Mitsubishi Eclipse 1990, Service Manual

Page: 518 / 2103

ENGINE
AND ENGINE> G e n e r a l
ENGINE (TURBO) AND ENGINE>
13199910319
GENERAL INFORMATION
The Fuel Injection System consists
of sensors which detect the engine conditions,
the ENGINE CONTROL MODULE (ECM) which
controls the system based on signals from these
sensors, and actuators which operate under
the control of the ECM.
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 regula-
tor. 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
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 id-
ling.
The ECM drives the idle air control (IAC) motor
to keep the engine running at the pre-set idle
target speed in accordance with the engine
IGNITION TIMING CONTROL
The ignition power transistor located in the igni-
tion primary circuit turns ON and OFF to control
the primary current flow to the ignition coil.
This controls the ignition timing in order to pro-
vide the optimum ignition timing with respect
The ECM carries out activities such as fuel
injection control, idle air control and ignition
timing control.
In addition, the ECM is equipped with several
diagnostic test modes which simplify trouble-
shooting when a problem develops.
. .
crankshaft. The firing is This
is called The provides a richer
air/fuel mixture by carrying out “open-loop” con-
trol when the engine is cold or operating under
high load
in order to maintain engine
performance.
In addition, when the engine is warm or operat-
ing under normal conditions, the ECM 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 per-
formance from the three way catalyst.
coolant temperature and air conditioning load.
In addition, when the air’ conditioning switch
is turned off and on while the
is
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.
to the engine operating conditions. The ignition
timing is determined by the ECM from the en-
gine speed, intake air volume, engine coolant
temperature and atmospheric pressure.
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