| 摘要 |
PROBLEM TO BE SOLVED: To improve accuracy of individual cylinder air fuel ratio control and accuracy of individual cylinder air fuel ratio abnormality diagnosis by increasing estimation accuracy of individual cylinder air fuel ratio in a system estimating air fuel ratio of each cylinder (individual cylinder air fuel ratio) based on output of an air fuel ratio sensor installed in an exhaust gas merging part of an engine. SOLUTION: Estimation error of estimated air fuel ratio of each cylinder due to drop of response of the air fuel ratio sensor 37 is accurately corrected by correcting estimated air fuel ratio of each cylinder according to response of the air fuel ratio sensor 37 after accurately correcting estimation error of the estimated air fuel ratio of each cylinder due to change of engine operation conditions by correcting estimated air fuel ratio of each cylinder according to the engine operation conditions (for example, engine speed, load and the like). Accuracy of individual cylinder air fuel ratio control and accuracy of individual cylinder abnormality diagnosis are improved by performing individual cylinder air fuel ratio control and individual cylinder air fuel ratio abnormality diagnosis with using estimated air fuel ratio of each cylinder of which estimation accuracy is improved by the corrections. COPYRIGHT: (C)2008,JPO&INPIT
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