) of accelerator cable.
Make sure that, at idle, lever (I) is against stop (5).
Adjusting the anti-stalling device
Engine running:
Insert a 1.5 mm thick shim (DPC pump, Fig. I)
2 mm thick shim (DPA pump, Fig. II)
between lever (I) and stop-screw (5) at “b”.
Place a 3 mm dia. rod through the hole in lever (7)
at “a” by pushing STOP lever (9) outwards. Set the engine speed to:
800 t 50 rpm (DPC pump)
800 f 25 rpm (DPA pump)
by turning stop screw (5).
Remove the 3 mm dia. rod and the shim
Adjust the idling speed to:
800 + 25 rpm
by turning stop screw (8).
Checking the engine deceleration:
Accelerate the engine to 3.000 rpm, then release the
accelerator lever sharply.
- if the deceleration is too fast (engine often stalling),
unscrew stop-screw (5) by 114 turn,
- if the deceleration is too slow (poor engine braking),
screw up stop-screw (51 by l/4 turn.
In both cases, check the idling speed and adjust if
necessary.
If the malfunction continues to exist, carry out the
adjustments again.
Check the efficiency of the mechanically operated
STOP control (9).
Note: The setting figures are identical if the vehicle
is equipped with air-conditioning and the adjustments
are to be effected with the air-conditioning off.

REMOVING/REFITTING D.P.A. AND D.P.C.
ROT0 DIESEL INJECTION PUMPS MA
146.1/l 5
REFITTING
Prepare
- the pump (see Op. @ MA 146.0/l/
Fit
- the pump with the mounting studs in the middle of
the slots,
- the pump fixing nuts but do not tighten home.
Assemble, Fig. I:
- the injection pump driving pinion t I); hand tighten
nut (2),
- the pump drive belt with the side opposed to the
tension roller being without slack (take care not to
rotate the pump).
Unscrew, Fig. I:
- tensioner nut (3); let the tensioner load the belt
without assistance.
Retighten, Fig. I:
- tensioner nut (3) to 2 mdaN,
- pinion nut (2) to 5 mdaN.
Carry out the pump timing:
Turn the pump towards the engine to find the point
of injection, (needle facing the “0” mark on the dial).
Screw up, Fig. II, to 2.4 mdaN,
- the pump fixing screws (4); when tightening, the dial
gauge needle should not move.
Check the pump timing (refer to @ MA 146.011)
Remove the tools
Refit:
- either the plug (tighten to 2 mdaN),
- or the inspection plate.
Seal the injection pump plug.
Refit:
- the belt upper protection cover,
- the wheelarch lining,
- the accelerator return spring,
- the injector set of feed pipes.
Tighten to 2.5 mdaN.
Recouple:
- the fast idle cable,
- the accelerator cable,
- the fuel pipe,
- the return pipe, D.P.C. pump, Fig. III.
Connect to the overfuelling circuit,
- the diesel fuel return pipe (61,
- the air pipe (5).
Put the fuel filter back into place.
Reconnect:
- the electric STOP solenoid,
- the negative cable to the battery.
Prime the fuel system using the manually operated
pump located on the filter.
Adjust the injection pump controls and idling speed
as explained in Op. @ MA 146.0/l.
8531

CHECKING THE PETROL SUPPLY
829.A5-J6T.A500
Pump AC DELCO TYPE: PB3
CHECKING THE PETROL PRESSURE WITH APPARATUS 4005-T:
- Position apparatus 4005-T.
- Disconnect the carburettor fuel return pipe; fit plug (2)
- Unscrew tap @ by one turn approx.
- Start the engine.
a) Check the petrol pressure at zero delivery:
- Fully screw up the tap; the pressure should not show a reading of more than 325 m.bar for the stabilised
pressure.
b) Check the tightness of the pump delivery valve:
- Stop the engine: there should not be a sudden drop in pressure.
c) Check the tightness of the carburettor needle valve:
- Unscrew tap @ ; start the engine, leave it running for a few minutes.
- Stop the engine: there should not be a sudden drop in pressure.
- Remove apparatus 4005-T and fit the fuel supply pipe and the fuel return pipe to the carburettor
(after plug (2) has been removed).
CHECKING THE PUMP FOR LEAKS:
Close the pump delivery tube. Blow compressed air under 800 m.bar pressure into the suction pipe. Immerse the
pump in a container filled with clean White Spirit: no leak should be detected.

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