turn Citroen CX 1985 1.G User Guide

Downloaded from www.Manualslib.com manuals search engine INJECTORS ( i ) :
Each cylinder is supplied by an electro-magnetically controlled injector which is fitted in the inlet duct;
the injector vaporises the fuel upstream of the inlet valve. In the case of the (( L-Jetronic )) system. all the
injectors operate simultaneously. However, in order to ensure regular fuel supply to the cylinders, there are
two injections for each rotation of the camshaft, each one supplying half the metered quantity of fuel required I
for the complete engine cycle.
The injector consists of a valve housing and an injector needle fitted with a magnetic core. The mobile magnetic
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core is in one piece with the needle which in turn is compressed against the air-tight injector housing seat by
a helicoidal spring. At the rear end of the injector, there is a solenoid. and at the front a guide for the injector
needle.
Impulses coming from the E.C.U. create a magnetic.field in the solenoid; the magnetic core is attracted, and the
needle lifts off its seat the fuel under pressure is free to pass through, The movement of the magnetic core is
approximately 0.15 mm.
The duration of opening is determined by the E.C.U. as a function of the operating conditions of the engine at the
moment in question{. TEMPERATURE SENSORS t(
When the engine is started, for a temperature of approximately - 20” C, it needs two to three times more fuel than
when it has reached normal operating temperature. The enrichment of the mixture must be reduced as the engine
warms up, and must cease as soon as the engine has reached normal operating temperature. In’order to start off
this regulating procedure, the engine temperature must be communicated to the E.C.U. ( Electronic Control Unit ).
This is the object .of the temperature sensors.
The temperature sensor consists of a hollow threaded rod in which is located an NTC Thermistor made in semi-
conducting material. The letters .NTC, which signify (( negative temperature coefficient )) characterise its specific
property : its electrical resistance decreases as the temperature increases.
The (( L-Jetronic 1) system is fitted with.a water temperature sensor ( 2) and an air temperature sensor, the latter
situated in the air-flow sensor.

Downloaded from www.Manualslib.com manuals search engine Op. MA.IE. 144.00 19
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One-way valve
Safety valve
PRESSURE REGULATOR
Id.17
t Return to tank

Downloaded from www.Manualslib.com manuals search engine 5. Air-flow sensor ( DIAGRAM 5 )
- Disconnect the E.C.U.
- Using an ohmmeter check the continuity of circuits (( 6 )a, H 7 )) (( 8 H and (( 9 )) linking the air-flow sensor to
the multiple terminal board. as well as the continuity between each of the terminals
- The air-flow meter does not require any maintenance. It is not necessary to oil the flop. It must work without
high spot or catching
When the air-flow sensor is removed blank off the ducts so OS to protect it from dust
- Check the air circuit for air-tightness.
6. Resistors and injectors :
- A dirty injector may cause o lock of power. or on unstable idling speed.
- It is possible to test the functioning of the injectors with the engine idling by disconnecting each injector
in turn the engine rpm should decrease each time.
- Disconnect the E C U
- The resistance of an injector is 2 to 3 II.
- Each supplementary resistance is 5 to 7 R
- The volume delivered by an injector ( kept constantly open and under the normal operating pressure ) is
approximately 200 cm3 /min ( 12 25 cu in/min )-
- If the rubber pipe on one of the injectors appears wet on the outside, the injector must be replaced.
- Using an ohmmeter, check the continuity of the circuits

Downloaded from www.Manualslib.com manuals search engine OPERATION No MA.IE. 144-0 : (,hcrkir~g m/cl nrl;tts/ir/<~ I/W a I.-J~~/m,i~ ~~otectrot,ic Op. MA.IE. 144-O 25 fi~cl irijection systc~rti.
ANNEXE : A - CHECKING THE IGNITION
THE ENGINE TURNS, BUT DOES
NOT FIRE

Downloaded from www.Manualslib.com manuals search engine 28 OPERATION N” MA.IE. 144-O : Ch <,c ,ng n,,d nlfjusfiup Ihe u I.-~<~tro,,ir i) <~lrr/mr,ir k’
/,,,.I i,,jrr/io,, S~S,W1, ANNEXE : D - ADJUSTING THE IDLING SPEED AND THE EXHAUST EMISSION
CHECKING CONDITIONS
1.
Checking the idling speed must be carried out
on a clean engine on which the ignition and the
valve clearances are properly adjusted and
fitted with a clean air-filter.
2. Check that the throttle butterfly returns correctly
to its stop.
3. Do not load the alternator by switching an any
of the electrical components, except the iqnition
and the electric cooling fan (s) 4.
Run the engine to bring the oil temperature up
to 70 +o 80’ C ( wait for the electric cooling
fan is) to cut in ). IMPORTANT : Use exclusively (I high tension
tachometer ( do not damage the H.T. lead of
the ignition wiring harness ).
ADJUSTMENT
1. Check that the butterfly is not jammed in position
when it is resting against its stop.
2. Wait for the electric cooling fan (s) to cut in.
3. Use screw ( 1 ) to adjust the idling speed to 850
to 900 rpm.
4. Check the exhaust emission :
The resulting amount of CO - CO2 ( corrected CO
reading 1 must be beI& 4.5 %.
In case this reading cannot be obtained, check the
valve clearances, the ignition, the fuel pressure,
the air-tightness of the aircircuit, and the complete
fuel injection system.
5. On (I vehicle fitted with optional oirtonditioning
switch the compressor on, and adjust the idling
speed from 1000 to 1050
rpm, by adjusting the
screw on the auxiliary box located next to the
electro-vol”e.

Downloaded from www.Manualslib.com manuals search engine OPERATION No MA. 173-O : Chrrkivp fhr prmd s,,pp/> Op. MA. 173.0 1
PETROL PUMP
AC DELCO pump reference E/PE 4.777
Auto-regulating diaphragm lift and force pump
operated by eccentric on camshaft.
This pump is fitted with (I device which enables it
to function on re-cycled petrol. This re-cycling is
effected by means of a by-pass .( 1 ) fitted on the
carburettor cover.
Excess petrol supplied by the pump returns to the
tank across an orifice calibrated from 0.8 to 0.9mm
in the by-pass union (1).
PETROL PUMP OUTPUT
(I) Otitput nil, maximum pressure : 325 mbars (4 7 psi).
b) Output through open carburettor float needle
valve.
500 45 88
3000 65 170
5500 69.5 192
I I
Minimum pressure
in mbors
INSTALLATION OF PETROL PUMP
Fitted on the crankcase with :
one (( Phenoploste P12 )) spacer 5 + 0.1 mm thick.
two (< SOCOID a> paper gaskets fitted dry.
Tightening torque for petrol pump nuts :
21 mN ( 2.1 m.kg ).( 15 l/4 ft.lb )
CHECKING THE STROKE OF THE PUMP PUSH-ROD
a) With the pump removed and using (I depth gouge A,
take the measurement between the upper face of
the spacer ( with paper joints ) and the camshaft
eccentric in its high position and in its low
position.
This measurement should be :
- Upper position of eccentric 27.4 ? 0.35 mm
- Lower position of eccentric 32.4 rk 0.35 mm
b) Measure the length u a a) between the spring stop cup
and the tip of the pump control push-rod.
This length should be :
a = 4.5 mm minimum

Downloaded from www.Manualslib.com manuals search engine 2 OPERATION No MA. 173.0 : C/ l<,C ,,,g //JP p/r”/ SuppI) k’
CHECKING THE PETROL PRESSURE USING APPARATUS 4005-T
Install apparatus 4005-T as shown above.
Disconnect reservoir return line from the carburettor and fit plug A on by-pass union ( 1 1.
Unscrew knurled knob B by approximately one and a half turns.
Start the engine
a) Check pressure of petrol at nil output :
b
c -Fully screw down knurled knob B and read the stabilized pressure on the pressure gouge which should
be 325
mbors ( 47 psi ) maximum.
Check the proper sealing of the pump return valve
-Stop the engine. There should be no sudden drop in pressure
Check the proper sealing of the carburettor needle valve :
- Unscrew knurled plug B and start the engine. Let it run for a few minutes.
-Stop theengine.
There should be no sudden drop in pressure.
= Remove apportus 4005=T and fit to carburettor the tank supply and return pipes (after having removed plug A 1:
CHECKING THE PUMP FOR LEAKS
- Close the pump return pipe.
-- Blow compressed air under pressure of 800 mbar
( 11.6 psi ) into Suction tube.
Immerse pump in a container filled with clean
petrol.
There should be no sign of dny leak.
Work on petrol gauge sender unit :
To work on the petrol gouge sender unit it is
necessary to drain the tank (drain plug 1, and
~emcwe it. It is held by double strap fixed by
nut (2 1.
Tightening of nut (2) = 15 mN ( 1.; m.kg )
( 10 3/4 ft.lb ).

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.