Closed-loop control

The closed-loop control of the engine EFI system is a real-time triangulation between the oxygen sensor, the computer and the fuel quantity control device. The oxygen sensor “tells” the air/fuel ratio of the computer mixture, and the computer issues a command to the fuel quantity control device to adjust the air/fuel ratio to the theoretical value (14.7:1). This adjustment often exceeds the theoretical value, the oxygen sensor senses it, reports it to the computer, and the computer reissues the order back to 14.7:1. Because each adjustment cycle is very fast, the air-fuel ratio does not deviate from 14.7:1. Once it is running, this closed-loop adjustment continues. The closed-loop controlled EFI engine can ensure that the engine not only has good dynamic performance, but also can save fuel because it can always run the engine under ideal conditions (the air-fuel ratio is not too much from the theoretical value).