3239194 - Introduction - ENGINE

GLOSSARY

GLOSSARY

Engine with 4 cylinders in line, double ignition, 16 valves, 1598 cc, twin overhead cam, electrohydraulic timing variator, with Bosch Motronic M2.10.4 integrated electronic fuel injection-ignition.

Description

General characteristics

The unit comprises the engine and all the systems required for its operation:

  • fuel supply system
  • air supply system
  • engine cooling system
  • exhaust system with catalytic converter
  • fuel vapour recirculation system.
The operation of these systems is optimized by an electronic control system governed by a control unit.Operation of the fuel injection-ignition

The Bosch Motronic M2.10.4 system belongs to the category of integrated systems:

  • inductive discharge digital electronic ignition
  • static distribution
  • sequential phased electronic fuel injection (1 - 3 - 4 - 2).

During idling, the control unit checks:

  • the moment of ignition
  • the air flow
with the benefit of maintaining correct operation of the engine when the environmental parameters and the applied loads vary.The control unit controls and manages fuel injection so that the stoichiometric ratio (air/fuel) is always at the optimum value.

System functions are essentially as follows:

  • adjustment of fuel injection times
  • adjustment of ignition advance values
  • check on cold starting
  • check on enrichment during acceleration
  • fuel cut-off during overrunning
  • check and management of idle speed
  • limitation of maximum rpm
  • check on combustion - Lambda probe
  • recognition of cylinder position
  • fuel vapour recovery
  • connection to air conditioning system (if present)
  • connection to Alfa Romeo CODE (Immobilizer) control unit
  • system self-adaptation
  • autodiagnosis
  • check on electric cooling fan
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) must constantly be kept as close as possible to the stoichiometric ratio, so as to ensure the necessary rapidity of combustion, avoiding unnecessary fuel consumption
  • 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:

  • 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
  • throttle position potentiometer (mounted on the throttle body), for recognizing the required acceleration conditions
  • coolant temperature sensor located on the thermostat
  • Lambda sensor for determining the oxygen content in the exhaust gases.
Ignition systemThe ignition is of the inductive discharge type, distributorless, with power modules located in the fuel injection control unit.

The system has a single coil for each plug (MONOCOIL); the advantages of this solution are:

  • less electrical overload;
  • guaranteed constant discharge on each plug.
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:

  • engine coolant temperature
  • intake air temperature
  • detonation
  • throttle valve position.

The information the control unit processes in order to drive the single coils 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
  • knock sensor (on the rear of the engine block between the 2nd and 3rd cylinders) which recognizes which cylinder is knocking and corrects its ignition advance
  • throttle valve position potentiometer (mounted on throttle body), which recognizes the minimum load, choke and full load conditions.

Description

General characteristics

The unit comprises the engine and all the systems required for its operation:

  • fuel supply system
  • air supply system
  • engine cooling system
  • exhaust system with catalytic converter
  • fuel vapour recirculation system.
The operation of these systems is optimized by an electronic control system governed by a control unit. An understanding of the operating logic of the control unit gives an overall picture of the entire GROUP 10 system (  See assembly 10   ENGINE ). Operation of the fuel injection-ignition

The Bosch Motronic M1.5.5 system belongs to the category of integrated systems:

  • inductive discharge digital electronic ignition
  • static distribution
  • sequential phased electronic fuel injection (1 - 3 - 4 - 2).

During idling, the control unit checks:

  • the moment of ignition
  • the air flow
with the benefit of maintaining correct operation of the engine when the environmental parameters and the applied loads vary.The control unit controls and manages fuel injection so that the stoichiometric ratio (air/fuel) is always at the optimum value.

System functions are essentially as follows:

  • adjustment of fuel injection times
  • adjustment of ignition advance values
  • check on cold starting
  • check on enrichment during acceleration
  • fuel cut-off during overrunning
  • check and management of idle speed
  • limitation of maximum rpm
  • check on combustion - Lambda probe
  • recognition of cylinder position
  • fuel vapour recovery
  • connection to air conditioning system (if present)
  • connection to Alfa Romeo CODE (Immobilizer) control unit
  • system self-adaptation
  • autodiagnosis
  • check on electric cooling fan
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) must constantly be kept as close as possible to the stoichiometric ratio, so as to ensure the necessary rapidity of combustion, avoiding unnecessary fuel consumption
  • 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:

  • 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
  • throttle valve position potentiometer (built into constant idle speed actuator), which recognizes the idle, choke and full load conditions.
  • Lambda sensor for determining the oxygen content in the exhaust gases.
Ignition systemThe ignition is of the inductive discharge type, distributorless, with power modules located in the fuel injection control unit.

The system has a single coil for each plug (MONOCOIL); the advantages of this solution are:

  • less electrical overload;
  • guaranteed constant discharge on each plug.
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:

  • engine coolant temperature
  • intake air temperature
  • detonation
  • throttle valve position.

The information the control unit processes in order to drive the single coils 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
  • knock sensor (on the rear of the engine block between the 2nd and 3rd cylinders) which recognizes which cylinder is knocking and corrects its ignition advance
  • throttle valve position potentiometer (built into constant idle speed actuator), which recognizes the idle, choke and full load conditions.

OPERATTION

Diagram of input/output information to/from the control unit
1, Intake air temperature sensor 2, Timing sensor 3, Throttle valve position potentiometer 4, Lambda probe 5, Speedometer 6, Engine water temperature sensor 7, Detonation sensor 8, Rpm sensor 9, Quadrinary 10, Flowmeter 11, Battery 12, Alfa Romeo CODE 13, Diagnostic socket 14, Timing variator 15, Ignition coils 16, Idle speed actuator 17, Check Engine warning light 18, Fuel injectors 19, Electric Fuel pump 20, Air conditioner compressor 21, Fuel vapour recirculation solenoid 22, Rev counter 33, Electric fan

Operating strategy

System self-adaptationThe 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.These changes are stored in the form of modifications to the basic mapping, and their purpose is to adapt the operation of the system to the gradual alterations in the engine and components compared with their characteristics when new.This self-adaptation function also makes it possible to even out inevitable differences (due to production tolerances) in any replaced components.From the exhaust gas analysis, the control unit changes the basic mapping in relation to the original characteristics of the new engine
AutodiagnosisThe control unit's self-test checks the signals coming from the sensors, comparing them with the permitted limits:signalling of faults during starting:

  • warning light on for 4 seconds indicating 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
Signalling of faults during operation

  • warninglight 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, from time to time, defines the type of recovery according to the faulty components
  • the recovery parameters are managed by non-faulty components.
Recognition of the alfa romeo codeWhen the control unit receives the ignition "ON" signal, it communicates with the Alfa Romeo CODE control unit to obtain starting enablement.Communication takes place via the dedicated bidirectional serial diagnostic line which connects the two control units.
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
  • lower evaporation of the fuel
  • 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.
The ignition advance depends solely on the engine rpm and the coolant temperature.During starting, the control unit controls a first simultaneous injection for all the injectors (full-group injection) and, after recognizing the timing of the cylinders, it starts normal sequential phased operation.During the engine warm-up stage, the control unit drives the idle speed actuator to regulate the quantity of air required to ensure the self-maintained rpm of the engine.The rpm is made to decrease in proportion to the increase in temperature of the engine until the optimum value with the engine up to temperature is obtained.
Check on combustion - lambda probe

The control unit, with the engine in the following conditions:

  • idle speed
  • medium load
processes, with a special integrator, the Lamba probe's signal and determines the fuel injector opening times.
Check on timing variatorIn accordance with the rpm, intake air flow rate and coolant temperature, the control unit checks and adjusts the intake timing (advance).The intake timing is varied by means of the electrohydraulic variator connected to the inlet camshaft.The control unit activates the variator when the engine rpm is higher than idle speed and does not exceed 4800 rpm, so as to provide the best performance.
Knock controlThe control unit detects the presence of knocking by processing the signal coming from the relevant sensor.The control unit continuously compares the signals coming from the sensor with a threshold value, which in turn is continuously updated to take account of background noise and ageing of the engine.The control unit is thus able to detect the presence of knocking (or incipient knocking) and reduces the ignition advance (in steps of 3° ?p t? a µa??µ?µ ?f 12°) ??t?? t?e ???????? d?sappea?s. The advance is then gradually restored to the basic value.Under acceleration conditions, a higher threshold is used to take account of the increased engine noise under such conditions.The detonation check logic also has a self-adaptation function, which memorizes the reductions in advance that may be repeated continuously, so as to adjust the mapping to the different conditions now affecting the engine.
Check on enrichment during accelerationIf during the acceleration demand, the variation in the air flow meter signal exceeds a predefined increment, the control unit increases the fuel injection time so that the required rpm is reached rapidly.When the established rpm is nearly reached, the increase in fuel injection is gradually eliminated.

Recovery:

  • the control unit replaces the signal coming from the faulty air flow meter with the signal from the throttle valve potentiometer.
Fuel cut-off during overrunning

During release of the accelerator pedal, and beyond a pre-established threshold, the control unit:

  • supply to the fuel injectors cut off
  • reactivates the supply to the fuel injectors at 1300-1500 rpm.
With throttle valve closed and engine speed exceeding 1700 rpm, the control unit inhibits the opening of the fuel injectors.As there is no fuel supply, the rpm decreases more or less rapidly depending on the vehicle's driving conditions.Before idle speed is reached, the trend of the fall in rpm is checked.If it exceeds a certain value, the fuel supply is partially reactivated so that the engine can "gently accompany" the drop towards idle speed.

The thresholds for reactivation of the fuel supply and for fuel cut-off vary depending on:

  • engine coolant temperature
  • vehicle speed
  • engine rpm.
Fuel vapour recoveryThe (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 controlled by the control unit only when the engine's operating conditions so permit.The control unit compensates for the additional quantity of fuel by reducing the delivery to the fuel injectors.
Limitation of the maximum rpm

Depending on the rpm reached by the engine, the control unit:

  • over 6800 rpm reduces the injection time
  • over 7000 rpm cuts off the supply to the fuel injectors
  • under 6800 rpm resumes driving of the fuel injectors.
Check on fuel-electric fuel pump supply

The control unit supplies the fuel pump:

  • when the ignition is ON for 0.8 s
  • when the ignition key is on START and the rpm > 225 rpm

The control unit cuts off the supply to the fuel pump:

  • ignition in OFF position
  • when the engine rpm < 225 rpm.
Connection to the climate control systemAt the power demand, following the switching on of the compressor, the control unit drives the idle speed actuator to increase the air flow.

During a high power demand, the control unit temporarily cuts off the supply to the compressor:

  • by switching it off over 6500 rpm
  • by switching it off if the engine temperature > 112° C.
Recognition of cylinder position

During each engine revolution, the control unit recognizes which cylinder is at the power stroke:

  • it controls the injection and ignition sequence for the appropriate cylinder.

In the absence of the timing sensor signal, the control unit:

  • deactivates the detonation sensor
  • with the car moving, maintains phased injection
  • with the car stopped, controls simultaneous ignition in cylinders 1-4 and 2-3.
Regulation of fuel injection times

The control unit calculates the injector opening times and controls them extremely quickly and precisely on the basis of:

  • engine load (rpm and air flow)
  • battery voltage
  • engine coolant temperature.
Fuel injection is sequential and phased for each cylinder, and takes place at the optimum "start-of-injection" point, while the "end-of-injection" point remains fixed.
Adjustment of ignition advance values

Thanks to the mapping stored in its memory, the control unit can calculate the ignition advance in accordance with:

  • engine load (idling, choke, full load depending on the rpm and air flow)
  • intake air temperature
  • engine coolant temperature
The ignition can be retarded selectively on whichever cylinder so requires, by combining the values recorded by the rpm and timing sensors.
Check - idle speed managementThe control unit, with throttle valve home and devices on (e.g. air conditioner compressor), regulates the idle speed (850 ± 30 ?pµ) ß? a?t??? ?? t?e ???sta?t ?d?e speed a?t?at??. This actuator, mounted directly on the throttle body, adjusts the throttle bypass gap in accordance with the command it receives from the control unit.In this way, the idle speed is kept as constant as possible, whatever the load applied to the engine (electrical, mechanical or hydraulic).
Check on radiator cooling fan

The control unit controls the switching on of the electric fan in accordance with the coolant temperature:

  • temperature for switching on 1st speed 93° C
  • temperature for switching on 2nd speed 98° C
There is a further check (quadrinary signal), which turns on the fan at high speed, if the air conditioning is switched on. In the absence of the coolant temperature signal, the control unit activates the recovery function and switches on the fan 2 nd speed until the error disappears.

OPERATION

Diagram of input/output information to/from the control unit
1, Electric fuel pump 2, Air conditioner compressor 3, Fuel injectors 4, Rev counter 5, Electric fan 6, Butterfly casing integrated with M.D.S. 7, Timing sensor 8, Speedometer 9, Lambda sensor 10, Coolant temperature sensor 11, Detonation sensor 12, Quadrinary 13, Rpm sensor 14, Debimeter integral with air temperature sensor 15, Battery 16, Alfa Romeo CODE 17, Diagnostic socket 18, Fuel vapour recirculation solenoid 19, Ignition coils 20, Phase transformer 21, Engine Check warning light 22, Modular inlet manifold solenoid (only 1.8/2.0 TS)

Operating strategy

System self-adaptationThe 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.These changes are stored in the form of modifications to the basic mapping, and their purpose is to adapt the operation of the system to the gradual alterations in the engine and components compared with their characteristics when new.This self-adaptation function also makes it possible to even out inevitable differences (due to production tolerances) in any replaced components.From the exhaust gas analysis, the control unit changes the basic mapping in relation to the original characteristics of the new engineThe self-adaptation parameters are not cancelled if the battery is disconnected.
AutodiagnosisThe control unit's self-test checks the signals coming from the sensors, comparing them with the permitted limits:Signalling of faults during starting :

  • warning light on for 4 seconds indicating 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
Signalling of faults during operation

  • warninglight 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, from time to time, defines the type of recovery according to the faulty components
  • the recovery parameters are managed by non-faulty components.
Recognition of the alfa romeo codeWhen the control unit receives the ignition "ON" signal, it communicates with the Alfa Romeo CODE control unit to obtain starting enablement.Communication takes place via the dedicated bidirectional serial diagnostic line which connects the two control units.
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
  • lower evaporation of the fuel
  • 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.
The ignition advance depends solely on the engine rpm and the coolant temperature.During starting, the control unit controls a first simultaneous injection for all the injectors (full-group injection) and, after recognizing the timing of the cylinders, it starts normal sequential phased operation.During the engine warm-up stage, the control unit drives the idle speed actuator to regulate the quantity of air required to ensure the self-maintained rpm of the engine.The rpm is made to decrease in proportion to the increase in temperature of the engine until the optimum value with the engine up to temperature is obtained.
Check on combustion - lambda probe

The control unit, with the engine in the following conditions:

  • idle speed
  • medium load
  • temperature > 30° C
processes, with a special integrator, the Lamba probe's signal and determines the fuel injector opening times.
Check on timing variator and modular inlet manifold

To optimize the quantity of air drawn in by the engine, the control unit checks:

  • inlet timing on two angle positions
  • geometry of intake ducts on two lengths (only 1.8/2.0 TS).

At the maximum torque speed, the control unit sets the "open" phase:

  • cam advanced by 25° engine
  • inlet casing long ducts (only 1.8/2.0 TS)

At the maximum power speed, the control unit sets the "closed" phase:

  • cam in normal position
  • inlet box short ducts (only 1.8/2.0 TS) .

A idle speed, the control unit sets the "closed" phase:

  • cam in normal position
  • inlet box short ducts.
In the other engine operating conditions, the control unit selects the most suitable configuration to optimize performance - consumption - emissions.During overrunning, the inlet ducts of the box are always "short" (only 1.8/2.0 TS) .
Knock controlThe control unit detects the presence of knocking by processing the signal coming from the relevant sensor.The control unit continuously compares the signals coming from the sensor with a threshold value, which in turn is continuously updated to take account of background noise and ageing of the engine.The control unit is thus able to detect the presence of knocking (or incipient knocking) and reduces the advance (in steps of 3° ?p t? a µa??µ?µ ?f 9°) ??t?? t?e ???????? d?sappea?s ??e ad?a??e ?s t?e? ??ad?a??? ?est??ed t? t?e ßas?? ?a??e (?? steps ?f 0.8°).Under acceleration conditions, a higher threshold is used to take account of the increased engine noise under such conditions.The detonation check logic also has a self-adaptation function, which memorizes the reductions in advance that may be repeated continuously, so as to adjust the mapping to the different conditions now affecting the engine.
Check on enrichment during accelerationIf during the acceleration demand, the variation in the air flow meter signal exceeds a predefined increment, the control unit increases the fuel injection time so that the required rpm is reached rapidly.When the established rpm is nearly reached, the increase in fuel injection is gradually eliminated.

Recovery:

  • the control unit replaces the signal coming from the faulty air flow meter with the signal from the throttle valve potentiometer.
Fuel cut-off during overrunning

During release of the accelerator pedal, and beyond a pre-established threshold, the control unit:

  • supply to the fuel injectors cut off
  • reactivates the supply to the fuel injectors at 1300-1500 rpm.
With throttle valve closed and engine speed exceeding 1700 rpm, the control unit inhibits the opening of the fuel injectors.As there is no fuel supply, the rpm decreases more or less rapidly depending on the vehicle's driving conditions.Before idle speed is reached, the trend of the fall in rpm is checked.If it exceeds a certain value, the fuel supply is partially reactivated so that the engine can "gently accompany" the drop towards idle speed.

The thresholds for reactivation of the fuel supply and for fuel cut-off vary depending on:

  • engine coolant temperature
  • vehicle speed
  • engine rpm.
Fuel vapour recoveryThe (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 controlled by the control unit only when the engine's operating conditions so permit.The control unit compensates for the additional quantity of fuel by reducing the delivery to the fuel injectors.
Limitation of the maximum rpm

Depending on the rpm reached by the engine, the control unit:

  • over 6800 rpm reduces the injection time
  • over 7000 rpm cuts off the supply to the fuel injectors
  • under 6800 rpm resumes driving of the fuel injectors.
Check on fuel-electric fuel pump supply

The control unit supplies the fuel pump:

  • when the ignition is ON for 0.8 s
  • ignition in AVV position and engine speed > 23 rpm

The control unit cuts off the supply to the fuel pump:

  • ignition in OFF position
  • with the engine rpm < 23 rpm.
The returnless fuel supply system ensures a constant petrol pressure of 3.5 bar.
Connection to the climate control systemAt the power demand, following the switching on of the compressor, the control unit drives the idle speed actuator to increase the air flow.

During a high power demand, the control unit temporarily cuts off the supply to the compressor:

  • by switching it off over 6500 rpm
  • by switching it off if the engine temperature > 112° C.
Recognition of cylinder position

During each engine revolution, the control unit recognizes which cylinder is at the power stroke:

  • it controls the injection and ignition sequence for the appropriate cylinder.

In the absence of the timing sensor signal, the control unit:

  • deactivates the detonation sensor
  • with the car moving, maintains phased injection
  • with the car stopped, controls simultaneous ignition in cylinders 1-4 and 2-3.
Regulation of fuel injection times

The control unit calculates the injector opening times and controls them extremely quickly and precisely on the basis of:

  • engine load (rpm and air flow)
  • battery voltage
  • engine coolant temperature.
Fuel injection is sequential and phased for each cylinder, and takes place at the optimum "start-of-injection" point, while the "end-of-injection" point remains fixed.
Adjustment of ignition advance values

Thanks to the mapping stored in its memory, the control unit can calculate the ignition advance in accordance with:

  • engine load (idling, choke, full load depending on the rpm and air flow)
  • intake air temperature
  • engine coolant temperature
The ignition can be retarded selectively on whichever cylinder so requires, by combining the values recorded by the rpm and timing sensors.
Check - idle speed managementThe idle speed condition is recognized by the control unit via the potentiometer built into the idle speed actuator, mounted on the throttle body (throttle spindle).

Depending on the devices switched on to control the idle speed (850 ± 30 rpm), the control unit:

  • varies the ignition advance
  • controls the throttle position (0°-15°) via the idle speed actuator, to regulate the air flow.
Check on radiator cooling fan

The control unit controls the switching on of the electric fan in accordance with the coolant temperature:

  • temperature for switching on 1st speed 98° C
  • temperature for switching on 2nd speed 101° C
There is a further check (quadrinary signal), which turns on the fan at 1st or 2nd speed, if the air conditioning is switched on, according to coolant pressure.In the absence of the coolant temperature signal, the control unit activates the recovery function and switches on the fan 2nd speed until the error disappears.