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ECU
The ECU (1) is situated under the tank behind the bat-
tery.
The ECU consists of a CPU (Central Processing Unit),
a memory unit and I/O sections (input/output).
The signal of each individual sensor is sent to the input
section and then to the CPU. On the basis of the sig-
nals received, the ECU calculates the volume of fuel
and the ignition advance necessary by utilising pre-
pared schemes for the various conditions of the engine
and sending them respectively to the injectors and the
ignition coils.
D
SENSORS
ATMOSPHERIC AIR TEMPERATURE SENSOR
The suction air sensor (1) is on the front of the filter box
cover and provides the value of the air temperature.
Check
Connect the connector and measure the resistance
value between the two contacts on the sensor, which
must be 2.5 kOhm ±10% at 20°C.
1 INTAKE AIR PRESSURE SENSOR
The sensor (2) reveals the pressure of the intake air
and this pressure is therefore converted into voltage
that is sent to the ECU.
The signal involved has a double purpose, one
being that of phasing the injection and ignition of the
cylinders and the second being that of adjusting the
base fuel injection time (volume); this is in fact
determined depending on the tension of the signal
(output tension).
The voltage increases when the pressure of the
intake air is high.
The sensor is checked by diagnostic software.
Output voltage
(V)
Low
Air intake injection system
Pressure of the
intake air (mmHg)
High
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1
2
1
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