Method of detecting abnormality in exhaust gas recirculation control system of internal combustion engine and apparatus for carrying out the same

摘要

In an internal combustion engine equipped with an exhaust gas recirculation control system including an exhaust gas recirculation passage connected to an exhaust pipe and an intake pipe of the engine and an exhaust gas recirculation control valve disposed in the exhaust gas recirculation passage for selectively closing and opening the exhaust gas recirculation passage, a method and an apparatus for diagnosing the exhaust gas recirculation system as to occurrence of an abnormality on the basis of a change in pressure or air flow rate within the intake pipe which is brought about by actuation of the exhaust gas recirculation control valve. By actuating the exhaust gas recirculation control valve in a diagnosis enabling operation state of the engine, it is determined whether the change in the pressure or air flow rate reaches a preset value within a predetermined time. Occurrence of an abnormality in the exhaust gas recirculation system is decided unless the change reaches the preset value within the predetermined time.