Engine control unit

For other uses, see ECU (disambiguation).

An engine control unit (ECU), also called an engine control module (ECM),^[1] 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.

Delco ECU used in General Motors vehicles built in 1996

The earliest ECUs (used by aircraft engines in the late 1930s) were mechanical-hydraulic units; however, most 21st-century ECUs function by 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:^[2]

• 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.^[3][4]

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.^[5] This device replaced the 6 controls used to initiate hard acceleration with one control, however the system could cause surging and stalling problems.^{[citation needed]}

Usage in motor vehicles

In the early 1970s, the Japanese electronics industry began producing integrated circuits and microcontrollers used for controlling engines.^[6] The Ford EEC (Electronic Engine Control) system, which utilized the Toshiba TLCS-12 microprocessor, went into mass production in 1975.^[7]

The first Bosch engine management system was the Motronic 1.0, which was introduced in the 1979 BMW 7 Series (E23)^[8] This system was based on the existing Bosch Jetronic fuel injection system, to which control of the ignition system was added.^[9]

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.^[10] By 1988, Delco Electronics was the leading producer of engine management systems, producing over 28,000 ECUs per day.^[11]

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.^[12]

See also

• Air-fuel ratio meter
• Check engine light
• List of auto parts
• On-board diagnostics (OBD)
• Powertrain control module (PCM)

References

1. "How an Automotive Computer Works". www.2carpros.com. Retrieved 14 May 2023.
2. "Toyota Prius - Engine Control Systems" (PDF). www.autoshop101.com. Retrieved 14 May 2023.
3. Austen, Ian (2003-08-21). "WHAT'S NEXT; A Chip-Based Challenge to a Car's Spinning Camshaft". The New York Times. Retrieved 2009-01-16.
4. "How Proportional Valve Control Module control the oil flow direction". www.genndih.com. Retrieved 2023-06-03.
5. Gunston, Bill (1989). World Encyclopedia of Aero Engines. Cambridge, England: Patrick Stephens Limited. p. 26. ISBN 978-1-85260-163-8.
6. "Trends in the Semiconductor Industry: 1970s". Semiconductor History Museum of Japan. Retrieved 27 June 2019.
7. "1973: 12-bit engine-control microprocessor (Toshiba)" (PDF). Semiconductor History Museum of Japan. Retrieved 27 June 2019.
8. . www.bosch.com. Archived from the original on 23 June 2006.
9. Probst, C. (27 November 1989). Bosch Fuel Injection and Engine Management. Robert Bentley, Incorporated. ISBN 978-0-8376-0300-1. Retrieved 13 May 2023.
10. . www.gmheritagecenter.com. Archived from the original on 3 July 2017.
11. Delco Electronics Electron Magazine, The Atwood Legacy, Spring '89, page 25
12. Pilot's Encyclopedia of Aeronautical Knowledge. Federal Aviation Administration.