STRUCTURE AND OPERATION
2.2 Electronic injection system particular features of engines EPA 10
• To observe emission limits EPA 10, engines EPA 10 have following features:
• E.G.R. system present;
• D.P.F. filter (solid particulate trap with constant regeneration) present;
• New digital flow meter HFM7 (positioned after the air filter);
• Air pressure sensor present (on the intake manifold after the intercooler);
• Fuel electrical pump suitable to pressurize the circuit according to specifications Euro V;
• Vehicle wiring harness for central unit EDC 17 new electrical scheme;
• Exhaust brake valve present driven by EDC central unit (positioned on exhaust line).
• Constant regeneration particulate trap is mounted on engine exhaust. Through data processing (engine rpm’s,
H2O temperature, oil temperature, lambda probe signal, etc.), the central unit calculates the quantity of particulate
accumulated in filter and chooses to increase exhaust gas temperature (through post-injection) in order to burn
particulate accumulated inside filter.
• Further, vehicles (for compliance with regulations EPA 10) differ from the ones of present production mainly in fol-
lowing components:
• Fitting with catalytic converter DPF (Diesel Particulate Filter) provided with exhaust gas temperature sensors,
• Differential pressure (Delta-p) sensor for detecting DPF catalyst particulate filter clogging,
• Fuel electric pump with different characteristics for boosting fuel system pressurization,
• Electrical wiring harness.
• SCR
2.3 Fuel injection control
• The system calculates injection on the basis of the processing of the following parameters:
• Engine rpm.
• Engine coolant fluid temperature.
• Intake air capacity.
• Battery voltage.
• Fuel pressure.
• Accelerator pedal position.
• The fuel pressure in the common rail varies according to engine rpm and load operating conditions.
• The pre-injection is carried out to reduce the noise level.
• Pre-injection advance angles, the distance between pre-injection and main injection and advance angles of main
injection vary according to the instantaneous engine operating conditions.
(1) Immobilizer recognition
• When the control unit receives the signal of the key “ON” it communicates with the immobilizer control unit to en-
able starting.
(2) Checking engine coolant temperature
• The engine electronic control unit, depending on the temperature:
• Of the engine coolant, turbocharging air and fuel, operates the viscous fan and switches on the coolant temper-
ature warning light.
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(3) Checking quantity of fuel injected
• According to the signals from the sensors and the mapped values, the engine electronic control unit:
• Operates the pressure regulation valve;
• Varies the “pilot” injection time;
• Varies the “main” injection time;
• Checking idling adjustment
• The engine electronic control unit processes the signals from the various sensors and regulates the amount of
fuel injected:
• It operates the pressure regulator;
• It varies the injection times of the injectors.
(4) Checking smokiness at exhaust on acceleration
• With heavy acceleration, on the basis of the signals received from the air introduction meter and engine speed
sensor, the engine electronic control unit determines the optimum amount of fuel to inject:
• It operates the pressure regulator;
• It varies the injector injection time.
(5) Checking exhaust gas recirculation
• Depending on the engine load and the signal from the accelerator pedal sensor, the engine electronic control con-
trol unit limits the amount of air taken in, actuating partial suction of the exhaust gases.
(6) Checking engine rotation balance during acceleration
• Regular progression is assured in all conditions by the control of the pressure regulator and the injector opening
time.
(7) Glow plug control
• During:
• Preglow.
• Afterglow.
• The injection centre times the heater starter (or glow plugs for the 4P10 Engine) according to engine tempera-
ture.
(8) Checking fuel pump
• Irrespective of the speed, the engine electronic control unit:
• Supplies the auxiliary fuel pump with the key “ON”;
• Cuts off auxiliary pump supply if the engine is not started up within a few seconds.
(9) Checking fuel heater
• It times operation of fuel heater in relation to ambient temperature.
(10) Checking cylinder position
• During each turn of the engine, the engine electronic control unit recognizes which cylinder is in the power stroke
and operates the injection sequence for the appropriate cylinder.
(11) Checking pilot and main injection timing
• According to the signals from the various sensors, including the absolute pressure sensor built into the engine
electronic control unit, the engine electronic control unit determines the optimum point of injection according to in-
ternal mapping.
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(12) Checking injection pressure closed cycle
• Depending on the engine load, determined by processing the signals from the various sensors, the engine elec-
tronic control unit operates the regulator to obtain optimum line pressure.
(13) Fuel supply
• The fuel supply is calculated in relation to:
• Accelerator pedal position.
• Engine speed.
• Quantity of air introduced.
• The outcome may be corrected in relation to:
• The water temperature.
• Or to avoid:
• Noise.
• Smoke.
• Overloading.
• Overheating.
• Turbine over-revving.
• The delivery can be modified in the case of:
• Action of external devices (ABS).
• Serious trouble decreasing the load or stopping the engine.
• After determining the mass of air introduced by measuring its volume and temperature, the engine electronic con-
trol unit calculates the corresponding mass of fuel to inject into the relevant cylinder (mg per delivery) also taking
into account the temperature of the diesel.
• The mass of fuel calculated in this way is first converted into volume (mm3 per delivery) and then into degrees of
throw, or duration of injection.
(14) Correcting flow rate according to water temperature
• A cold engine meets with greater resistance during operation: friction is high, the oil is still very viscous, and the
various clearances are not yet optimized.
• In addition, the injected fuel tends to condense on the metal surfaces that are still cold.
The fuel supply for a cold engine is therefore greater than for a warm one.
(15) De-rating
• In the event of the engine overheating, injection is modified, decreasing the delivery to a varying degree, in pro-
portion to the temperature reached by the coolant.
(16) Turbine rpm setting
• Based on signals from the accelerator pedal position and intake manifold air temperature/pressure engine rpm
sensors, the electronic centre processes the field-back signal to turbo actuator pilot electro valve opening.
(17) Injection timing electronic test
• The advance (start of delivery, expressed in degrees) may be different from one injection to the next, also differen-
tiated from one cylinder to another. It is calculated, similarly to the delivery, in relation to the engine load (acceler-
ator position, engine speed and air introduced).
• The advance is appropriately corrected:
• In phases of acceleration;
• According to the water temperature.
• And also to obtain:
• Lower emissions, noise and overloading;
• Better vehicle acceleration.
• An extremely high advance is set on starting, depending on the water temperature.
• Feedback from the start of delivery is supplied by the change in impedance of the injector solenoid valve.
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(18) Speed governor
• The electronic speed governor has both features of governors:
• Idling and top speed.
• All speeds.
• It is stable in ranges where conventional, mechanical governors are imprecise.
• Within certain thresholds the speed takes account of the battery voltage.
(19) Engine starting
• During the first few turns of the engine, the timing and cylinder no. 1 recognition signals (engine speed sensor and
camshaft timing sensor) are synchronized.
• The accelerator pedal signal is ignored on starting. Starting delivery is set only according to water temperature, by
a special map.
(20) Cold starting
• If even just one of the three temperature sensors (water, air or diesel) records a temperature lower than 10°C {50
°F}, the glow plugs are activated.
• On inserting the key contact, the glow plug indicator goes on and remains on for a period varying depending on
temperature (air is heated by the pre-heating glow plugs that are located on cylinder head).
• Thereafter, the engine can be started up.
• When the motor is running this indicator light goes out, while the glow plugs continue to be powered for a certain
length of time (variable) for post-heating.
• The pre-heating curve is also variable in relation to the battery voltage.
(21) Run up
• When the key makes contact, the engine electronic control unit transfers the information stored in memory when
the engine was last stopped into the main memory (see After Run) and makes a diagnosis of the system.
(22) After run
• Whenever the engine is switched off with the key, the engine electronic control unit stays powered for about 30
seconds by the main relay.
• This makes it possible for the microprocessor to transfer some data from the main memory (volatile) to a non-vol-
atile memory, which can be erased and written over (EEPROM), so as to make it available at the next start up
(see Run Up).
• These data basically consist of:
• Various settings (engine idling adjustment, etc.);
• Settings of some components;
• Fault memory.
• The process lasts a few seconds, typically from about 30 (depending on the amount of data to save), after which
the engine electronic control unit sends a command to the main relay and makes it disconnect from the battery.
NOTE
• It is extremely important for this procedure not to be broken off, for example by switching off the engine
with the battery cut-out, or by disconnecting the battery cut-out before 20 seconds have passed since
switching off the engine. If this happens, the functioning of the system is ensured, but repeated interrup-
tions may damage the engine electronic control unit.
(23) Cut-off
• This function cuts off fuel delivery when the vehicle is decelerating (accelerator pedal released).
(24) Cylinder balancing
• Individual cylinder balancing contributes to increasing comfort and handling.
• This function permits individual, customized control over the delivery of fuel and the start of delivery for each cyl-
inder, even differently from one cylinder to another, to compensate for the hydraulic tolerances of the injector.
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• The differences in flow (delivery specifications) between the various injectors cannot be evaluated directly by the
engine electronic control unit. Therefore, it is necessary to input particular data of each injector into the engine
electronic control unit using FUSO diagnostics each time after injector replacement.
(25) Synchronisation search
• If there is no signal from the camshaft timing sensor, the engine electronic control unit is able to recognize the cyl-
inders into which the fuel is to be injected.
• If this occurs when the engine is already running, the combustion sequence has already been acquired, so the en-
gine electronic control unit continues with the sequence on which it has already been synchronized.
• If this occurs when the engine is at a standstill, the engine electronic control unit energizes a single solenoid
valve. Within 2 turns of the crankshaft, injection will take place in that cylinder, so the engine electronic control unit
just needs to get synchronized on the firing sequence and to start up the engine.
2.4 Actuators
• The injection system comprises three classes of actuators interlocked with the engine electronic control unit:
• Injectors (see relevant heading);
• Regulators (see relevant headings) requiring PWM control (Pulse Width Modulation):
• For pressure;
• EGR (Exhaust Gas Recirculation);
• Actuators with continuous ON/OFF signal to:
• Turn on/off air-conditioner compressor;
• Electric supply pump.
• Cruise control.
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2.5 Electric/electronic components
(1) Engine electrical control unit
• The engine electronic control unit is of the “flash EPROM” type, i.e. it can be reprogrammed from the outside with-
out acting on its hardware.
• The engine electronic control unit processes the signals from the sensors by applying software algorithms, and
also controls the actuators (in particular, the electric injectors and the pressure regulator).
• The engine electronic control unit records, in the memory non-labile area, the information on the engine parame-
ters originally set or acquired during engine operation.
• The injection control unit incorporates the atmospheric sensor, in order to further improve the injection system
control.
• The engine electronic control unit is fitted to the left side of the engine compartment and is connected to the vehi-
cle wiring by means of two connectors:
• 60-pole connector “Engine side injection cable connector” for the components available on the engine;
• 94-pole connector “Bonnet/cab cable connector” for the components on the vehicle.
• In addition to controlling the system functions described in the respective charter, the engine electronic control
unit is interfaced with the other electronic systems found on the vehicle, such as ABS (Anti-lock Brake System),
speed limiter, EGR (Exhaust Gas Recirculation), preheating plugs.
• On the vehicles equipped with DPF (Diesel Particulate Filter), the engine electronic control unit also controls the
DPF regeneration system. In this case, after any of the operations below is carried out:
• Replacing one or several injectors,
• Replacing all the injectors,
The engine electronic control unit shall be programmed again by means of the FUSO Diagnostics, and the re-
placement procedure for the concerned component shall be performed, in accordance with the indications of the
diagnosis instruments.
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(2) FMU (fuel metering unit)
• The FMU (fuel metering unit) is mounted on the low-pressure circuit of the high pressure pump. The pressure reg-
ulator modulates the amount of fuel sent to the high-pressure circuit according to the commands received directly
from the engine electronic control unit. The pressure regulator is mainly composed of the following components:
• Connector.
• Casing.
• Solenoid.
• Pre-load spring.
• Hutter cylinder.
• When there is no signal, the pressure regulator is normally open, therefore with the pump providing maximum de-
livery.
• The engine electronic control unit, via the PWM (Pulse Width Modulation) signal, modulates the change in fuel
flow rate in the high-pressure circuit by partially closing or opening the sections of passage of the fuel in the low-
pressure circuit.
(2.1) Operation
• When the engine electronic control
unit governs the FMU (fuel metering
unit) (via PWM signal), the solenoid is
energized that, in its turn, generates
the movement of the magnetic core.
The shift of the core causes the shut-
ter cylinder to move axially, reducing
the flow of fuel.
• When the solenoid is not energized,
the magnetic core is pushed into the
rest position by the pre-load spring. In
this condition, the shutter cylinder is in
such a position as to offer the fuel the
maximum flow and pressure.
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(3) Injector
• When the piezoelectric actuator is
reached by an electrical load, com-
manded by the engine electronic con-
trol unit, it increases its length. The
movement, amplified by the hydraulic
amplifier, act mechanically on the con-
trol valve and it allows therefore the in-
jection of the fuel present in the high
pressure line. While stopping the elec-
trical load, the actuator reacts elasti-
cally and again assumes its initial
length.The springs add their contribu-
tion, winning the pressures that act in
balancing on the whole surface of the
components. The fuel in excess is
than recirculated in the fuel circuit
through the connection for fuel return
flow.
(4) Engine speed sensor
• It is an inductive sensor and is posi-
tioned on the phonic wheel fitted on
the front end of the drive shaft.
• It generates the signals resulting from
the magnetic flow lines which close
through the teeth of the phonic wheel.
• The engine electronic control unit uses
this signal to measure the speed of ro-
tation of the engine, its angular posi-
tion and to operate the electronic RPM
counter.
• If this signal fails the RPM counter will
not work.
• The sensor gap shall be as follows:
• 1 ± 0.5 mm {0.039 ± 0.020 in.}, be-
tween distributing shaft pulley and
phase sensor,
• 1 mm {0.039 in.}, between phonic
wheel and engine speed sensor.
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(5) Camshaft timing sensor
• It is an inductive sensor and is posi-
tioned on the camshaft gear of the
suction valves.
• It generates the signals resulting from
the magnetic flow lines which close
through a slot on the gear itself.
• The signal generated by this sensor is
used by the engine electronic control
unit as a redundant signal to measure
the different engine speeds.
(6) Boost pressure and temperature
sensor
• Positioned on the intake manifold, it
measures the pressure of the turbo-
charging air introduced into the intake
manifold.
• This value, together with that of the
boost pressure and temperature sen-
sor, makes it possible for the engine
electronic control unit to calculate the
exact quantity of air introduced into the
cylinders so as to operate the injectors
adjusting the fuel delivery, limiting
harmful emissions, improving con-
sumption and performance.
• The sensor contains an electronic
temperature correction circuit to opti-
mize the pressure measurement in re-
lation to the temperature of the intake
air.
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(7) Water temperature sensor
• When temperature sensor for engine
control provides the engine electronic
control unit with an index of the ther-
mal status of the engine in order to de-
termine corrections for the fuel
delivery, injection pressure, exhaust
gas recirculation injection advance
when starting cold (if mounted) and
warm-up.
(8) Atmospheric pressure sensor
• This is integrated in the engine electronic control unit. It provides a criterion of correction for the measurement of
the air flow rate and to calculate the reference air flow rate to check the EGR.
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(9) Glow plug electronic control unit
1 Connections glow plugs
2 Connections glow plugs
3 Connections glow plugs
4 Connections glow plugs
6 Ground
7 Start switch (+15)
10 Battery positive (+30)
2 3
11 Input: control signal from
1 4
7 engine electronic control unit
6
10 11
• The glow electronic control unit is controlled by engine electronic control unit and has following functions:
• Switch of 4 glow plugs, control signal from engine electronic control unit;
• Reversible overcurrent cut-off (electronic safety fuse);
• Recognition of one or several damaged glow plugs and overall defect diagnosis;
• High voltage switch - off by engine electronic control unit;
(10) Glow plug
[CONTROL VALUES]
• With a constant supply voltage of 11 V:
• Max. current drawn: 18 A.
• In 5 sec: 11 ± 1.5 A.
• In 30 sec: 6 ± 0.9 A.
• Temperature after 7 sec.: 850°C.
{1562°F}
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M E M O
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2.6 Electronic control unit connection diagram
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