| 摘要 |
PURPOSE:To accurately diagnose troubles by continuing operation of an internal combustion engine even after OFF of the engine key switch, and judging troubles in an exhaust gas recycling device when the operating condition of the internal combustion engine does not change in spite of execution of increasing opening control of an exhaust gas recycling control valve. CONSTITUTION:When a key switch 56 is off, an exhaust gas recycling control valve 20 is fully opened by an exhaust gas recycling control device 62 through a step motor 33. At this time, if the step motor 33 is troubled or a sticking trouble is generated in a valve element 24, stall of an internal combustion engine is not generated, as the exhaust gas recycling control valve 20 can not be fully opened. Hereby, when the speed of the internal combustion engine 1 detected with an engine speed sensor 51 is not same as the predetermined value 0 or near to 0 or lower than it, the internal combustion engine 1 is continued to operate, and the trouble of the exhaust gas recycling control device 62 is judged. |
