1981 Citroen CX check engine

Downloaded from www.Manualslib.com manuals search engine 2
OPERATION No MA. 142.0 SD : (./ )I c ,,,s m,d nd;,,s/is~~ /A? Ni/li-/Joll,lli,,ill I \/i’V, b’
/ Sll l:l~/sl1 lI.\KKI:I v1:/1/c l.JT I,
CHECKING THE IDLING SPEED AND THE CO READING I (.. JXO J
On cr vehicle fitted with the following :
-distributor : DUCELLIER 4510 B
Dwell ratio 61 7: + 3 ‘Y
Dwell angle 550 + 2”
Static advance 6”
Strobe timinq
6” at 850 rpm
Centrifuqal cuwe IA 2
- carburettor : WEBER 34 DMTR 30/200 Identification mark W 63-00
spark plugs: AC 42 FS
- engine, with the following rocker clearances : Inlet = 0.15 mm, Exhaust = 0.20 mm
Checking and adjusting the CO is carried out in the following conditions
1. Disconnect from the air-supply valve ( 3) the pipe from the valve to the exhaust manifold
2. Bring the engine oil up to a temperature of 85 ? 5’ C
3. Wait for the cooling ion ( 01
ims J to cut in.
4. Adjust screw ( 3) for opening of first choke butterfly in order to obtain on idling speed of 850 to 900 rpm
5. Slowly adjust the mixture screw (2) so (IS to obtain a CO reading of 2 to 3 “L for a temperature of 15” to 30 C
6. Adjust the mixture screw (2 ) lost
7. Connect to the air-supply valve (3 ) the pipe from the valve to the exhaust manifold.

Downloaded from www.Manualslib.com manuals search engine CHECKING THE SAFETY DEVICE FOR THE CHOKE
f (.X 2000 j :
1. Electrical components :
Disconnect the u blur )) lead feeding the thermal
switch (1) located on the water outlet duct on
the cylinder head.
Switch on the ignition.
Earth the lead from thermal switch ( 1) the relay ( 2 )
for the << WEBER 1) electro-valve ( 3) must operate.
Leave the thermal switch disconnected with the
lead insulated from earth.
Pull the
choke knob. electro-valve (3) is supplied
by relay (2 ) and is closed by earthing via the choke
control.
2. Pneumatic components :
Disconnect from the air-supply valve ( 5) the
pipe (4) from the valve to the exhaust manifold.
Plug the pipe in order to avoid the exhaust pressure
deteriorating the end of the tube and the valve
Use the starter to rotate the engine.
In this position. the air pump (6 j must
not supply
air through the previously disconnected opening in
the air supply valve ( 5)
CHECKING THE AIR INJECTION
Push back the choke
In this position. the air-pump (6 ) must supply air
through the previously disconnected opening in the
air-supply valve ( 5 1.
Accelerate the engine, and suddenly decelerate
The injection of air throuqh the opening must stop
for a short while.
Run the engine until the cooling fan ( or fans ) cut
in.
Pull the choke out : the air flow through the opening
in the air supply valve ( 5) must cease.
Push the choke in : the air flow must resume.
Connect to the air-supply valve ( 5) the pipe ( 4 )
from the valve to the exhaust manifold.

Downloaded from www.Manualslib.com manuals search engine CHECKING THE DEVICE FOR OPENING THE
BUTTERFLY
1. Electrical components :
With the engine at idling spu~d. disconnect one
of the leads to the C< PIERBURG ,) electro-valve (1).
the engine speed must increase.
If not. using a test lamp, check the following
that.
under deceleration and for any engine
speed
Nd > 1800 ? 100 rpm the /C PIERBURG >l
electro-valve (1 ) is not energized.
- that.
under acceleration and for any engine
speed from idling speed to the speed
Nc = Nd + 50 to 250 rpm. the C< PIERBURG ,,
electro-valve is energized.
If in this case the electro-valve is not energized.
ensure ( using a test lamp ) that the winding in
relay ( 2) is not enerqized for an engine speed
below ”
Nd ” ( under deceleration ) or an engine
speed below ”
NC ” ( under acceleration ).
Accelerate the engine up to engine speed ”
NC n :
- the winding in relay (2 ) must be enerqized.
If not. replace the electronic unit (3) after
having checked the connections.
2. Pneumatic components :
Ensure that the vacuum reaches capsule ( 4 1 ( device
for opening butterfly ) when the engine speed is
equal or above ”
NC “.
Make sure the vacuum exists at the carburettor
outlet. If it does. and yet does not reach cap-
sule (4) ( device for opening butterfly 1. check
the circuit along all its length. plugging it first
level with the 3-way union. on the air-supply
valve side.

Downloaded from www.Manualslib.com manuals search engine OPERATION No MA. 142-O SD : (i ‘CC ,ii:: md nr/;,,sfinji //I<, “~,ti.pOlllLliol, .S,Sl~l,, k’
c s 11’1:/~12/1 ,\lAHKli’/ “,iH,(.,.li.S , Op. MA. 142-O SD 5
ADJUSTING THE IDLING SPEED AND THE CO READING ( (.. ‘01~0 I
- IMPORTANT : II i nhsr,l,,/<~l, irirhi<&,, ,o rhnri~q~, /he sv//ing o, .Y,<,,I-r< lo,, , I , ,o, //a~ ~i.l <’ h,,,,<~r-,,,
2 I, hirh hns /,<,,‘I, “ : 0
m n (I vehicle fitted with the following :
m
-.
“, - distributor : DUCELLIER 4510 B
6
Dwell ratio 61 ‘:: ? 3 ‘,
x
2 Dwell angle
557 i 2=
Static advance 6
i
Strobe liming 6. at 850 rpm
;
F Centrifugal curve LA 2
a
a - carburettor : WEBER 34 DMTR 29/200 Identification mark W 61-00
5
“2 - spark plugs : AC 42 FS ( g.ap : 0.7 mm )
- engine with the following rocker cleoronces : Inlet 0.15 mm, Exhaust : 0.20 mm
Checking or adjusting the CO reading is carried out in the following conditions
1. Disconnect from the air-supply valve the pipe from the valve to the exhaust mariifold.
2. Bring the engine ail up to a temperature of 85” ? 5” C.
3. Wait.until the cooling fan f or fnvs 1 cut in.
4. Adjust screw ( 3) for the first choke butterfly in order to obtain on idling speed of 850 to 900 rpm
5. Slowly adjust the mixture screw (2 ) so as to obtain a CO reading of 2 to 3 “A for a temperature of 15 to 30” C
6. Adjust the mixture screw (2 1 last.
7. Adiust the throttle butterfly opening :
Disconnect one of the leads from the S( PIERBURG n electro-valve
Adjust screw (4) to obtain on engine speed of 1450 + 50 rpm
Connect the S< PIERBURG n electro-valve
8. Connect to the air-supply valve, the pipe from the valve to the exhaust manifold.

Downloaded from www.Manualslib.com manuals search engine Op. MA.IE. 144-O 1 I - PRECAUTIONS TO BE TAKEN WHEN WORKII;(G ON A VEHICLE FITTED WITH THE (t L-JETRONIC n
SYSTEM.
1.
Do not run the engine if the battery leads are improperly secured
2. Do not use a quick-start charging trolley for starting the engine
3. Never disconnect the battery with the engine running
4. When charging the battery, disconnect the leads
5. Before checking the injection system, check the ignition : (advance, advance curve, proper grade of plugs 1
6. Remove the E C U before putting the vehicle through a paint-stoving oven
7. Check the conditions of the various connections
8. Never disconnect the E,C U. while the ignition is on
9. When checking compression, disconnect the positive terminal of the coil (in order to stop the injection signal). 10.
When carrying out a check requiring an ohmmeter, use exclusively a battery-powered ohmmeter. II. FAULT-FINDING.
1. THE ENGINE DOES NOT START, OR IS DIFFICULT TO START . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 2
2. THE ENGINE STARTS, THEN STOPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. 3
3. UNSTABLE OR INCORRECT IDLING SPEED, EXCESSIVE FUEL CONSUMPTION ........................ P:5
-4. ENGINE MISFIRES AT .ALL SPEEDS ........................................................................................................
P. 7
5. LACK OF POWER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ................ P. 9

Downloaded from www.Manualslib.com manuals search engine Ill. CHECKING AND ADJUSTING
1
. Energizing the system ..................................................................................................................
2. ,Fuel pump feed ( on operating the starter ) .............................................................................
3. Fuel pump feed ( with engine running ) ...................................................................................
4. Supplementary air control ...........................................................................................................
5. Air-flow sensor ............................................................................................................................
6. Resistors and injectors ................................................................................................... . ........
7. Water temperature sensor ............................................................................................................ .
Dingram 7
8. Air temperature sensor ...............................................................................................................
9. Cold-start injector, and thermal switch ...................................................................................
10. Switch on throttle butterfly spindle ( idling speed function ) ............................................ 11
Switch on throttle butterfly spindle ( maximum power function ) ...................................... 12.
E.C.U: ......................................................................... ..~ ............................................................... . . Diagram 1 I ANNEXE : A
: Checking the ignition .................................................................................. Page 25 B
: Checking the air circuit ................................................................................ Page 26
C : Checking the fuel system and the fuel pressure ........................................... Page 27 D
: Adjusting the idling speed and the exhaust emission .............................. Page 28 NOTE
: On the wiring harness for the injectors, the numbers of the terminals on the E.C.U. terminal board are
visible on the rear section. after having withdrawn the casing secured by the end screw.

Downloaded from www.Manualslib.com manuals search engine 1. Energizing the system : ( DIAGRAM 1 )
_ Disconnect the E.C U
- Switch the ignition on
Using a voltmeter. ensure that each point in
dingrm 1 is effectively energised. after having tested the
earthing. If not, switch off the ignition. and test the circuit using a battery operated ohmmeter. With the
voltmeter connected between terminals ( 1 ) and ( 5) of the E. C.U., operate the starter the voltmeter must
register the ignition impulses If it does not. check the ignition
( ANNEXE A ).
2. Fuel pump feed ( on operating the starter ) ( DIAGRAM 2 )
- Disconnect the E C.U.
- Switch on the ignition
- On operating the starter. the fuel pump (
secureri rrt/rler the I c~hiclc’. uoor IIJO K. ti. ronr (, l~eol I must be
heard to operate by someone standing close by
If not switch off the ignition, and test the circuit using a battery operated ohmmeter.
The resistance between terminal (( 88 d H of the relay assembly ( c~r~tler 111~
L,H. honr/llor)~p ) and earth
must be 1 Q approx-
Make sure the petrol pump is properly earthed.

Downloaded from www.Manualslib.com manuals search engine Op. MA.IE 444-O 15
3. Fuel pump feed ( with engine running ) : ( DIAGRAM 3 )
- Disconnect the E.C.U.
- Disconnect from the air-flow sensor the air hose to the butterfly housing
- Switch on the ignition:
- Actuate the air-flow sensor flap by hand’ when the petrol pump contact closes the pump should be heard
working.
If not, test the circuit using a
battery operated ohmmeter, without forgetting to test between terminal G 36 ))
on the air-flow sensor and terminal H 20 .)) on the E.C.U. for continuity ( The 2nd terminal is not connected
to the E.C.U. ).
- The resistance between terminals (( 86 b H and G 85 )) on the relay box f //j/nor thc~ I~./I. h<~ntllnr~tp ) must be
between 52 and 78 12.
P 4. Supplementary air control ( DIAGRAM 4 )
4
c
5
6
- Disconnect the E.C.U.
-E
? - Check that the supplementary air control is properly connected ( arrow on the casing )~
In
If it is fitted the wrong way round. the port may be blocked.
- The resistance between terminals (( 34 1, and (( 48 )) on the- supplementary air control must be 50 Q approx-
- Visual checking the port on the supplementary air control must be open when the engine is cold, and closed
when the engine temperature is above 60” C
- With the engine cold. if the air pipe to the supplementary air control is flattened the engine rpm must decrease.
With the engine warm, if the air pipe is disconnected, the engine must accelerate.