1985 Citroen CX CAM sensor

Downloaded from www.Manualslib.com manuals search engine I. CHARACTERISTICS
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5 Cooling system : Water cooled.
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T cx 2000 cx 2200 CX 2400 and Prestige
CX 2400 GTI
- Type ( on engine p’late ) : _..._................... M 20/616 M 22/617 M 23/ 623
M 23/622
Cubic capacity : . . .._......_...............
1985 cc 2175 cc 2350 cc 2350 cc
Transversely mounted, inclined
300 towards the front
Number of cylinders : _........................... 4 (iI/ linr, J 4 Iin linr,)
4 (irr /iUP J 4 f in lin i’ ,
Bore : 86 mm 90 mm 93.5 mm 93.5 mm
- Stroke : .,.,,_,.,.,....____.,.. .._._.....................
85.5 mm 85.5 mm 85.5 mm
85.5 mm
Compression ratio :
9/I 9/l 8.7511 8.7511
Maximum power ( DIN ) : . . . .._................... 102 bhp at 5500 rpm 112 bhp at 5500 rpm 115 bhp ot 5500 rpm
128 bhp at 4800 rpm
Maximum torque (DIN)
: . . 15.5 m.kg (112 ft.Ib ) 17 m.kq (123 ft.Ib) 18.2 m.kg ( 132 ft.Ib)
20.1 mkq (145 ft.Ib)
at 3000 rpm at 3500 rpm at 3000 rpm
at 3600 rpm
Maximum engine rpm in 4th gear :
* 13/62 final drive rtrtio :
5600 rpm 5800 rpm 5900 rpm
*14/61 final drive ratio ( -1 1’175 J 4600 rpm
Maximum engine rpm in 5th gear
(
13,‘62 final drive ratio ) : ,._............,..,........,....,.,........,..,.,..... .._.........,................ .._..._...................
5600 rpm
* NOTE : For CX 2200 and CX 2400 vehicles fitted with a torque converter, the maximum rpm in 3rd gear is 5600 rpm.
: Lubrification :
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Under pressure, supplied by o gear-type oil-pump driven by the camshaft.
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External oil filter cartridge ( PURFLUX, LS 105 type ).
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i Fuel supply :
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i a) Engines fitted u~ifh a rnrbuwffor
WEBER compound-type twin choke carburettor (s.ee Operations MA. 142-00, 142-00 a, 142-00 b far the type, and the identification marks )
Dry-type air filter, with filter cartridge.
Mechanical fuel pump, driven by on eccentric on the camshaft.
b) i?ugi,jes ji/f.rd II ith /LIP/ iniPr/ioo :
BOSCH L-Jetronic electronic fuel injection system
Grade of pet,ol to be used : > ._,,,,.,_.._,,,,,.,......... . .._...o....._............................................. K.
99 Orrani ralrrig (FRANCE : Super grade ) (U.K. : 4-star )
Ignition :
Distributor ( DUCELLIER or MARELLI ) driven by the camshaft.
NOTE : The M 23/622 engine with fuel injection is fitted with (I DUCELLIER distributor with a magnetic sensor, and an u AC-DELCO /a electronic module.
- Spark pluqs : .................................................................................................................................... shorf warh
Firing o&r : .................................................................................................................................... 1 - 3 - 4 - 2 f tbu cylinders ale INR&Cd 011 the roc6w COI rr,
Timing :
Side mounted camshaft located in crankcase.

Downloaded from www.Manualslib.com manuals search engine OPEdATlON N- MA.IE. 144-00 : C1 3aractcJristics o/ the e L-Jetro~ic n elcctrorlir Op. MA.IE. 144-00 9
fuel injectian systwn. E.C.U; ( ELECTRONIC CONTROL UNIT )
Apart from three integrated circuits ( I.C. ) forming the main part of the E.C.U., there are in addition only a few
semi-conducting components condensers, calibrating resistors and filters so as to avoid.any interference.
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The function of the E.C.U. is ,to supply an impulse to the injectors, and to control their opening for a precisely
defined amount of time. The E.C.U. to this effect uses the information provided by all the engine sensors which
translate the operating conditions of the engine into electric impulses.
All the injectors are connected in parallel, and inject fuel simultaneously twice for each rotation of the camshaft
( therefore,twice for each engine cycle ), injecting half the quantity of fuel required each time With this system
it is not necessary for the camshaft angle to coincide with the beginning of injection point, which eliminates the
need for a generating switch incorporated in the distributor.
The injection impulse control is ensured by the distributor impulses. The distributor produces four impulses for
every operational cycle. Since injection only occurs twice in every cycle, the E.C.U. must divide the frequency
by 2.
The impulses coming from the distriLti, are transformated into square waves by the waveform shaper. Since
injection only occurs twice for each camshaft rotation, whereas the distributor provides 4 impulses in the same
amount of time, the frequency of the impulses must be divided by 2 in the frequency divider.
These signals are used to charge a condenser. The condenser discharge determines the beginning of injection
point; the position of the air-flow sensor flap ( which determines the quantity of air drawn in ) being the main
parameter for calculating the duration of injection.
At the multiplying stage of the E.C.U., various correction values ( full load and idling speed via throttle butterfly
spindle switch, engine temperature via the water temperature sensor, air temperature via the air-temperature sensor
located in the air-flow sensor ) are combined with the signals from the air-flow sensor and the injt,ztion frequency
in order to determine the injection duration which is transmitted to the injectors by way of impulses.
The time it takes for the injector needle to open and close depends on the battery voltage.
As the supply voltage increases, the injection duration increases.
The fact that the quantity of fuel injected depends
on the voltage is cancelled out by the fact that the injection duration is inversely proportional to the voltaqq,in the
E.C.U.
The final impulse determines the time during which the injectors are connected to earth ( injection duration ‘supplied
by the output stage ).

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 OPERATION No MA. 210-W 0 : Ch araclcrislics ~3rd spcial /W~~NWS 0j thr d~~fmt~i~ Op. MA. 210-00 a 1
ipith syslwn.
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M 23/622 ENGINE
TRANSISTORISED IGNITION WITH ELECTROMAGNETICALLY CREATED IMPULSES
$ OPERATING PRINCIPLE
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,D The electronic ignition comprises a coil ( 1 1. (I transistorised module ( 2) which includes among other components.
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.f a power transistor working as a contact breaker.
and a distributor (3 1 with a magnetic pick-up ( impulse generator )
and an H.T. rotor.
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F The primary current from the coil goes through a switching transistor situated in the module ( the earthing is carried
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out via the fixing bracket for the coil mrd module assembly ).
As an impulse is created by the sensor in the distributor. it switches off the transistor and thus cuts off the flow
of current in the coil primhry circuit. which causes a (< High Tension 1) current in the coil secondary circuit.
The module is located in the distributor..replocinq the contact breaker unit in a conventional ignition system. It
comprises a sensor (4) and a 4-point star ( 5 ).
The,sensor has a permanent moqnet inside a winding. This windinq is connected electrically to the module
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The 4-point star is made of metal. and has one star per cylinder. It is fitted in place of the rotor mm cam in (I
conventional ignition system.