Abstract: A managed fuel air control system is provided that transitions between a closed loop stoichiometric A/F mode and an open loop lean A/F mode of operation. When conditions permit open loop lean operation, the engine A/F is ramped from stoichiometric to the desired lean A/F. Periodically, while operating in the open loop lean mode, the system returns to the closed loop stoichiometric mode to update an open loop correction factor used during the open loop lean mode. The time at stoichiometric is usually limited to the time it takes to correct errors in calibration data that have occurred during open loop operation. During lean operation, the adaptive corrections learned at stoichiometric A/F are applied.