GENERAL INFORMATION

The Multipoint Fuel Injection System consists of sensors which detect the engine conditions, the engine-ECU which controls the system based on signals from these sensors, and actuators which operate under the control of the engine-ECU. The engine-ECU carries out activities such as fuel injection control, idle speed control and ignition timing control. In addition, the engine-ECU 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 1-3-2. This is called sequential fuel injection. The engine-ECU 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 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 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 SPEED 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 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 from the engine speed, intake air volume, engine coolant temperature and atmospheric pressure.

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 that is related to the sensors and actuators can be read by means of the M.U.T.-III. In addition, the actuators can be force-driven under certain circumstances.

OTHER CONTROL FUNCTIONS

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.
A/C Compressor Relay Control
Actuated the A/C compressor relay in accordance with the signals provided by the A/C-ECU via Controller Area Network (CAN) communication.
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.
Purge Control Solenoid Valve Control
(Refer to , GROUP 17 - Engine And Emission Control - Evaporative Emission Control System).
Auto Stop & Go (AS&G) System Control <Vehicles with AS&G system>
To reduce CO2 emitted from the vehicle, the engine-ECU monitors the operational status of the vehicle through the various sensors. If the specified conditions are satisfied, the engine-ECU stops the engine. (auto stop) When the driver depresses the clutch pedal, the engine-ECU starts the engine again. (auto start)

GENERAL SPECIFICATIONS

Items		Specifications
Throttle body	Throttle bore mm	40
	Throttle position sensor	Hall element type
	Throttle valve control servo	DC motor type, having brushes
Engine-ECU	Identification No.	E6T73476H <134> E6T73487H <3A9-vehicles without AS&G system> E6T73488H <3A9-vehicles with AS&G system>
Sensors	Intake air temperature sensor	Thermistor type
	Engine coolant temperature sensor	Thermistor type
	Oxygen sensor	Zirconia type
	Accelerator pedal position sensor	Variable resistor type
	Camshaft position sensor	Magneto resistance element type
	Crank angle sensor	Magneto resistance element type
	Detonation sensor	Piezoelectric semiconductor type
	Manifold absolute pressure sensor	Semiconductor type
	Neutral position sensor <Vehicles with AS&G system>	Detection by positional relation between linear primary coil and permanent magnet on it
	Battery current sensor <Vehicles with AS&G system>	Hall element type
	Battery temperature sensor <Vehicles with AS&G system>	Thermistor type
	Brake vacuum sensor <Vehicles with AS&G system>	Piezo resistive semiconductor
	Auto Stop & Go (AS&G) OFF switch <Vehicles with AS&G system>	Contact switch type
	Clutch switch (A) <Vehicles with AS&G system>	Contact switch type
	Clutch switch (B) <Vehicles with AS&G system>	Contact switch type
	Hood buzzer switch <Vehicles with AS&G system>	Contact switch type
Actuators	Engine control relay	Contact switch type
	Fuel pump relay	Contact switch type
	Throttle valve control servo relay	Contact switch type
	Purge control solenoid valve	Duty cycle type
	Injector and number	Electromagnetic type, 3
	Injector identification mark	DEKA <134>, KMN230B <3A9>
	Starter relay <Vehicles without AS&G system>	Contact switch type
	Starter cut relay <Vehicles with AS&G system>	Contact switch type
	Starter control relay <Vehicles with AS&G system>	Contact switch type
	Capacitor relay <Vehicles with AS&G system>	Contact switch type