Method for optimizing the air/fuel ratio under non-steady conditions in an internal combustion engine

In a control system for correcting fuel/air ratio of an internal combustion engine having a pre- and post-exhaust gas catalyst probe and means for adjusting said fuel/air ratio in response to ratios sensed by said probes to achieve a desired fuel/air ratio the improvement being means for providing non-steady sense of operation correction signal to said adjusting means comprising:

• means for storing a plurality of sets of correcting control values and time values of the duration which the post-catalyst probe indicates an undesirable fuel/air ratio, for a plurality of sets of specified engine-operating conditions in the non-steady range;
• means for determining non-steady range of operation;
• means for sensing engine operating conditions;
• means for reading a set of a correction control value and a time for said sensed engine operating conditions;
• means for modifying said read correction control value to achieve a desired fuel/air ratio and providing said signal to said adjusting means in response to a determined non-steady range;
• means for measuring the time the post-catalyst probe indicates an undesirable fuel/air ratio using said modified correction value;
• means for comparing said measured time value with said read time value;
• and
• means for storing said modified correction value and measured time value for the set of sensed engine operating conditions if said measured time value is less than said read time value.