FAILURE DIAGNOSING DEVICE FOR EXHAUST GAS RECYCLING DEVICE

摘要

An exhaust gas recirculation system connects an exhaust system of an internal combustion engine to a downstream side of a throttle valve of an intake system by an exhaust gas recirculation passage. The amount of an exhaust gas to be recirculated to the intake system from the exhaust system is adjusted by controlling the degree of opening of a control valve provided in the exhaust gas recirculation passage. When a predetermined abnormality diagnosis condition is met, an abnormality diagnosing apparatus for the exhaust gas recirculation system performs actuation control of the control valve in such a way as to gradually change the degree of opening of the control valve and detects the amount of a change in an amount of intake air or the amount of a change in intake pressure in a predetermined period after initiation of actuation control of the control valve. The abnormality diagnosing apparatus determines that there is an abnormality in the exhaust gas recirculation system when the detected amount does not exceed a predetermined decision value.