Powertrain Management: Description and Operation
SYSTEM OUTLINEThe engine control system utilizes a microcomputer and maintains overall control of the engine, transaxle 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 OX1B and OX2B of the engine control module.
4. RPM signal circuit
Camshaft position and crankshaft position are detected by the camshaft position sensor and crankshaft position sensor. Camshaft position is input as a control signal to TERMINAL G22+ of the engine control module, and engine RPM is input into 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 TERMINAL VTA of the engine control module.
6. Vehicle speed circuit
The 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 TERMINAL BATT of the engine control module. With the ignition SW turned on, the voltage for engine control module start-up power supply is applied to TERMINAL +B of the engine control module via the EFI main relay.
8. A/C SW signal circuit
The A/C amplifier inputs the A/C operations into TERMINAL AC1 of the engine control module.
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 sensor and the signal is input into TERMINAL KNK1 as a control signal.
12. Air fuel ratio signal system
The air fuel ratio is detected and input as a control signal into TERMINALS AF1A+, AF2A+ of the engine control module.
13. Fuel cut in a collision
The system receives the collision signal from center airbag sensor assembly in the vehicle has a collision and stops the fuel pump operation on the side of the engine control module.
2. CONTROL SYSTEM
- SF1 system
The SF1 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 of the engine control module to operate the injector (Inject the fuel). The SF1 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 IGT1, IGT2, IGT3, IGT4. 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 sensors to improve detection performance of the sensors.
The engine control module evaluates the signals from each sensor, and outputs current to TERMINALS HT1B and HT2B to control the heater.
- Idle speed control system
The idle speed control system (Rotary solenoid type) increases the RPM and provides idling stability for fast idle-up when the engine is cold and when the idle speed has dropped due to electrical load, etc. The engine control module evaluates the signals from each sensor, outputs current to TERMINAL RSD, and controls the idle speed control valve.
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 malfunction indicator lamp.
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.