### System Outline

This system utilizes an engine ECU and maintains overall control of the engine, transmission and so on. An outline of the engine control is explained here.

1.Input Signals

(1)Water temp. signal circuit

The water temp. sensor detects the engine coolant temp. and has a builtin thermistor with a resistance which varies according to the engine coolant temp. The engine coolant temp. is input into TERMINAL THW of the engine ECU as a control signal.

(2)Intake air temp. signal circuit

The intake air temp. sensor is installed in the air flow meter and detects the intake air temp., which is input as a control signal to TERMINAL THA of the engine ECU.

(3)Oxygen sensor signal circuit

The oxygen density in the exhaust emission is detected and is input as a control signal from the heated oxygen sensors (Bank 1 sensor 2 and bank 2 sensor 2) to TERMINALS OX1B and OX2B of the engine ECU.
To stabilize detection performance by the heated oxygen sensors, the heated oxygen sensors are warmed. This heater is also controlled by the engine ECU (HT1B and HT2B).

(4)RPM signal circuit

Camshaft position is detected by the crank position sensor (RH), crank position sensor (LH) and their signals are input to TERMINALS VV1+ and VV2+ of the engine ECU as control signals. Also, the engine RPM is detected by the crankshaft position sensor installed in the cylinder block and the signal is input into TERMINAL NE+ of the engine ECU as a control signal.

(5)Throttle signal circuit

The throttle position sensor (Inside of throttle body assembly) detects the throttle valve opening angle as a control signal, which is input into TERMINALS VTA1 and VTA2 of the engine ECU.

(6)Air fuel ratio signal circuit

The air fuel ratio is detected and input as a control signal into TERMINALS AFL+ and AFR+ of the engine ECU.

(7)Accelerator signal circuit

The Accelerator position sensor detects the accelerator pedal opening degree. And the control signal is input in the TERMINALS VPA and VPA2 of the engine ECU.

(8)Battery signal circuit

Voltage is constantly applied to the battery terminal of the engine ECU. When the ignition SW is turned to ON, voltage for engine ECU operation is applied via the MAIN relay to TERMINALS +B and +B1 of the engine ECU.

(9)Intake air volume signal circuit

Intake air volume is detected by the air flow meter and the signal is input to TERMINAL VG of the engine ECU as a control signal.

(10)Stop lamp SW signal circuit

The stop lamp SW is used to detect whether or not the vehicle is braking and the signal is input into TERMINAL STP of the engine ECU as a control signal.

(11)Starter signal circuit

To confirm whether the engine is cranking, the voltage applied to the starter motor during cranking is detected and the signal is input into TERMINAL STA of the engine ECU as a control signal.

(12)Engine knock signal circuit

Engine knocking is detected by knock control sensors (Bank 1 and bank 2) and the signal is input into TERMINALS KNK1 and KNK2 as a control signal.

(13)VVTi signal circuit

The camshaft timing oil control valves (LH exhaust side, LH intake side, RH exhaust side and RH intake side) detects the real valve timing. And the control signal is input in TERMINALS OC1+ and OC2+ of the engine ECU.

2.Control System

*EFI system

The EFI system monitors the engine condition through the signals, which are input from each sensor to engine ECU. The best fuel injection volume is decided based on this data and the program memorized by the engine ECU, and the control signal is output to TERMINALS #10, #20, #30, #40, #50 and #60 of the engine ECU to operate the injector (Inject the fuel). The EFI system produces control of fuel injection operation by the engine ECU in response to the driving conditions.

*ESA system

The ESA system monitors the engine condition through the signals, which are input to the engine ECU from each sensor. The best ignition timing is decided according to this data and the memorized data in the engine ECU, and the control signal is output to TERMINALS IGT1, IGT2, IGT3, IGT4, IGT5 and IGT6. This signal controls the igniter to provide the best ignition timing for the driving conditions.

*Heated oxygen sensor heater control system

The heated oxygen sensor heater control system turns the heater on when the intake air volume is low (Temp. of exhaust emissions is low), and warms up the heated oxygen sensor to improve detection performance of the sensor.
The engine ECU evaluates the signals from each sensor, current is output to TERMINALS HT1B and HT2B, controlling the heater.

*Air fuel ratio sensor heater control system

The air fuel ratio sensor heater control system turns the heater on when the intake air volume is low (Temp. of exhaust emission is low), and warms up the air fuel ratio sensor to improve detection performance of the sensor.
The engine ECU evaluates the signals from each sensor, current is output to TERMINALS AFL+ and AFL, controlling the heater.

*ACIS

ACIS includes a valve in the bulkhead separating the surge tank into two parts. This valve is opened and closed in accordance with the driving conditions to control the intake manifold length in two stages for increased engine output in all ranges from low to high speeds.
The engine ECU judges the engine speed by the signals from each sensor and outputs signals to the TERMINAL ACIS to control the VSV (ACIS).

*ETCSi

The ETCSi controls the engine output at its optimal level corresponding to the opening of the throttle valve under all driving conditions.

*Fuel pump control

The engine ECU outputs current to TERMINAL FPR and controls the F/PMP relay and fuel pump drive speed in response to driving conditions.

3.Diagnosis System

With the diagnosis system, when there is a malfunction in the engine ECU signal system, the malfunctioning system is recorded in the memory. The malfunctioning system can be found by reading the code displayed by the check engine warning lamp.

4.FailSafe System

When a malfunction has occurred in any system, if there is a possibility of engine trouble being caused by continued control based on the signals from that system, the failsafe system either controls the system by using data (Standard values) recorded in the engine ECU memory or else stops the engine.