| 摘要 |
PURPOSE:To prevent any misjudgement due to a non-injection or an excessive injection by judging that the exhaust gas recirculation equipment is defective when the detection values sensored by an exhaust gas temperature sensor installed in the exhaust gas recirculating path are below a specified value even if the fuel-injection system is normally operated. CONSTITUTION:Detection values sensored by an air flow meter 6, an engine speed sensor 22, an O2 sensor 17, and a throttle switch 18 for detecting an idle opening, etc. are inputted to a control circuit 10 with which air-fuel ratio feedback corrections are carried out depending on the operating conditions of a fuel injection system. When the throttle switch 18 is ON and the air-fuel ratio feedback correction factor continues to be at the upper or lower limit for more than a preset time, the fuel injection system is judged to be abnormal. And when the fuel injection system is abnormal, a water temperature is above about 80 deg.C, an engine speed is in the specified range, Q/N (Q: intake air flow rate; N: engine speed) is less than the specified level and an intake air flow rate is more than the specified rate and further if the temperature detected by an exhaust gas temperature sensor 17 installed downstream EGR control valve 9 in an exhaust gas reflux path 8 is below the specified limit, an alarm lamp is made to light. |
