Computer Control of Gasoline Engine


A gasoline engine produces power through the explosion of a mixture of gasoline and air. The three essential elements for a gasoline engine to produce power are the following
1. Good air-fuel mixture
2. Good compression
3. Good spark
To achieve these three elements simultaneously, it is important to precisely control the formation of the air-fuel mixture and the timing of the sparks. Before 1981, the only engine control system in existence was the EFI (Electronic Fuel Injection), which used a computer to control the fuel injection volume. In addition to the EFI, there are now various computer-controlled systems, including the ESA (Electronic Spark Advance), ISC (Idle Speed Control), diagnostic systems, etc.
Toyota uses a computer-controlled system called the TCCS (Toyota Computer- Controlled System) to optimally control the fuel injection, ignition timing, drivetrain, brake system, and other systems in accordance with the operating conditions of the engine and the vehicle.
Process of Computer Control
For the computer to function properly, it requires a comprehensive system comprised of various input and output devices. On an automobile, sensors such as a water temperature sensor or an air flow meter correspond to the input device. And actuators such as injectors or igniters correspond to the output device. At Toyota, the computer that controls a system is called an ECU (Electronic Control Unit). The computer that controls the engine is called an engine ECU (or ECM*Engine Control Module). The sensors, actuators, and the engine ECU are connected with wiring harnesses. Only after the engine ECU processes the input signals from the sensors and outputs control signals to the actuators can the entire system operate as a computer-controlled system. *The ECM is SAE (Society of Automotive Engineers) terminology.

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