1981 Citroen CX ECU

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 after having withdrawn the casing secured by the end screw.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 OPERATION No MA. 210-O : (.h(~~-ki/lg n~lc/ c~tlj~~s/irtg the igrlitiorl Op. MA. 210-O 3
1. Checking the condition of the contacts :
Check the voltage drop across the contacts ( contacts closed ) under a voltage of 12 volts. using a test-bench.
The voltage drop should be 0.2 volts max.
I
2. Checking the centrifugal advance curve :
a) Note the advance in stages for steadily increasing engine speeds from 0 to 3000 rpm. and for steadily
decreasing engine speeds from 3000 rpm to 0, t~/~kjj/$ SII~L’
the irirwasc, or d~,rrc~as~’ is c-o~~ti~ootl.5.
These points must fall within the shaded area of the curve.
b) To a certain extent. it is possible to correct the advance curve, by altering the tension of the springs for
the centrifugal weights To obtain this condition, slightly bend (
iv t/1(, np1)ro/)riotc, ciirectioll J the securing
brackets for the springs, or replace them.
IY NOTE : If luminous spots are produced outside the four normal positions at speeds under 3000 rpm. make
5 sure the contact points are clean and if necessary make sure the test-bench battery is fully charged. before
U replacing the contact-breaker unit. the spring of which may have weakened.
7
co
m
r 3. Checking the spark regularity :
2
Whatever the speed of rotation, the angular difference of the four opening positions of the points must n.ot
3 exceed lo I 21n.xint~lm r/In/ oj distributor : 3250 I./)NI. c,.vcc,pt I)l’(.lit,t.tt~K 525 06X A : 2750
r/m 1,
c
E
!i
a
z 4. Ch k’ ec rng and adjusting the dwell angle :
Run the distributor at a steady speed, and check that the dwell angle is equal ;o 55’ ? 2”30’. If this is not the
case, adjust the contact breaker to obtain this condition.
5. Checking the ignition condenser :
With the contact points open. measure the capacity of the condenser; This value must be 0.30 i 0.03 wF.
If this is not the case. replace the condenser.
6. Check the vacuum advance curve :
This check is carried out at a constant rpm of 200, with no centrifugal advance.
Check the points of the increasing curve. and the decreasing curve. If the vacuum capsule has n hathcr.
it will be necessary to blank it off during this check.

Downloaded from www.Manualslib.com manuals search engine OPERATION No MA. 210.0 : c l~vritis,e nvrl Provisionally position support plate (2 1 and
gently tighten nut ( 1 )
c) Switch on ignition
Connect a test lamp to earth and to the G RUP B)
terminal of the ignition coil.
Turn the distributor until the exact moment
when the indicator lamp liqhts up.
At this point the distributor is al the static
advance point.
Switch off the ignition.
Tighten nut ( 1 ) from 19 to 21 mN ( 1.9 to
2.1 m kq 1 ( 13 l/2 to 15 ft.lb 1.
Fit distributor cap and secure it
Fit sparking plug in cylinder No 1 2. Checking the ignition timing using a stroboscopic
Imp or (I test-bench
( See chapter I,, page 1 i.