Open loop

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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, and whether the desired AFR is stoichiometric (lambda=1) or not.

Motronic will go open loop under any of the following conditions

  • At motor start
  • When load > RLLRUN + TRAB delay time
  • 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.