Störungsdiagnoseeinrichtung und Verfahren zur Störungsdiagnose bei einem Abgasrückführunssteuersystem

摘要

In a trouble diagnosis device for an exhaust gas return control system in which a returning amount of exhaust gas is changed at a predetermined value to obtain a variation between operating conditions of the engine under before thus changing and under after thus changing, and the variation is compared with a predetermined value, thereby to determine whether or not the exhaust gas return control system is out of order. A variation rate in the detection value of the operating conditions of the engine is obtained every predetermined period of time, and when the variation rate thus obtained exceeds a predetermined rate, the trouble diagnosis operation for the exhaust gas return control system is suspended.