Closed Loop

The specific values for the above conditions vary with different engines and are stored in the electronically erasable programmable read-only memory (EEPROM). When these conditions are met, the system goes into closed loop operation. In closed loop, the ECM calculates the air/fuel ratio, the fuel injector on-time, based on the signals from the oxygen sensors. This allows the air/fuel ratio to stay very close to 14.7:1.