Engine control unit


An engine control unit, also called an engine control module, is a device that controls various subsystems of an internal combustion engine. Systems commonly controlled by an ECU include the fuel injection and ignition systems.
The earliest ECUs were mechanical-hydraulic units; however, most 21st-century ECUs operate using digital electronics.

Functions

The main functions of the ECU are typically:
The sensors used by the ECU include:
Other functions include:
In a camless piston engine, the ECU has continuous control of when each of the intake and exhaust valves are opened and by how much.

Early systems

One of the earliest attempts to use such a unitised and automated device to manage multiple engine control functions simultaneously was created by BMW in 1939 Kommandogerät system used by the BMW 801 14-cylinder radial engine which powered the Focke-Wulf Fw 190 V5 fighter aircraft. This device replaced the six controls used to initiate hard acceleration with one control, however the system could cause surging and stalling problems.
Despite its limitations, the Kommandogerät represented a significant step toward integrated engine management by mechanically linking throttle position to fuel delivery, ignition timing, supercharger control, and propeller pitch. The system used cams, gears, and pressure-based regulators to compute appropriate settings across different operating conditions, effectively acting as an early analog computer. Although it lacked the adaptability and precision of later electronic systems, the Kommandogerät demonstrated the feasibility of reducing pilot workload through automated coordination of multiple engine parameters. Its underlying concept influenced subsequent developments in aircraft and automotive engine control, eventually leading to electronically controlled systems such as full authority digital engine control and modern engine control units.

Use in motor vehicles

In the early 1970s, the Japanese electronics industry began producing integrated circuits and microcontrollers used for controlling engines. The Ford EEC system, which used the Toshiba TLCS-12 microprocessor, entered mass production in 1975.
The first Bosch engine management system was the Motronic 1.0, which was introduced in the 1979 BMW 7 Series This system was based on the existing Bosch Jetronic fuel injection system, to which control of the ignition system was added.
In 1981, a Delco Electronics ECU was used by several Chevrolet and Buick engines to control their fuel system and ignition system. By 1988, Delco Electronics was the leading producer of engine management systems, producing over 28,000 ECUs per day.

Use in aircraft engines

Such systems are used for many internal combustion engines in other applications. In aeronautical applications, the systems are known as "FADECs". This kind of electronic control is less common in piston-engined light fixed-wing aircraft and helicopters than in automobiles. This is due to the common configuration of a carbureted engine with a magneto ignition system that does not require electrical power generated by an alternator to run, which is considered a safety advantage.