Iveco daily euro 4, Repair Manual

Page: 324 / 1132

Checking diesel warming
It times operation of diesel warming in relation to ambient
temperature.
Checking cylinder position
During each turn of the engine, the control unit recognizes
which cylinder is in the power stroke and operates the
injection sequence for the appropriate cylinder.
Checking pilot and main injection timing
According to the signals from the various sensors, including the
absolute pressure sensor built into the control unit, the control
unit determines the optimum point of injection according to
internal mapping.
Checking injection pressure closed cycle
Depending on the engine load, determined by processing the
signals from the various sensors, the control unit operates the
regulator to obtain optimum line pressure.
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), ABD, EDB
- serious trouble decreasing the load or stopping the engine.
After determining the mass of air introduced by measuring its
volume and temperature, the control 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 (mm
3
per delivery) and then into degrees of throw,
or duration of injection.
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.
Correcting flow rate to avoid noise, smoke or
overloading
The behaviour that could lead to this kind of trouble is well
known.
The designer has therefore included special instructions in the
control unit to avoid it.
De-rating
In the event of the engine overheating, injection is modified,
decreasing the delivery to a varying degree, in proportion to
the temperature reached by the coolant.
Injection timing electronic test
The advance (start of delivery, expressed in degrees) may be
different from one injection to the next, also differentiated
from one cylinder to another. It is calculated, similarly to the
delivery, in relation to the engine load (accelerator 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.
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.
Engine starting
During the first few turns of the engine, the timing and cylinder
no. 1 recognition signals (flywheel sensor and camshaft sensor)
are synchronized.
The accelerator pedal signal is ignored on starting. Starting
delivery is set only according to water temperature, by a
special map.
When the control unit detects such speed and acceleration of
the flywheel as to be able to consider the engine started up
and no longer driven by the starter motor, it re-enables the
accelerator pedal.
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F1C ENGINE D
AILY
E
URO
4
Base - March 2006 Print 603.93.651