| 摘要 |
PCT No. PCT/JP91/01184 Sec. 371 Date May 1, 1992 Sec. 102(e) Date May 1, 1992 PCT Filed Sep. 4, 1991 PCT Pub. No. WO92/04538 PCT Pub. Date Mar. 19, 1992.An air/fuel ratio control method and system for an internal combustion engine employing first and second air/fuel ratio sensors, respectively upstream and downstream of a catalytic converter, sets and stores learnt correction values, by learning through an averaging process, for an air/fuel ratio correction value by a second air/fuel ratio sensor, stores a degree of progress of learning with respect to each learning, and modifies the learnt correction value with a modification ratio depending upon the degree of progress of learning. Accordingly, both a promotion of the learning and an enhancement of the accuracy of the learning can be achieved, and thus the emission control performance can be improved by progressively reducing an offset at the transition from an inactive state to an active state of the air/fuel ratio feedback control or at the transition of an engine driving range.
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