诊断发动机机械异响故障的方法有温度法、速度法、负荷法、听诊法、观察排气颜色法、改变润滑条件法、电路实验法及更换合格器件法等。这些方法既能直接诊断异响,还能使不明显的异响变得突出,使较为明显的异响变弱或消失。另外,还要根据被诊断的是新车、在用车,还是刚刚修好的车来确定诊断的重点和诊断方法。还要注意观察汽车技术状况变化情况以选 Methods of diagnosing engine mechanical abnormalities include temperature method, speed method, load method, auscultation method, observation of exhaust color method, change of lubrication condition method, circuit experiment method and replacement of qualified device method. These methods not only can directly diagnose the abnormal noise, but also make the obvious abnormal noise become prominent, so that the more obvious abnormal noise weakens or disappears. In addition, but also to be diagnosed with a new car, the car, or just to fix the car to determine the diagnosis of the focus and diagnostic methods. Also pay attention to observe the changes in the technical conditions of the car to choose