Abstract: An air/fuel ratio controller for an internal combustion engine including a memory having numbers stored at locations addressed by engine operating points with the locations addressed by the engine operating points being updated during closed loop operation in accord with the value of a closed loop adjustment of the air/fuel ratio. Each memory location in the memory is updated during operation of the engine at the corresponding operating point in accord with an update time constant having a value so that the number stored tracks adjustment value producing the predetermined desired closed loop air/fuel ratio during varying values of engine temperature. The update time constant is varied directly with the value of engine temperature so that the rate of adjustment of the numbers in the memory is greater during engine warmup where engine temperature increases rapidly. The memory is used during closed loop operation to preset the closed loop adjustment at least when the engine first operates at an operating point.