How Engine Control Unit (ECU) Works - Full Explained

How Engine Control Unit (ECU) Works - Full Explained


ENGINE CONTROL UNIT is the brain of the engine that controls all the functioning of the engine. It serves several functions which includes regulating and maintaining the amount of fuel and air in the fuel injection part and helps in increasing horsepower of the engine.
The main function of ECU or Engine Control Unit is the controlling of series of function of actuators on an internal combustion engine and ensuring the excellent engine performance. The Engine Control Unit is also called Power train control unit.
Within the Engine Bay ECU takes the values from A multitude of sensors and then interpret that data by using multidimensional Performance maps And in this way adjust the engine actuators accordingly.
This is also responsible for the best Engine performance. Engine Control Module or ECM is the same as Engine Control unit the difference is that if we named overall combined section of control unit in engine then we called it as Engine Control Module or ECM.

ECU is the integral part of EFI or Electronic Fuel Injection(a type of fuel injection system commonly used among cars).Electronic Fuel Injection can be divided into sub-systems namely Air induction system , fuel delivery System and the electronic control system. And from here the function of the ECU starts.

Functioning of ECU

Controlling the air-fuel mixture :This is the one of the most Important function of ECU as it controls the fuel mixture used by the engine. It determines the amount of air-fuel mixture injecting into the engine. The program received the necessary data and computes it and gives the appropriate amount of mixture. It also decides whether it is the right time to deliver the air-fuel mixture in a proper ration or not. This process is also called injection duration.

Controlling the ignition timing: ECU adjust the exact timing of the spark or the ignition timing to provide the better power and economy. ECU detects itself whether there is the problem in the compression stroke or not and works according and set the timing of ignition. This is mainly happened in the condition whenever there is unburned air-fuel mixture left and it is subjected to combination of heat and pressure .This results in detonation also known as Knocking or pinking . ECU detects the knocking and delayed the time of spark to prevent it.

Controlling on Idle speed and variable valve timing: Most cars have also built in control system in their ECU for controlling idle speed. Idle speed is controlled through the programmable throttle stop. Apart from the controlling on idle speed ECU also controls the timing at which the valve open or close in the engine cycle. The best suitable and appropriate timing of opening and closing of valve helps in increasing the power and economy of the engine.

ECU Also Increases the Torque and BHP .As it governs the fuel injection into the cylinder,it is programmed for the efficient performance of the engine at any environment whenever ECU encounters increase in load then it initiates a signal for more fuel injection & thus engines generates more BHP.