Computerized Engine Controls: Notes

Computerized engine control system consists of various input devices which detect vehicle operating conditions. The Electronic Control Module (ECM) monitors input signals received from input devices and sends output signals to regulate air/fuel mixture and other engine control operations. This lowers exhaust emissions, while maintaining fuel economy and driveability.

System incorporates a built-in fail-safe mechanism, self-diagnostic system and back-up function. Fail-safe mechanism substitutes preprogrammed sensor values to the ECM if a sensor fails, thus providing a certain level of engine performance. Self-diagnostic system provides capability of recognizing a system fault and storing a related trouble code in ECM memory for diagnostic purposes. Back-up function of ECM controls operation of fuel injectors on basis of signals from Pressure (MAP) sensor if ECM fails to operate properly.