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An engine control unit (ECU), also called an engine control module (ECM), is a device that controls various subsystems of an
internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal comb ...
. Systems commonly controlled by an ECU include the
fuel injection Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of a fuel injector. This article focuses on fuel injection in reciprocating piston and Wankel rotary engines. All c ...
and ignition systems. The earliest ECUs (used by aircraft engines in the late 1930s) were mechanical-hydraulic units; however, most 21st-century ECUs operate using
digital electronics Digital electronics is a field of electronics involving the study of digital signals and the engineering of devices that use or produce them. It deals with the relationship between Binary number, binary inputs and outputs by passing electrical s ...
.


Functions

The main functions of the ECU are typically: *
Fuel injection Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of a fuel injector. This article focuses on fuel injection in reciprocating piston and Wankel rotary engines. All c ...
system *
Ignition system Ignition systems are used by heat engines to initiate combustion by igniting the fuel-air mixture. In a spark ignition versions of the internal combustion engine (such as petrol engines), the ignition system creates a spark to ignite the fuel-ai ...
* 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 An inlet manifold or intake manifold (in American English) is the part of an internal combustion engine that supplies the fuel/ air mixture to the cylinders. The word ''manifold'' comes from the Old English word ''manigfeald'' (from the Anglo- ...
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 A rev limiter is a device fitted in modern vehicles that have internal combustion engines. They are intended to protect an engine by restricting its maximum rotational speed, measured in revolutions per minute (RPM). Rev limiters are Engine contr ...
* 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 Bayerische Motoren Werke AG, trading as BMW Group (commonly abbreviated to BMW (), sometimes anglicised as Bavarian Motor Works), is a German multinational manufacturer of vehicles and motorcycles headquartered in Munich, Bavaria, Germany. Th ...
in 1939 ''Kommandogerät'' system used by the
BMW 801 The BMW 801 was a powerful Nazi Germany, German Air-cooled engine, air-cooled 14-cylinder-radial engine, radial aircraft engine built by BMW and used in a number of German Luftwaffe aircraft of World War II. Production versions of the Radial e ...
14-cylinder
radial engine The radial engine is a reciprocating engine, reciprocating type internal combustion engine, internal combustion engine configuration in which the cylinder (engine), cylinders "radiate" outward from a central crankcase like the spokes of a wheel. ...
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 circuit An integrated circuit (IC), also known as a microchip or simply chip, is a set of electronic circuits, consisting of various electronic components (such as transistors, resistors, and capacitors) and their interconnections. These components a ...
s and
microcontroller A microcontroller (MC, uC, or μC) or microcontroller unit (MCU) is a small computer on a single integrated circuit. A microcontroller contains one or more CPUs (processor cores) along with memory and programmable input/output peripherals. Pro ...
s used for controlling engines. The Ford EEC (Electronic Engine Control) system, which utilized the
Toshiba is a Japanese multinational electronics company headquartered in Minato, Tokyo. Its diversified products and services include power, industrial and social infrastructure systems, elevators and escalators, electronic components, semiconductors ...
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 Chevrolet ( ) is an American automobile division of the manufacturer General Motors (GM). In North America, Chevrolet produces and sells a wide range of vehicles, from subcompact automobiles to medium-duty commercial trucks. Due to the promi ...
and
Buick Buick () is a division (business), division of the Automotive industry in the United States, American automobile manufacturer General Motors (GM). Started by automotive pioneer David Dunbar Buick in 1899, it was among the first American automobil ...
engines to control their fuel system (a closed-loop carburetor) 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 "
FADEC A full authority digital engine (or electronics) control (FADEC) is a system consisting of a digital computer, called an "electronic engine controller" (EEC) or " engine control unit" (ECU), and its related accessories that control all aspects of a ...
s" (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 This is a list of auto parts, which are manufactured components of automobiles. This list reflects both fossil-fueled cars (using internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the c ...
* On-board diagnostics (OBD) *
Powertrain control module A power-train control module, abbreviated PCM, is an automotive industry, automotive component, a control unit, used on motor vehicles. It is generally a combined controller consisting of the engine control unit (ECU) and the transmission contro ...
(PCM)


References

{{Automotive engine , expanded Power control
Control unit The control unit (CU) is a component of a computer's central processing unit (CPU) that directs the operation of the processor. A CU typically uses a binary decoder to convert coded instructions into timing and control signals that direct the op ...
Fuel injection systems Control uni Onboard computers