Mitsubishi Eclipse 1990 Service Manual page 383

ENGINE (NON-TURBO)>
GENERAL INFORMATION
The Fuel Injection System consists
of sensors which detect the engine conditions,
the POWERTRAIN CONTROL MODULE
(PCM) which controls the system based on
signals from these sensors, and actuators
which operate under the control of the PCM.
FUEL INJECTION CONTROL
The injector drive times and injector timing are
controlled so that the optimum air/fuel mixture
is supplied to the engine to correspond to the
continually-changing engine operation condi-
tions.
A single injector is mounted at the intake port
of each cylinder. Fuel is sent under pressure
from the fuel tank by the fuel pump, with the
pressure regulated by the fuel pressure
regulator. The regulated fuel is distributed
to each of the injectors.
Fuel injection is normally carried out once for
each cylinder for every two rotations of the
crankshaft. The firing order is
IDLE AIR CONTROL
The idle speed' is kept at the optimum speed
by controlling the amount of air that bypasses
the throttle valve in accordance with changes
in idling conditions and engine load during
idling.
The PCM drives the idle air control (IAC) motor
to keep the engine running at the
target speed in accordance with the engine
IGNITION TIMING CONTROL
The ignition power transistor is built into the
PCM. It turns the ignition primary circuit on
and off to respectively supply and cut off primary
current flow to the ignition coil.
ENGINE (NON-TURBO)>
FUEL INJECTION
This
idle
TSB Revision
General
The PCM carries
injection control, idle air control and ignition
timing control.
In addition, the
diagnostic
t e s t
troubleshooting when a problem develops.
is called The PCM
air/fuel mixture by carrying out "open-loop"
control when the engine is cold or operating
under high load conditions in
engine performance.
In addition, when the engine
operating under normal
controls the air/fuel mixture by using the heated
oxygen sensor signal to carry out "closed-loop"
control in order to obtain the theoretical air/fuel
mixture ratio that provides the maximum
cleaning
catalyst.
coolant temperature and air conditioning load.
In addition, when the air conditioning switch
is turned off and on while the engine is idling,
the motor operates to adjust the throttle
valve bypass air amount in accordance with
the engine load conditions in order to avoid
fluctuations in the engine speed.
This controls the ignition timing in order to
provide the optimum ignition timing with respect
to the engine operating conditions. The ignition
timing is determined by the PCM from the
engine speed, intake air volume, engine coolant
temperature and atmospheric pressure.
activities such fuel
which simplify
to maintain
warm or
the PCM
from the three way