| 摘要 |
PROBLEM TO BE SOLVED: To provide an air-fuel control device which can suitably control the air-fuel ratio of mixture when hydrocarbon is desorbed from an HC adsorbent located in an exhaust system, and which can maintain a satisfactory exhaust gas characteristic, in particular, after a start of an engine. SOLUTION: When it is determined that an HC adsorbent desorbs HC since a desorbing flag is FSDR=1, a predetermined diluting value KCMDHB is calculated from an absolute intake-pipe pressure PBA and an engine speed NE. The predetermined diluted value KCMDHB is set, the higher the diluting degree, the higher absolute intake-pipe pressure PBA. A desired air-fuel ratio factor KCMD is set to the predetermined diluted value KCMDHB (S23), and air-fuel ratio feed back control is carried out so that a detected equivalent ratio KACT is coincident with the desired air-fuel ratio factor KCMD.
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