| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a failure diagnosis device for an engine capable of accurately performing open failure diagnosis of a control valve at high frequency without operating the air pump. <P>SOLUTION: ECU 30 judges permission of execution of open failure diagnosis of the control valve 27 during steady state operation of an engine 1 under which the control valve 27 is controlled to close and air fuel ratio feedback control is executed. Under the permission judgment of execution of open failure diagnosis, when change of line pressure P of a secondary air lead in passage 25 is detected, atmospheric air flow in quantity Qs is operated based on the change of line pressure P and atmospheric air flow in quantity Qg is operated based on change of air fuel ratioλand fuel injection quantity Ti. If difference between the atmospheric air flow in quantities Qs, Qg is set value or less, open failure of the control valve 27 is judged. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
