| 摘要 |
PROBLEM TO BE SOLVED: To provide a failure detection device of an internal combustion engine capable of properly determining failure to difference in air-fuel ratios when the difference in air-fuel ratios between cylinders is found, while determining deterioration of a catalyst.SOLUTION: During a normal engine operation, a temporary determination mode for determining difference in air-fuel ratios between cylinders on the basis of disorder of output waveform of LAFS22, is implemented in parallel with determination of deterioration of a three-way catalyst 21 under a control condition of learning sensitivity of a general stoichiometric correction factor learning value. When the difference in the air-fuel ratios is determined in the temporary determination mode, the mode is switched to a main determination mode, and learning sensitivity of the stoichiometric correction factor learning value is set to a sensitive side, so that the difference in the air-fuel ratios between the cylinders is determined with higher reliability on the basis of the stoichiometric correction factor learning value (=rich treatment counter C2) rapidly increased due to the difference in the air-fuel ratios between the cylinders.SELECTED DRAWING: Figure 3 |
