EFI Engine Control 1

The EFl/TCCS system is an electronic control system which provides Toyota engines with the means to properly meter the fuel and control spark advance angle. The system can be divided into three distinct elements with three operational phases. The three system elements are: Input Sensors Electronic Control Unit (A Microcomputer) Output Actuators
  The electronic control system is responsible for monitoring and managing engine functions which were previously performed by mechanical devices like carburetors, vacuum, and centrifugal advance units. In an electronic control system, these functions are managed in three phases. The input phase of electronic control allow the Electronic Control Unit (ECU) to monitor engine operating conditions, utilizing information from the input sensors. The process phase of electronic control requires the ECU to use this input information to make operating decisions about the fuel and spark advance systems. The output phase of electronic control requires the ECU to control the output actuators, the fuel injectors, and igniter to achieve the desired fuel metering and spark timing.