Method of and system for lean-controlling air-fuel ratio in electronically controlled engine

摘要

In a method of and system for lean-controlling an air-fuel ratio in an electronically controlled engine, wherein the air-fuel ratio is feedback-controlled to the lean side from the stoichiometric air-fuel ratio in accordance with an output from a lean sensor generating an output signal substantially proportional to the concentration of oxygen in the exhaust gas, when it is necessary to vary a target air-fuel ratio, a target control value of an output from the lean sensor is corrected in accordance with the required variation value and the air-fuel ratio is feedback-controlled whereby the output from the lean sensor can become the corrected target control value, so that satisfactory feedback control of the air-fuel ratio can be effected even when the target air-fuel ratio is varied to a value other than the normal value.