Micro Computer Unit (MCU)
The MCU, mounted beneath right side dash panel, monitors the system's sensors and switches and, based upon mode of operation, generates a control signal to the main air bleed stepper motor mounted in carburetor. The MCU also receives a voltage signal from negative side of coil. Until voltage equivalent to a predetermined RPM is received, the system will remain in Open Loop mode.
When the system is in Open Loop mode, the air/fuel mixture will be based on a predetermined ratio dependent upon engine RPM and input signals from engine sensors. When system is switched to Closed Loop mode, the MCU monitors oxygen sensor and engine sensor input to determine proper air/fuel mixture.