Fiat 1995 Brava, Руководство по обслуживанию

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Bravo ft
20v
E n g i n e
Fuel system
1 0 .
T I M I N G S E N S O R (0.232.101.036)
The Bosch Motronic M 2.10.4 system uses a
sequential timed system, i.e. the injection of
the fuel takes place in sequence for each
cylinder during the inlet stroke.
To achieve this, the electronic control unit al-
so uses a timing signal to determine the in-
jection point in addition to the rpm and T D C
signal.
The signal sent to the control unit is pro-
duced by a Hall effect sensor fitted by the
camshaft drive pulley, exhaust side.
Operating principle
P4A21FJ01
A semi-conductor layer with current passing through, immersed
in a normal magnetic field (lines of force perpendicular to the di-
rection of the current) generates a difference in power, known as
"HALL" tension.
If the intensity of the current remains constant, the tension gen-
erated depends only on the intensity of the magnetic field; it is
therefore sufficient for the intensity of the magnetic field to be
varied periodically to obtain a modulated electrical signal where
the frequency is proportional to the speed with which the mag-
netic field changes.
To obtain this change, a metal ring (inner part of the pulley) with
an opening is made to pass through the sensor. When it moves
the metal part of the ring covers the sensor blocking the magnetic
field with the consequent low output signal; viceversa, by the
opening and therefore where the magnetic field is present, the
sensor generates a high signal.
As a result the high signal alternates with the low signal once every two revolutions of the engine and
precisely when cylinder N°1 is 78° before T D C .
This signal, together with the rpm and T D C signal, allows the control unit to recognize the cylinders and
determine the injection point. For each revolution of the engine the control unit checks that the timing
signal is present; if this signal is lacking for two consecutive revolutions, the control unit signals the fail-
ure (warning light in the instrument panel comes on) and the engine cannot be started up.
1. Deflector (pulley seal)
2. Magnetic material
Wiring connector
The numbers indicate the corresonding pins
for the control unit
Removing-refitting
This operation involves removing the timing
belt and the camshaft pulley, exhaust side.
When these operations have been carried out
it is necessary to:
- disconnect the electrical connector;
- Undo the fixing bolts and remove the sen-
sor.
When refitting carry out the procedure in the
reverse order, following the instructions for
fitting and tensioning the toothed belt.
NOTE The sensor does not require any
type of adjustment.
Copyright by Fiat Auto
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