| 摘要 |
PURPOSE:To make it possible to detect a fault with high precision regardless of resolution of an A/D converter by judging whether the intake pipe pressure before and after opening and closing an EGR(exhaust gas reflux) control valve have increased or not and thereby determine whether it is a fault or not. CONSTITUTION:An exhaust gas reflux(EGR) control valve 15 is provided on an EGR passage 14, which makes an exhaust pipe 3 and an inlet pipe 2 of an internal combustion engine communicate with each other, and opens and closes the EGR passage 14. Also provided is an intake air flow control means, namely a by-pass air control valve 12 which changes the intake air flow by a specified quantity determined by the operating condition of the internal combustion engine simultaneously as the EGR control valve 15 has its valve temporarily opened or closed. A fault judging means is also provided to judge whether the inlet pipe pressure before and after opening and closing the EGR control valve 15 has increased or not and determines whether the EGR control valve 15 is faulty or not based on the said judgement. |
