I've always heard people say that the ECU of a car is something.

other people say brush ECU, like research car, always to the professional terminology to study,

ECU is a car computer, brush car computer can improve the power, also can reduce power, see demand.
The simple principle is as follows.
1. Automobile engine operation is controlled by the automobile computer (ie ECU).
2.ECU control the engine's intake, fuel injection, ignition time, etc., so as to determine the efficiency of engine operation and power, torque and so on.
3. Engine work in various speed, gear, load, temperature and other conditions ' corresponding ' air intake, fuel injection, ignition time and other information, in a database record in the ECU, this database is called "M.A.P."
4. The essence of the brush ECU is to modify this "M.A.P." ---database. Change the control engine data, affect the engine's operation, within the engine can withstand the range, to achieve the desired effect.

In my understanding, the ECU is a car-mounted small computer that remembers the operation information and control information of the vehicle. They're going to have to rely on these things, haha.

I've always heard people say that the ECU of a car is something.