改变转速法发动机异响往往在不同的转速下有不同的特点。有的异响在发动机怠速或低速时清晰,而在发动机加速或中等以上转速时混杂不清。有的异响在发动机怠速和缓慢加速时不明显,但当发动机转速由怠速往中速急剧提高时,就显得非常明显。因此,在判断发动机异响时,可以采用反复改 Change the speed method Engine abnormal noise often have different characteristics at different speeds. Some abnormal sound in the engine idling or low speed clear, but in the engine speed or medium speed above mixed. Some abnormal sound in the engine idle speed and slow acceleration is not obvious, but when the engine speed from idle to sharp increase in speed when it becomes very obvious. Therefore, in judging the engine noise, you can use repeated changes