The Multipoint Fuel Injection System consists of
sensors which detect the engine conditions, the
engine-ECU <M/T> or engine-A/T-ECU <A/T> which
controls the system based on signals from these
sensors, and actuators which operate under the
control of the engine-ECU <M/T> or engine-A/T-ECU
<A/T>. The engine-ECU <M/T> or engine-A/T-ECU

<A/T> carries out activities such as fuel injection
control, idle speed control and ignition timing control.
In addition, the engine-ECU <M/T> or
engine-A/T-ECU <A/T> is equipped with several
diagnosis modes which simplify troubleshooting
when a problem develops.

FUEL INJECTION CONTROL

The injector drive times and injection timing are
controlled so that the optimum air/fuel mixture is
supplied to the engine to correspond to the
continually-changing engine operation conditions.
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 being
regulated by the fuel pressure regulator. The fuel
thus regulated 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 1-3-4-2. This is called sequential fuel
injection. The engine-ECU <M/T> or
engine-A/T-ECU <A/T> provides a richer air/fuel

mixture by carrying out "open-loop" control when the
engine is cold or operating under high load
conditions in order to maintain engine performance.
In addition, when the engine is warm or operating
under normal conditions, the engine-ECU <M/T> or
engine-A/T-ECU <A/T> controls the air/fuel mixture
by using the oxygen sensor signal to carry out
"closed-loop" control in order to obtain the theoretical
air/fuel mixture ratio that provides the maximum
cleaning performance from the three way catalyst.

THROTTLE VALVE OPENING CONTROL

This system electrically controls the opening of the
throttle valve. The engine-ECU <M/T> or
engine-A/T-ECU <A/T> detects the amount of travel
of the accelerator pedal via the accelerator pedal
position sensor, and controls the actuation of the
throttle valve control servo, which is mounted on the
throttle body, in order to attain the target throttle
valve opening that has been predetermined in
accordance with driving conditions.

IDLE AIR CONTROL

The idle speed is kept at the optimum speed by
controlling the amount of air that passes through the
throttle valve in accordance with changes in idling
conditions and engine load during idling.
The engine-ECU <M/T> or engine-A/T-ECU <A/T>
drives the throttle valve control servo to keep the
engine running at the pre-set idle target speed in
accordance with the engine coolant temperature and
A/C and other electrical load. In addition, when the

air conditioning switch is turned off and on while the
engine is idling, the throttle valve control servo
adjusts the throttle valve passes through air amount
according to the engine load conditions to avoid
fluctuations in the engine speed.

IGNITION TIMING CONTROL

The power transistor located in the ignition primary
circuit turns ON and OFF to control the primary
current flow to the ignition coil. 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
engine-ECU <M/T> or engine-A/T-ECU <A/T> from
the engine speed, intake air volume, engine coolant
temperature and atmospheric pressure.

GENERAL INFORMATION

MULTIPORT FUEL INJECTION (MPI)

13A-5

SELF-DIAGNOSIS FUNCTION

• When an abnormality is detected in one of the

sensors or actuators related to emission control,
the engine warning lamp (check engine lamp)
illuminates as a warning to the driver.

• When an abnormality is detected in one of the

sensors or actuators, a diagnosis code
corresponding to the abnormality is output.

• The RAM data inside the engine-ECU <M/T> or

engine-A/T-ECU <A/T> that is related to the
sensors and actuators can be read by means of
the MUT-III. In addition, the actuators can be
force-driven under certain circumstances.

OTHER CONTROL FUNCTIONS

1. Fuel Pump Control

Turns the fuel pump relay ON so that current is

supplied to the fuel pump while the engine is
cranking or running.

2. A/C Relay Control

Turns the compressor clutch of the A/C ON and OFF.

3. Oil Control Valve Control

The engine-ECU <M/T> or engine-A/T-ECU <A/T>

effects duty cycle control on the engine oil control
valve, in accordance with the engine speed. This
regulates the supply of engine oil to the intake
rocker shaft, which switches the cams.

4. Fan Motor Control

The revolutions of the radiator fan and condenser fan

are controlled in response to the engine coolant
temperature and vehicle speed.

5. Alternator Output Current Control

Prevents alternator output current from increasing

suddenly and idle speed from dropping at times
such as when the headlamp are turned on.

6. Purge Control Solenoid Valve Control

(Refer to

P.17-61

, GROUP 17

− Engine And

Emission Control

− Evaporative Emission Control

System).

7. EGR Control Solenoid Valve Control

[Refer to

P.17-64

, GROUP 17

− Engine And

Emission Control

− Exhaust Gas Recirculation

(EGR) System].

GENERAL SPECIFICATIONS

Items

Specifications

Throttle body

Throttle bore mm

Throttle position sensor

Hall element type

Throttle valve control servo

DC motor type, having broshes

engine-ECU
<M/T>

Identification No.

E6T41876

Engine-A/T-E
CU <A/T>

Identification No.

E6T41875

Sensors

Air flow sensor

Heat sensitizing type

Barometric pressure Sensor

Semiconductor type

Intake air temperature sensor

Thermistor type

Engine coolant temperature sensor

Thermistor type

Oxygen sensor

Zirconia type

Accelerator pedal position sensor

Hall element type

Vehicle speed sensor <M/T>

Magnetic resistive element type

Inhibitor switch <A/T>

Contact switch type

Camshaft position sensor

Magneto resistance element type

Crank angle sensor

Magneto resistance element type

Detonation sensor

Piezoelectric type

Power steering fluid pressure sensor

Semiconductor type

GENERAL INFORMATION

MULTIPORT FUEL INJECTION (MPI)

13A-6

Actuators

Engine control relay type

Contact switch type

Fuel pump relay type

Contact switch type

Injector type and number

Electromagnetic type, 4

Injector identification mark

HDA305E

Throttle actuator control motor relay

Contact switch type

Oil control valve

Duty cycle type solenoid valve

EGR valve

Stepper motor

Purge control solenoid valve

Duty cycle type solenoid valve

Fuel pressure
regulator

Regulator pressure kPa

328

Items

Specifications

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