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 engine control module (ECM) calculates the air/fuel ratio, fuel injector on-time, based on the signal from the oxygen sensor. This allows the air/fuel ratio to stay very close to 14.7:1.