To determine the optimal amount of fuel supply according to operating conditions and a target air-fuel ratio.
When a step S053 determines an internal combustion engine main body 1 as being out of idling (NO) and a step S057 determines a vehicle as being running (NO), a step S059 conducts table retrieving for adding/ subtracting term DKEVAPO2 corresponding to a target air-fuel ratio coefficient KCMD. The leaner the target air-fuel ratio coefficient KCMD is, the smaller the DKEVAPO2 is set. As a result, when comparison of an actual air-fuel ratio coefficient KACT with the target air-fuel ratio coefficient KCMD by a step S077 shows that an actual air-fuel ratio coefficient KACT is lean (YES), fluctuations in purge concentration coefficient KAFEV can be made gentle by a step S081; thus it is possible to prevent a drop in engine speed, an engine stall, or the like due to over lean.
KITAJIMA SHINICHI
KONNO FUMIHIKO
MATSUBARA ATSUSHI
WAKASHIRO TERUO
TAKAHASHI HIDEYUKI
FUKUCHI HIRONAO
NAKAMOTO YASUO
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