General System Description

The computerized engine control system is built around an Electronic Control Unit (ECU). The ECU monitors up to 15 inputs and responds with appropriate outputs to manage fuel delivery, ignition timing, and emission control devices. As operating conditions change, the ECU adjusts injector pulse width and ignition timing for optimum performance and fuel economy.

The Multi-Point Fuel Injection System (MPFI) controls fuel delivery. Fuel is injected into the intake manifold before the intake valve in precise amounts through electronically controlled injectors. The injectors are fired simultaneously by the ECU twice every cycle of the engine. The ECU constantly adjusts the amount of fuel injected to meet changing operating conditions by controlling injector pulse width (the length of time the injector is ENERGIZED).

The ECU also adjusts the ignition timing by controlling the ignition coil operation through the ignition control module. The following is a list of ECU inputs and outputs:


ECU INPUTS

- Battery Voltage
- Manifold Absolute Pressure (MAP) Sensor
- Engine Coolant Temperature
- Manifold Air Temperature (MAT) Sensor
- Exhaust Oxygen (O2) Sensor
- Engine Speed (crankshaft position)
- Throttle Position
- Injector Power Signal
- A/C Select Signal
- A/C Request Signal
- Neutral Safety Switch (gear selection-auto trans.)
- Engine Knock Sensor
- Ignition Relay - ON Signal
- Starter Relay - (engine crank signal)
- Vehicle Speed Sensor


ECU OUTPUTS

- Idle Speed Regulator
- B+ Latch Relay
- A/C Control Module
- Fuel Injectors
- EGR Valve Solenoid
- Ignition Control Module (ICM)
- Electric Fuel Pump Relay