Open loop

Open loop fueling is used in cars equipped with narrow band O2 sensors to determine the injector on time w/o using feedback from the sensors. Generally, it is based on the amount of air metered by the mass air flow sensor.

Motronic will go open loop under any of the following conditions

1. At start
2. When load > RLLRUN + TRAB delay time
3. When req lambda != 1

Note that there are other open loop conditions, such as during idle under certain circumstances, and at fuel-cutoff during overrun.