| 摘要 |
PROBLEM TO BE SOLVED: To further surely detect overheating of a catalyst when the catalyst of a cleaning device attached to an exhaust system of an engine is overheated.SOLUTION: For each ignition cycle, a misfire rate Cmf is held when a required time change amount ΔT30[i] is not larger than a threshold ΔT30ref2 and the misfire counter Cmf is incremented by only a value of 1 when the required time change amount ΔT30[i] is larger than the threshold ΔT30ref2 (S310 to S330), and a misfire rate Rmf is set so that it becomes smaller when a fuel injection amount increase determination flag F[i] is a value of 1 compared to a case when the fuel injection amount increase determination flag is a value of 0 (S340). Then, when an ignition counter Ci reaches a threshold Ciref or larger (S370), it is determined whether or not a cleaning catalyst is overheated by comparing the misfire counter Cmf and a misfire rate integrated value Rmfsum as an integrated value of the misfire rate Rmf (S410 to S430).SELECTED DRAWING: Figure 5 |
