Closed Loop Mode

In this mode, each component in the system is sensitive to the other components. This means that the carburetor is controlled by the vacuum solenoid regulator, which is controlled by ECU in response to a signal from the exhaust gas oxygen sensor in the exhaust manifold, which is reacting to the mixture in the carburetor. When all the components are functioning in this fashion, the system is termed to be in "Closed Loop" mode.