Fiat 1995 Brava, Service Manual

Page: 379 / 544

E n g i n e
Fuel system
1 0 .
Bravo ft
20v
B U T T E R F L Y V A L V E P O S I T I O N S E N -
SOR (0.280.122.001)
The sensor is made up of a potentiometer in-
serted in a plastic container which has two
fins, in which there are two openings WITH-
OUT S L O T S which have the function of en-
suring the anchorage and the positionining
of the sensor in relation to the butterfly valve.
A three pin socket in the container guaran-
tees the electrical connection with the elec-
tronic control unit.
During operation, the injection/ignition con-
trol unit provides the potentiometer with a
supply of 5 Volts at pins (1) and (2).
There is a voltage at pin 3 which is inversely
proportional to the opening position of the
butterfly valve. According to the voltage sent
by pin 3 the control unit recognizes the open-
ing condition for the butterfly valve and suit-
ably corrects the mixture strength.
With the butterfly closed an elecrical voltage
signal of around 0.5 Volts reaches the control
unit which recognizes the idle and cut off
conditions (distinguishing them on the basis
of the engine speed).
The potentiometer automatically recognizes
the butterfly idle position by means of a "self-
Recovery -adjustment" function. This eliminates the
, , ., . , ,. , adjustment operations and makes it possible
If the sensor fails, the control unit establishes
t 0 a |
,
o w f o r a n y w e a r w h i c h m a y o c c u r f o r
the following parameters:
t h e b u t t e r f
|
y d o s u r e
position.
Butterfly opening angle = 10°
idle state: air flow rate < 12.8 m3/h;
exit from idle state: air flow rate > 8 m3/h;
full load state: engine load > 6,5 ms and simultaneous speed > 2000 RPM;
exit from full load state: engine load < 6,5 ms or speed < 2000 R P M .
Additional provisions
The engine idle speed gradual decrease (dashpot) and idle self-adjustment strategies are stopped.
Wiring connector
P 4 A 2 8 F J 0 2
NOTE The numbers indicate the corresponding control unit pins
28
Print no. 506.670