Like ordinary computers, it consists of microprocessor (CPU), memory (ROM, RAM), input/output interface (I/O), analog-to-digital converter (A/D) and large-scale integrated circuits such as shaping and driving. To describe it in a simple sentence is "ECU is the brain of a car".
Modifying ECU is to change the engine operation by changing the method of dealing with problems (original ECU program). The so-called "ECU program" is actually a set of algorithms. It is stored in the memory, and the signal converted from the input device by the controller is processed to generate a corresponding command signal and transmitted from the output device. So when we modify the ECU parameters, we actually modify the algorithm.
：
ECU collects the working state information of various parts of the engine through various sensors (including temperature sensor, pressure sensor, speed sensor, flow sensor, position sensor, oxygen sensor, knock sensor, etc.). ) and send it to the ECU through the transmission line. After receiving these signals, ECU will analyze them.
You will know the information about the functional status and operation of engine components, and then automatically calculate which actuators should do what in this state according to the pre-written program, and then issue instructions to the actuators to order them to work.
References:
Baidu encyclopedia-automobile computer