Fuel trim adaptation

The fuel trim adaptation has 3 self-learning integrators, which all depend on engine speed and engine load (rkat, frau, frao). The engine speed and engine load operating areas for rkat, frau and frao are shown in Fig 2.

Depending on the enable condition for each integrator, the deviation of the fuel control system from its stoichiometric A/F ratio is "learned".

Fig 1: Fuel System - Overview Fuel Trim Adaptation And Fuel Injection Calculation

Courtesy of BMW OF NORTH AMERICA, INC.

Fig 2: Fuel System - Fuel Trim Adaptation Operating Areas RKAT, FRAU And FRAO

Courtesy of BMW OF NORTH AMERICA, INC.