Engine control unit

Engine control unit
An engine control unit (ECU), also called an engine control module (ECM), is a device which controls multiple systems of an internal combustion engine in a single unit. Systems commonly controlled by an ECU include the fuel injection and ignition systems.
The earliest ECUs (used by aircraft engines in the late 1930s) were mechanical-hydraulic units, however most 21st century ECUs use digital electronics.
Functions
The main functions of the ECU are typically:
Fuel injection system
Ignition system
Idle speed control (typically either via an idle air control valve or the electronic throttle system)
Variable valve timing and/or variable valve lift systems
The sensors used by the ECU include:
accelerator pedal position sensor
camshaft position sensor
coolant temperature sensor
crankshaft position sensor
knock sensors
inlet manifold pressure sensor (MAP sensor)
intake air temperature
intake air mass flow rate sensor (MAF sensor)
oxygen (lambda) sensor
throttle position sensor
wheel speed sensor
Secondary
Other functions include:
Launch control
Fuel pressure regulator
Rev limiter
Wastegate control and anti-lag
Theft prevention by blocking ignition, in response to input from an immobiliser
In a camless piston engine (an experimental design not currently used in any production vehicles), 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 unitized and automated device to manage multiple engine control functions simultaneously was the 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 6 controls used to initiate hard acceleration with one control, however the system could cause surging and stalling problems.
Usage in motor vehicles
In the early 1970s, the Japanese electronics industry began producing integrated circuits and microcontrollers used for controlling engines. The Ford EEC (Electronic Engine Control) system, which utilized the Toshiba TLCS-12 microprocessor, went into mass production in 1975.
The first Bosch engine management system was the Motronic 1.0, which was introduced in the 1979 BMW 7 Series (E23) 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 (a closed-loop carburettor) and ignition system. By 1988, Delco Electronics was the leading producer of engine management systems, producing over 28,000 ECUs per day.
Usage in aircraft engines
Such systems are used for many internal combustion engines in other applications. In aeronautical applications, the systems are known as "FADECs" (Full Authority Digital Engine Controls). 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.
See also
Air-fuel ratio meter
Check engine light
List of auto parts
On-board diagnostics (OBD)
Powertrain control module (PCM)
References
Power control
Engine technology
Fuel injection systems
Engine components
Onboard computers