| 摘要 |
PURPOSE: To accurately diagnose, with a simple procedure and a low cost, whether exhaust gas passes through an exhaust gas recirculation path when an exhaust gas recirculation valve is opened. CONSTITUTION: An exhaust gas recirculation diagnosing system of an internal combustion engine 10 comprises an exhaust gas recirculation valve AGRV disposed in an exhaust gas recirculation path 13; control means 14 for regulating an opening degree of the exhaust gas recirculation valve; and diagnosing means 16 for detecting whether or not the exhaust gas flows through the exhaust gas recirculation path when the control means opens the exhaust gas recirculation valve. The diagnosing means detects whether or not a misfire frequency of the internal combustion engine increases when the exhaust gas recirculation valve is further opened from a first state and reaches a second state. Since the misfire frequency of the internal combustion engine depends on an exhaust gas recirculation rate, functional ability of the exhaust gas recirculation system can be surely evaluated. |
