故障一: 北京BJ2020汽车所用492Q发动机,因曲轴正时齿轮记号打错造成发动机怠速不稳,化油器有轻度回火。 一、故障现象: 洛阳孟津县某乡政府一辆北京BJ2020汽车大修后出现怠速不稳,化油器有轻度回火故障。修理者先后给用户更换过6个化油器、5个分电器,并联加装电容均未见效,检查配气时间,原配气刻度正时记号对正。 二、故障分析: Fault 1: Beijing BJ2020 492Q engine used in the car, due to crankshaft timing gear mark wrong engine idle speed instability, carburetor mild tempering. First, the fault phenomenon: Luoyang Mengjin County, a township government Beijing BJ2020 after a major overhaul idling instability carburetor mild tempering failure. The repairer has changed 6 carburetors to the user, 5 distributor, parallel installed capacitors are not effective, check the gas distribution time, the original valve calibration timing mark. Second, failure analysis: