Learning Control System - Subaru SVX 1992 Manual

FUEL INJECTION SYSTEM
[M603) 2-7
4) Learning control system
In a conventional air-fuel feedback control system, the
basic amount of fuel injected (according to engine
speed and various loads) is stored in the memory . After
the ECU receives a signal emitted from the OZ sensor,
the basic amount of fuel injected is corrected so that it is
close to the theoretical air-fuel ratio. This means that the
greater the air-fuel ratio is corrected, the lesser the
control accuracy .
Cam angle sensor
Crank angle sensor 1
Crank angle sensor 2
Air flow sensor
In Subaru engines, however, an air-fuel ratio learning
control system constantly memorizes the amount of
correction required in relation to the basic amount of
fuel to be injected (the basic amount of fuel injected is
determined after several cycles of fuel injection), so that
the correction affected by feedback control is mini-
mized. Thus, quick response and accurate control of
variations in air-fuel ratio, sensors' and actuators' char-
acteristics during operation, as well as in the air-fuel
ratio with the time of engine operation, are achieved . In
addition, accurate control contributes much to stability
of exhaust gases and driving performance .
Water temperature sensor
i --W- I
ECU i 1 1 Injector
17
Inhibitor switch