Editing ECU (section)

=What is the ECU?=

The ECU is the computer that manages your engine.
The letters "ECU" stand for "Engine Control Unit".
The ECU uses closed-loop control, a control scheme that monitors outputs of a system to control the inputs to a system, managing the emissions and fuel economy of the engine (as well as a host of other parameters).
Gathering data from dozens of different sensors, the ECU knows everything from the coolant temperature to the amount of oxygen in the exhaust.
With this data, it performs millions of calculations each second, including looking up values in tables, calculating the results of long equations to decide on the best spark [[timing]] and determining how long the fuel injector is open.
The ECU does all of this to ensure the lowest emissions and best mileage.