3232842 - 1056B multi-point injection system (mpi)

VIEW OF ASSEMBLY
1, Electric fuel pump 2, Relays 3, Lambda probe (two stereo lambda probes for automatic transmission version) 4, Speedometer 5, Rev counter 6, Engine Check warning light 7, Throttle body integrated with D.V.E. 8, Timing sensor 9, Climate control connector 10, Diagnostic connector 11, Alfa Romeo CODE connector 12, Injection/ignition control unit 13, Injectors 14, Coolant temperature sensor 15, Rpm sensor 16, Air flow meter 17, Ignition coils 18, Detonation sensors 19, Fuel vapour recirculation solenoid valve 20, Accelerator pedal potentiometer (only for version with manual gearbox) 21, Clutch pedal switch 22, Brake pedal switch 23, Coolant temperature indicator warning light

ME2.1 injection/ignition control unit

The control unit is mounted in the interior compartment on the passenger side panel.The control unit's memory is "flash EPROM", i.e. reprogrammable from the outside without intervening on the hardware.

The replacement of the injection control unit or throttle body actuator means that the self-learning procedure has to be carried out:

  • ignition turned on for 30 seconds
  • remove key for 5 seconds
  • Start the engine.
PIN-OUT
A-1, Lambase sensor 2 heater (only for automatic transmission version) A-2, Supply A-3, Ignition earth A-4, N.C. A-5, Lambda sensor heater A-6, Relay for 1 st fan speed A-7, Ignition earth A-8, Electronic earth (for sensors) B-1, N.C. B-2, N.C. B-3, Programming B-4, Battery from C-1 to C-20, N.C. C-21, Fuel vapour recovery solenoid valve C-22, Supply for potentiometer - 1 accelerator pedal C-23, Earth for potentiometer - 1 accelerator pedal C-24, Signal for potentiometer - 1 accelerator pedal C-25, Signal for potentiometer - 2 accelerator pedal C-26, Earth for potentiometer - 2 accelerator pedal C-27, Supply for potentiometer - 2 accelerator pedal C-28, N.C. C-29, Fuel pump relay C-30, N.C. C-31, Lambda sensor earth C-32, Lambda sensor signal C-33, Lambda 2 probe signal (only for versions with automatic transmission) C-34, Lambda 2 probe earth (only for versions with automatic transmission) from C-35 to C-37, N.C. C-38, Rpm signal C-39, Diagnostic connection (line K) C-40, N.C. D-1, N.C. D-2, N.C. D-3, Relay for cooling fan 2 nd speed from D-4 to D-10, N.C. D-11, CAN line "high" D-12, CAN line "low" D-13, Speedometer signal D-14, Brake lights switch from D-15 to D-16, N.C. D-17, Automatic transmission recognition D-18, N.C. D-19, Clutch pedal switch from D-20 to D-24, N.C. E-1, Operation of injector for cyl. 3 E-2, Operation of injector for cyl. 6 E-3, N.C. E-4, Air conditioning compressore relay feed from E-5 to E-12, N.C. E-13, Operation of injector for cyl. 2 E-14, Operation of injector for cyl. 5 E-15, Request to engage 1st fan speed E-16, N.C. E17, Request to engage 2nd fan speed from E-18 to E-20, N.C. E-21, Air conditioning request switch E-22, N.C. E-23, N.C. E-24, N.C. E-25, Operation of injector for cyl. 1 E-26, Operation of injector for cyl. 4 E-27, N.C. E-28, Coolant temperature sensor earth E-29, Coolant temperature sensor signal E-30, N.C. E-31, Potentiometer - 1 butterfly casing E-32, Earth for potentiometer 1-2 butterfly casing E-33, Supply for potentiometer 1-2 butterfly casing E-34, Potentiometer - 2 butterfly casing E-35, N.C. E-36, N.C. E-37, Rpm sensor (-) E-38, Rpm sensor (+) E-39 Timing sensor earths E-40, Timing sensor signal E-41, Earth for detonation sensor 1 (cylinders 1-4-5) E-42, Signal for detonation sensor 1 E-43, Earth for detonation sensor 2 (cylinders 2-3-6) E-44, Signal for detonation sensor 2 E-45, Air temperature sensor E-46, Flow meter - reference voltage 5V E-47, Output voltage (signal) - flow meter E-48, Earth - flow meter F-1, Throttle body motor integrated with D.V.E. F-2, Throttle body motor integrated with D.V.E. F-3, N.C. F-4, N.C. F-5, Operation of ignition coil for cyl. 6 F-6, Operation of ignition coil for cyl. 2 F-7, N.C. F-8, Earth from F-9 to F-12, N.C. F-13, Operation of ignition coil for cyl. 4 F-14, N.C. F-15, N.C. F-16, N.C. F-17, Operation of ignition coil for cyl. 3 F-18, N.C. F-19, Operation of ignition coil for cyl. 5 F-20, Operation of ignition coil for cyl. 1 F-21, Operation of injection warning light

Injectors

The single-jet fuel injectors are installed on the distribution manifold and are pressed by the manifold itself into their respective seats in the inlet ducts.A retainer secures the fuel injector to the distribution manifold, and two O-rings ensure the seal.The fuel injectors are responsible for delivering the necessary quantity of fuel to the engine.They are "all or nothing" devices, as they can remain in only two stable states, i.e. open or closed. They allow fuel to pass when they are open, while they block delivery when they are closed.

Operation

They basically consist of a nozzle controlled by a solenoid and a return spring (4).In the rest position, the pintle (2), which is joined to the core (3), is pushed by the spring onto the injector nose (6), thus closing the hole, ensuring a seal and preventing the unrequired emergence of fuel.As soon as the winding (5) is energized, the core is attracted, and it compresses the spring thus opening the hole of the nozzle and allowing fuel to emerge.Considering the physical characteristics of the fuel (viscosity, density) and the pressure drop (via the pressure regulator) to be constant, the quantity of fuel injected depends only on the fuel injector opening time.The winding energization time is normally indicated as "fuel injection time".
1, Injector body 2, Pintle 3, Magnetic core 4, Coil spring 5, Winding 6, Injector nose 7, Adjustable spring pusher 8, Filter 9, Electrical connection 10, Seal For operating checks  See Test 1056B  Check injector efficiency .

Engine coolant temperature sensor

This is mounted on the thermostatic cup, and it measures the coolant temperature by means of an NTC thermistor with a negative resistance coefficient.
The sensor is made using semiconductor technology, so if the sensor temperature increases as the coolant temperature increases, its resistive value decreases.As the variation in resistance is not linear, for the same temperature increment, it is higher for low temperatures than for high temperatures.
1, NTC resistor 2, Sensor body 3, Supply connector For operating checks  See Test 1056B  Check on operation of engine coolant temperature sensor .

Detonation sensors

The piezoelectric type detonation sensors are fitted on the cylinder block/crankcase, between the two heads, and measure the intensity of the vibrations caused by the detonation in the combustion chambers.The piezoelectric crystal forming the sensor detects the vibrations generated at a frequency of between 12 and 16 kHz, and transforms them into electrical signals sent to the fuel injection control unit.The tightening torque for the bolt fixing the detonation sensors is 1.95 - 2.05 daNm.

Rpm and T.D.C. sensor

This is fitted on the cylinder block/crankcase, "facing" the phonic wheel on the engine flywheel.It is of the inductive type, i.e. it functions by means of the variation in the magnetic field generated by the passage of the teeth of the phonic wheel (60-2 teeth).

The fuel injection control unit uses the rpm sensor to:

  • determine the speed of rotation
  • determine the angle of the crankshaft.

Operation

The passage from full to empty, due to the presence or absence of the tooth, causes a variation in the magnetic flow which is sufficient to generate an induced alternating voltage, resulting from the count of teeth located on a ring (or phonic wheel).The frequency and range of the voltage sent to the electronic control unit provides it with the crankshaft angular speed.
1, Brass bush 2, Permanent magnet 3, Plastic sensor casing 4, Coil winding 5, Polar core 6, Toothed or phonic wheel 7, Coaxial two-wire cable or electrical connection The specified gap for obtaining correct signals, between the end of the sensor and the phonic wheel, must be between 0.8 and 1.5 mm.This gap is not adjustable, so if a value outside the tolerance range is measured, check the condition of the sensor and the phonic wheel.
1, Maximum magnetic flow 2, Minimum magnetic flow 3, Trend of induced alternating voltage For operating checks  See Test 1056B  Check altitude corrector efficiency .

Timing sensor

Hall effect, it is fitted on the right cylinder head "facing" the disc on the rear of the exhaust camshaft for the right cylinder head.The disc contains a peg which allows the sensor to signal the engine timing position.The fuel injection control unit uses the timing sensor's signal to find out the TDC at the end of compression.

Operation

A semiconducting layer, through which current passes, immersed in a perpendicular magnetic field (force lines perpendicular to the current direction), generates at its ends a difference in potential known as Hall voltage.Whilst the disc (1) rotates, when the tooth (3) passes over the sensor (2), it blocks the magnetic field with a consequent "low" output signal.Conversely, after the tooth (3) passes the sensor (2), the signal becomes "high".Consequently the high signal alternates with the low signal every two engine revolutions, to be precise when cylinder no. 1 is 58° before TDC.
1, Camshaft disc 2, Timing sensor 3, Tooth

Accelerator pedal potentiometer

The accelerator pedal is fitted with two integrated potentiometers:

  • one main
  • one safety.

The injection control unit implements the following "recovery" strategies

  • if there is a fault with one of the two potentiometers, a throttle opening of up to 40° is allowed for a long period
  • if both of the potentiometers fail completely, the throttle opening is excluded.
The accelerator pedal is adjusted by excluding the end of travel (this position should not be exceeded).

Operation

The sensor consists of a casing (1), fixed to the pedals by a flange, which contains a shaft (2), in an axial position, connected to the two potentiometers (3).There is a coil spring on the shaft which guarantees the correct resistance to the pressure whilst a second spring ensures the return on release.Operating range from 0° to 70°; mechanical cut out at 88°.
For operating checks  See Test 1056B  Check operation of accelerator pedal potentiometer .

THROTTLE BODY INTEGRAL WITH D.V.E.

It is fitted on the inlet chamber and regulates the quantity of air drawn in by the engine.According to the signal coming from the accelerator pedal potentioemter, the injection control unit controls the opening of the butterfly by mens of a direct current motor integrated in the butterfly casing integrated with D.V.L.Throttle opening takes place between 0° and 80° therefore
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