Hyundai Sonata 1991 Shop Manual page 244

MPI SYSTEM
o Air-fuel ratio map correction (Open loop control correction)
Correction to the optimum air/fuel ratio is made by the map
values set by engine speed and amount of intake air.
o Engine coolant temperature correction
To maintain driveability of a cold engine, correction is made
to increase the amount of intake air relative to the
temperature of the coolant.
o Intake air temperature correction
Change in air/fuel ratio due to difference in intake air density
caused by intake air temperature is corrected.
o Atmospheric pressure correction
Change in air/fuel ratio due to difference in intake air
density caused by change in atmospheric pressure is
corrected.
o Acceleration/deceleration correction
In accordance with the change in the amount of intake air,
fuel amount is corrected, improving driveability on accel-
eration and deceleration.
o Dead time correction
The injectors opened by the driving signal from ECU have
operational lag which changes according to difference due
to battery voltage. This means that actual injector valve open-
ing time becomes less than injector driving signal, failing to
provide expected air/fuel ratio.
Therefore, battery correction time corresponding to the bat-
tery voltage is added.
ON
Drive OFF Dead I Valve open time
signal time
I
:::d
I----L
Injector-----
I Valve open t;me
I
1
4
"'1
31YOO8
Time
(ms)
L -_ _
-,_-'-_-=_IV)
Battery
31YOO9
31-19