Chip tuning refers to changing or modifying an EPROM chip in a car's or other vehicle's electronic control unit (ECU) to achieve better performance, whether it be more power, cleaner emissions, or better fuel economy. EPROM. The small quartz window admits UV light during erasure. ... This article or section does not cite its references or sources. ... In automotive electronics, an electronic control unit (ECU) is an embedded microcomputer that controls one or more of the electrical subsystems in a vehicle. ...

This was done with early engine computers in the 1980s and 1990s. Today, the term chip tuning can be misleading, as people will often use it to describe ECU tuning that does not involve swapping the chip. Modern ECUs can be tuned by simply updating their software through a standard interface, such as OBDII. This procedure is commonly referred to as engine or ECU tuning. ECUs are a relatively recent addition to the automobile, having first appeared in the late 1970s. An engine is something that produces an effect from a given input. ... The NASA Columbia Supercomputer. ... Computer software (or simply software) refers to one or more computer programs and data held in the storage of a computer for some purpose. ...

As technology advanced, so did the electronics that go into cars. The ECU in a modern automobile, together with advanced engine technology, makes it possible to control many aspects of the engine's operation, such as spark timing and fuel injection. The ECU may also control electronic throttle control (drive-by-wire), valve timing, boost control (in turbocharged engines), ABS, the automatic transmission, and the electronic stability control system. // Fuel injection is a means of metering fuel into an internal combustion engine. ... A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. ... Air foil bearing-supported turbocharger cutaway made by Mohawk Innovative Technology Inc. ... An anti-lock braking system (ABS) is a system on motor vehicles which prevents the wheels from locking while braking. ... An automatic transmission is an automobile gearbox that can change gear ratios automatically as the vehicle moves, thus freeing the driver from having to shift gears manually. ... In mechanics, a transmission or gearbox is the system of gears and/or the hydraulic system (called variously hydrodynamic, fluid or automatic transmission) that transmits mechanical power from a prime mover—such as an engine or electric motor—to a typically rotary output device at a lower angular momentum but...

Most performance gains are realized by adjusting the ignition timing advance to suit high-octane gasoline without pre-ignition detonation or pinging. Manufacturers design for a specific octane level and may limit performance accordingly. Changing the engine tune specifically to suit better fuel may result in slight increases in performance. If a car already has an "anti-knock" sensor, then there is nothing to be gained by modifying the ECU mapping.

Another reason to change the ECU map is if there are extensive engine or intake or exhaust modifications to the car.

A common misconception is that the ECU can be tuned to provide different power maps optimized for different driving courses (e.g. race tracks). In fact, once the ECU is tuned for optimal torque at all RPM ranges, there is no reason to "de-tune" the ECU for any RPM. A poorly tuned ECU can result in decreased performance, driveability, and may even cause engine damage.

See also

• Engine tuning

Engine tuning or engine building is the adjustment, modification or design of internal combustion engines to yield optimal performance, either in terms of power output or economy. ...

External links

• HowStuffWorks article on car computers
• Vehicle modifications and legal requirements - Victoria, Australia
• Description of the SAE J2534-1 standard applicable to all 2004 & up vehicles
• LabView VIs for developing test systems with vehicle PassThru (J2534-1)
• Custom Unichip ECU programming
• Examples of effect of chip tuning
• Powerchip Performance Engine Tuning
• Custom chip tuning with additional ECU functions including immobilising and switchable maps