Operation In Acceleration Conditions; Operation In Deceleration Conditions; Operation In Cut-Off Conditions - Fiat Bravo/Brava Workshop Manual

Bravo- Brava W
16v
1999 update
Engine
Fuel system
10.
Operation in acceleration conditions
During this stage, the control unit increases the quantity of fuel supplied.
The "basic" injection time is multiplied by a coefficient which depends on the temperature of the engine
and the opening speed of the accelerator butterfly (average value 1.2).
If the sharp variation in the injection time is calculated when the injector is already closed, the control unit
reopens the injector (extra pulse) in order to compensate the mixture strength as quickly as possible: the
subsequent injections are, on the other hand, already increased on the basis of the coefficients mentioned
previously.
A: normal injection time
B: injector reopening (extra-pulse)
C: injection time inculding enrichment
OFF: engine at stationary speed
ON: engine in transition
Operation in deceleration conditions
During this stage a negative transition strategy is implemented to decrease the quantity of fuel supplied:
the "basic" injection time is multipled by a coefficient which depends on the temperature of the engine
and the engine speed and load conditions in the moment immediately preceding the start of deceleration.
Operation in cut-off conditions
The cut-off strategy is implemented when the control unit recognizes that the butterfly is in the idle posi­
tion (signal from the butterfly potentiometer) and the engine speed is above 1600 rpm (with the engine
warm).
The supply to the engne is re-enabled when the butterfly is in a not closed position or when the engine
speed goes below 1200 rpm (with the engine warm).
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