Fiat 1995 Brava, Service Manual

Page: 216 / 544

Engine
Bravo-Brava
Fuel system
10.
INJECTION MANAGEMENT
The injection management strategies have the aim of supplying the engine with the correct quantity of
fuel at the desired moment according to the engine operating conditions.
NOTE The presence of the air flow meter makes it possible to directly measure the mass of intake air,
making the presence of the intake air temperature sensor superfluous.
The management of the injection consists essentially in the calculation of the injection time, the deter-
mining of the injection timing and the subsequent implementation by operaating the injector.
The "basic" injection time depends on the characteristics of the injector and corresponds to the quantity
of fuel to be injected into each cylinder. The latter, in turn, multiplies the quantity of air drawn in by each
cylinder (calculated on the basis of the quantity of intake air and on the engine rotation speed) for the
desired mixture strength in relation to the engine operating point.
The final injection time is determined through a calculation algorhythm in which the "basic" injection
time is corrected by a series of coefficients which take into account the different engine operating condi-
tions which are shown by the various sensors present in the system.
A: "basic" injection time
B: corrective coefficients: low engine temperature
high engine temperature
starting and post-starting
butterfly fully open
deceleration
acceleration
C: checking mixture strength
D: self-adjustment
E: cut-off
F: intermediate injection time
G: extra-pulse
H: management not timed by injection
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Print no. 506.670