| 摘要 |
PURPOSE: A method for controlling a feedback of an air/fuel ratio of an engine is provided to effectively reduce NOx by controlling the air/fuel ratio at a nitrogen oxide generating region. CONSTITUTION: First, whether an operation area of an engine is within a feedback area through output voltage of a first oxygen sensor(S310) is determined. If the engine is operated in the feedback area, a first feedback control is carried out(S312). Then, output voltage of a second oxygen sensor is monitored. Rich/lean determining voltage is corrected based on output voltage of the second oxygen sensor(S316). Output voltage of the second oxygen sensor is monitored so as to detect whether NOx is increased. Then, an air/fuel ratio feedback control is carried out according to the amount of detected NOx.
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