Powertrain Management: Description and Operation

System Outline

The engine control system utilizes a microcomputer and maintains overall control of the engine, transmission etc. An outline of the engine control is given here.

1. Input Signals

1. Engine coolant temp. signal circuit
The engine coolant temp. sensor detects the engine coolant temp. and has a built-in thermistor with a resistance, which varies according to the engine coolant temp.. The engine coolant temp. which is input into TERMINAL THW of the engine control module as a control signal.

2. Intake air temp. signal circuit
The intake air temp. sensor is installed in the mass air flow meter and detects the intake air temp. which is input as a control signal to TERMINAL THA of the engine control module.

3. Oxygen density signal circuit
The oxygen density in the exhaust emission is detected by the heated oxygen sensors and input as a control signal to TERMINALS OX1A, OX2A, OX1B and OX2B of the engine control module.

4. RPM signal circuit
Camshaft position is detected by the camshaft position sensor and its signal is input to TERMINAL G2 of the engine control module as a control signal.

Also,engine RPM is detected by the crankshaft position sensor and is input as a control signal to TERMINAL NE.

5. Throttle position signal circuit
The throttle position sensor detects the throttle valve opening angle as a control signal, which is input into TERMINALS VTA and VTA2 of the engine control module.

6. Vehicle speed circuit
(A/T)
Signals detected by ABS speed sensors are input into the combination meter through skid control ECU. Then it is delivered to the engine control module through MPX communication.

(M/T)
The vehicle speed sensor (Combination meter) detects the vehicle speed and inputs a control signal to TERMINAL SPD of the engine control module.

7. Battery signal circuit
Voltage is constantly applied to TERMINALS BATT and +BM of the engine control module. If you turn on the ignition SW, the current goes from TERMINAL MREL of the engine control module to the EFI relay and put on the relay, and the voltage related to the engine control module operation is supplied to TERMINALS +B and +B2 of the engine control module through the EFI relay.
The current flowing through the IGN fuse flows to TERMINAL IGSW of the engine control module.

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

9. Stop light SW signal circuit
The stop light SW is used to detect whether the vehicle is braking or not and the signal is input into TERMINAL STP of the engine control module as a control signal.

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

11. Engine knock signal circuit
Engine knocking is detected by knock sensors and the signal is input into TERMINALS KNK1 and KNK2 of the engine control module as a control signal.

2. Control System

- SFI system
The SFI system monitors the engine condition through the signals input from each sensor to the engine control module. And the control signal is output to TERMINALS #10, #20, #30, #40, #50 and #60 of the engine control module to operate the injector (Inject the fuel). The SFI system controls the fuel injection operation by the engine control module in response to the driving conditions.

- ESA system
The ESA system monitors the engine condition through the signals input to the engine control module from each sensor. The best ignition timing is decided according to this data and the memorized data in the engine control module and the control signal is output to TERMINALS IGT, IGT2 and IGT3. 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 oxygen sensors to improve detection performance of the sensors. The engine control module evaluates the signals from each sensor, and outputs current to TERMINALS HT1A, HT2A, HT1B and HT2B to control 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 control module judges the engine speed by the signals from each sensor and outputs signal to the TERMINAL ACIS of the engine control module and controls the VSV (ACIS).

- ETCS-i
The ETCS-i controls the engine output at its optimal level corresponding to the opening of the accel. pedal under all driving conditions.

- Fuel pump control system
The engine control module operation outputs to TERMINAL FPR and controls the FUEL PMP relay. Thus controls the fuel pump drive speed in response to conditions.

- MPX
The MPX communicates with the combination meter, A/C control assembly, as well as body ECU of the multiplex communication system .

3. Diagnosis System

With the diagnosis system, when there is a malfunction in the engine control module 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 light.

4. Fail-Safe 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 fail-safe system either controls the system by using data (Standard values) recorded in the engine control module memory or else stops the engine.