Iveco daily euro 4, Repair Manual

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84
ELECTRIC/ELECTRONIC SYSTEM D
AILY
E
URO
4
Base - March 2006 Print 603.93.651
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.
Turbine rpm setting
(for the variable geometry turbo-compressor)
By changing its geometry, adjusted turbine speed is
monitored by the electronic centre via an electrical signal
feeding the compressed air actuator electro valve. Based on
signals from the accelerator pedal position and suction
manifold air temperature/pressure engine rpm sensors, the
electronic centre processes the field-back signal to properly
modulate turbine actuator pilot electro valve opening.
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.
Cold starting
If even just one of the three temperature sensors (water, air
or diesel) records a temperature lower than 10
°
C, pre-post
heating is activated.
On inserting the key contact, the pre-heating 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 for F1 engines), then it blinks.
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.
If, with the indicator light flashing, the engine is not started
up within 20-25 seconds (inattention time), the operation is
cancelled so as not to run down the batteries pointlessly.
The pre-heating curve is also variable in relation to the
battery voltage.
Warm starting
If the reference temperatures all exceed 10
°
C, when the key
makes contact the indicator light comes on for
approximately 2 sec., for a short test, and then goes out. It
is now possible to start up the engine.
Run up
When the key makes contact, the 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.
After run
Whenever the engine is switched off with the key, the
control unit stays powered for a few seconds by the main
relay.
This makes it possible for the microprocessor to transfer
some data from the main memory (volatile) to a non-volatile
memory, which can be erased and written over (EEPROM),
so as to make it available at the next start up (see Run Up).