Fiat Bravo Service Manual page 181

Engine
Fuel system
10.
34
Bravo-Brava 1 0
INTAKE AIR TEMPERATURE
SOR (Jaeger ATS-04)
The sensor is installed on the inlet port.
It consists of a brass body, from which a plastic
cage emerges. This protects the actual resistive ele-
ment, which is an NTC ("Negative Temperature C o -
efficient") thermistor; the electrical resistance of the
sensor decreases as the temperature increases.
Depending on the temperature of the air drawn in
by the manifold, the NTC thermistor varies its resis-
tance in accordance with the diagram in the figure.
The reference voltage for the air sensor is 5V; as this
circuit is designed as a voltage divider, this voltage
is shared between a resistor present in the electronic
control unit and the air sensor's N.T.C. resistor. The
electronic control unit is thus able to assess the
variations in the sensor's resistance via changes in
the voltage, and thus obtain infromation concern-
ing the intake air temperature.
Together with the absolute pressure information,
this information is used by the electronic control
unit to establish the "AIR DENSITY" which is es-
sential information for ascertaining the quantity of
air drawn in by the engine, in accordance with
which the computer will have to work out the injec-
tion time, i.e. the exact quantity of petrol to be deliv-
ered.
Checking resistance
The diagram shows the trend of the sensor's charac-
teristic curve, which can be measured by disconnect-
ing the connector and connecting an ohmmeter to the
sensor's terminals.
Removing-refitting
Disconnect the electrical connection and remove
the sensor screwed in the inlet port.
Tightening torque: 2.4 daNm
Recovery
An air T = 54°C is assumed.
Self-adaptivity during idling is inhibited.
Wiring connector
The numbers in squares indicate the corresponding
control unit pins.
16v
SEN-
Publication no. 506.670/07