ECU means Electronic Control Unit which is also known as the black box or Electronic Control Module (ECM). It is the central computer that controls fuel injection system, idle speed control and ignition timing in the contemporary cars especially in the motorcycles. The ECU comes with an 8 bit microprocessor, ROM, input/output interface and RAM. It also obstructs the air conditioner of the car and the EGR systems thereby controls the power sent to the fuel pump. The input sensors supplies the information on barometric pressure, air flow, engine coolant temperature, etc and based on this information ECU decides on the maximum settings for the output actuators like ignition timing, idle speed, injection, etc.