Engine Control Module: Description and Operation

The Multiport Fuel Injection (MFI) control system is an electronic fuel metering system with fuel injectors near inlet port of each cylinder. The amount of fuel injection is determined by ECM according to engine speed and intake air-flow quantity measured. The emission control system includes oxygen sensor and catalystic converters. The MFI's three major functions are air-fuel mixture, idle speed and ignition timing control.
When the ignition switch in ON or START, battery voltage is supplied to the ECM and the ECM will ground the coils of the engine control relay. The engine control relay coils energize, the engine control relay contacts close and the battery voltage is supplied to the component (For instance, MAF sensor, Injectors, solenoid valves and fuel pump relay and so on).