| 摘要 |
PURPOSE: To provide an exhaust gas recirculation system that has a diagnosing means for obtaining reliable and most suitable information concerning performances of the engine. CONSTITUTION: When certain conditions exist, an exhaust gas recirculating system is diagnosed based upon temperature values 30 detected in the exhaust gas return duct. In order to examine a flow quantity of the exhaust gas return duct, actual temperature values of the exhaust gas return duct are compared 32 with the standard value. The differences of them are low pass filtered 34 in connection with the value of load. When the conditions for a diagnosis are satisfied 37, whether the exhaust gas recirculating system is in order is determined 39, 40 based upon if these differences reach the threshold values 38. Furthermore, based on these differences, sealing states of an exhaust gas return valve are likewise examined. |
