Chrysler laser 1990 Technical Information Manual page 153

During normal operation (including idling), the en-
gine control unit controls the injector activation time
ter, on the basis of the oxygen sensor signal.
When the air/fuel mixture is richer than the
stoichiometric ratio, there is less oxygen in the
exhaust gas and thus the oxygen sensor output
voltage is higher; hence a "mixture rich" signal is
input to the engine control unit. Then, the engine
control unit decreases the amount of fuel injected. If
the air/fuel ratio decreases to the point that and the
mixture becomes leaner than the stoichiometric
ratio, the oxygen concentration in the exhaust gas
increases and the oxygen sensor output voltage
becomes lower. Then, a "mixture lean" signal is
Engine speed rpm
I
Coolant temperature "C ("Fj
Intake air temperature "C ("F)
FUEL SYSTEM -
OPEN LOOP CONTROL
I
The amount of fuel injected is controlled according to the map
value* preset for each engine speed and A/N (refer to P.l4-39
FOR YOUR INFORMATION).
*Map value: Value preset and stored in the ROM of the engine
control unit.
ENRICHMENT
When the throttle valve is wide open, control is performed to
increase the amount of fuel injected, in order to secure good
driveability under high load conditions.
FUEL INJECTION CONTROL DURING ENGINE WARM-UP
I
To secure good driveability when the engine is still cold, control
is performed to increase the amount of fuel injected when the
engine cooiant temperature is low.
FUEL INJECTION CONTROL ACCORDING TO INTAKE AIR
TEMPERATURE
Given a constant intake air volume, the change in intake air
temperature alters the intake air density, resulting in an
improper air-fuel ratio.
To correct this deviation, the amount of fuel injected is
controlled; i.e., the amount of fuel injected is increased to
compensate for the higher intake air density caused by the
decreased intake air temperature.
input to the engine control unit.
Upon input of this signal, the engine control unit
increases the feedback correction factor, thus caus-
ing more fuel to be injected.
By means of the above-mentioned controls (collec-
tively called "feedback control"), the air-fuel mixture
is maintained at the stoichiometric ratio.
Under the following specific conditions, this feed-
back control is not performed, in order to improve
d r i v e a b i l i t y .
While cranking the engine
During engine warm-up when engine coolant
temperature is less than 45°C (113°F)
During acceleration/deceleration
During high load operation
When oxygen sensor is not functioning
14-41