Fiat 1996 Brava Service Manual page 417

Bravo-Brava @» i* Engine
'98 range Fuel system
10.
Self-adaptivity
The control unit has a strength self-adaptivity function, which memorizes any deviations between basic
mapping and corrections imposed by the Lambda probe which may arise peristently during operation.
These deviations (due to ageing of the components of the system and engine) are memorized perma­
nently, allowing the operation of the system to adapt to the gradual alterations of the engine and com­
ponents in relation to the characteristics when new. To delete the corrections memorized, use the appro­
priate function on the diagnistic equipment. The corrections are NOT lost even if the battery or control
unit are disconnected.
The strategy is disabled during the period when the fuel vapour cut-off solenoid is open. If the control
unit is replaced, it is advisable to run the engine at idle speed for a few minutes (hot engine) to allow the
control unit to re-memorize the corrections. Corrections at speeds higher than idle speed are memorized
during normal driving conditions.
The control unit also has a self-adaptivity function which corrects the opening of the idle speed actuator
at idle speed on the basis of variations due to leaks from the throttle body or natural ageing of the en­
gine. This specific correction is lost if the battery or control unit are disconnected.
Starting and post-starting
During starting, it is not possible to recognize instantaneously the engine timing, and so it is not possible
to effect phased fuel injection for the first injection of each cylinder.
During the first few engine revolutions, a first simultaneous injection (full group) is effected because
significant fluctuations in engine speed do not permit correct calculation of the injection timing; only af­
ter does injection become phased.
The "basic" injection time is increased by a multiplicative coefficient for as long as the engine is driven
by the starter motor.
After starting, the coefficient is gradually reduced until it disappears within^ a particular time period
which is all the longer the lower the engine temperature. /
k: enrichment coefficient
t : time
a : decrease in relation to engine
temperature
ON: engine driven (crank)
OFF: engine started (run)
k'
k
ON
ar^
OFF
t
P4A06IJ01
Copyright Fiat Auto 5