3308467 - 1056B multi-point injection system (mpi) (Automatic transmission)
VIEW OF ASSEMBLY
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GENERAL CHARACTERISTICS
Operation of the fuel injection-ignition
The Bosch Motronic ME2.1 system with a motorized butterfly belongs to the category of integrated systems with:
- ignition
- sequential and timed electronic injection.
The main operating principles of the sytem are basically as follows:
- self-learning;
- system self-adaptation;
- autodiagnosis;
- recognition of the Alfa Rome CODE (Immobilizer);
- control of cold starting;
- control of combustion - Lambda sensor;
- control of detonation;
- control of mixture enrichment during acceleration;
- fuel cut-off with accelerator pedal released;
- fuel vapour recovery;
- control of maximum engine speed;
- control of fuel pump;
- connection to the climate control system;
- recognition of cylinder position;
- control of optimum injection time for each cylinder;
- adjustment of ignition advance values;
- managment of idle speed (also according to the battery voltage);
- managment of the butterfly opening law (Sport throttle response);
- management of the turbocharger;
- control of the electric fans;
- control of the Cruise Control system (where fitted);
- connection with the ABS control unit;
- connection with the instrument panel.
Fuel injection system
The essential conditions that must always be met in the preparation of the air-fuel mixture for the correct operation of controlled-ignition engines are mainly:
- the "metering" (air/fuel ratio) should be kept as close as possible to the stoichiometric raio so as to ensure the maximum conversion capacity of the catalytic converter (max. efficiency).
- the "homogeneity" of the mixture, consisting of petrol vapours, diffused as finely and evenly as possible in the air.
The information processed by the control unit for controlling optimum metering is received in the form of electrical signals emitted by the:
- air flow meter and air temperature sensor, for the exact quantity of air drawn in
- rpm sensor, which generates an alternating single-phase signal whose frequency indicates the engine rpm
- butterfly potentiometer, to recognize the required acceleration conditions
- coolant temperature sensor located on the thermostat
- Lambda sensor for determining the oxygen content in the exhaust gases
- barometric altitude sensor.
Ignition system
The ignition system is the static advance lost spark type (i.e. with no high tension distributor) with the ignition module integrated with three coils with six outlets.Stored in the control unit, there is a map containing the entire set of optimum ignition advance values (for the cylinder at the power stroke) that the engine can adopt in relation to the rpm and required engine load.The control unit corrects the advance values mainly in accordance with the:
- engine rotation speed
- engine load
- engine coolant temperature
- intake air temperature
- detonation.
The information which the control unit processes to operate the ignition coil is received by means of electrical signals emitted by the:
- air flow meter and air temperature sensor, for the exact quantity of air drawn in
- rpm sensor, which generates an alternating single-phase signal whose frequency indicates the engine rpm
- detonation sensors, (on the upper part of the cylinder block/crankcase between the two heads) to recognize the cylinder where detonation is occurring and correct the ignition advance
- butterfly potentiometer, to recognize the idle, choke and full load conditions.
OPERATION
Diagram of input/output information to/from the control unit
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SYSTEM OPERATING LOGICS
Self-learning
The control unit implements the self-learning logic in the following conditions:
- removing-refitting or replacement of the injection control unit
- removing-refitting or replacement of the integrated butterfly with D.V.L.
System self-adaptation
The control unit has a self-adaptation function which recognizes changes in the engine which occur as a result of bedding-in and ageing processes of both components and the engine itself.There are two adaptation functions according to two intervention plans: idle and usage.
Autodiagnosis
The control unit's self-test checks the signals coming from the sensors, comparing them with the permitted limits:indication of starting faults
- warning light on for 4 secs indicates test stage
- warning light off after 4 secs indicates no faults in components that could affect the values established in emission control regulations
- warning light on after 4 secs indicates fault
fault indication during operation
- warning light on indicates fault
- warning light off indicates no faults in components that could affect the values established in emission control regulations
recovery:
- the control unit defines as and when required the type of recovery depending on the faulty components
- the recovery parameters are managed by non-faulty components.
Recognition of the alfa romeo code
When the control unit receives the ignition "ON" signal, it dialogues with the Alfa Romeo CODE control unit to obtain starting enablement.
Check on cold starting
The following occurs during cold starting:
- natural weakening of the mixture because of poor turbulence of the fuel particles at low temperatures
- condensation of the fuel on the inner walls of the inlet manifold
- higher viscosity of the lubricating oil.
The electronic control unit recognizes this condition and corrects the fuel injection times in accordance with:
- coolant temperature
- intake air temperature
- battery voltage
- engine rpm
Check on combustion - lambda sensor
According to the engine speed and load conditions, the control unit processes the Lambda sensor signal and determines the injector opening times.
Control of detonation
The control unit can delay ignition, selectively at the cylinder required, according to the combination of figures received from the detonation and timing sensors and can reduce the ignition advance in steps of 2° 25' up to a maximum of 9° and update the threshold value to take the following into account:
- background noise;
- ageing of the engine.
With the auto-adjustment function, the control unit:
- memorizes the various advance reductions, continuously repeated
- adapts the map to the different engine conditions.
Recovery:
- – in the case of fault with the timing sensor or the detonation sensor or the injection control unit, the ignition is delayed according to the engine temperature and speed. The maximum ignition delay is always below 9° engine.
Control of mixture enrichment during acceleration
When there is a considerable acceleration request, the control unit modifies the injection time and the position of the butterfly.Recovery:
- the control unit replaces the signal coming from the faulty air flow meter with the signal from the potentiometer integrated in the butterfly casing integrated with D.V.L.
Fuel cut-off when the accelerator pedal is released
When the control unit:
- recognizes the idle condition
- with the engine speed above a certain threshold
it deactivates the fuel injection according to the:
- engine speed
- engine temperature
- vehicle speed.
Fuel vapour recovery
The (polluting) fuel vapours, collected in an activated-charcoal filter (canister), are sent to the inlet ducts to be burnt.This takes place via a solenoid valve operated by the control unit which keeps it closed for 60 seconds after starting and then opens it for 90 seconds.During this period (90 seconds), the Lambda sensor measures the carburation which is compared by the control unit with the basic map.If there are no variations, the control unit closes the solenoid valve, otherwise it keeps it open for a further 90 seconds allowing the washing of the canister.Nominally the filter washing flow rate is limited to a small percentage of the air flow rate meter reading so that the adjustment plan is as balanced as possible and the driveability of the vehicle is disturbed as little as possible.
Control of the maximum engine speed
Depending on the rpm reached by the engine, the control unit:
- beyond 6440 rpm the supply is removed from the injectors (it is permitted to reach a maximum of 6520 rpm for a maximum of 3 secs).
- below 6400 rpm the operation of the injectors is resumed.
Control of the fuel pump
The control unitsupplies the electric fuel pump:
- with the key in the ON position (for 5 secs)
- with the key in the AVV (starting) position and the engine speed > 25 rpm.
interrupts the supply to the electric pump:
- with the key in the OFF position
- with the engine speed < 25 rpm.
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