一辆北京现代SONATA乘用车,采用V形六缸2.7 L排量的发动机,累计行程4000km。怠速时发动机产生有规则的抖动,使用空调时,发动机抖动更严重,并且排气管有“突突”声,尾气呛人。首先用HI-SCAN故障诊断仪测试ECM系统,诊断仪中无该系统的故障代码显示;读取各传感器的数据流,氧传感器的电压有不正常的跳动现象,时而在0.1～0.9V间跳动,时而在0.1～4.6V间跳动。结合排气的症状,说明发动机燃烧不良,混合气的空燃比不正常。影响空燃比的因素很多,如点火系统、燃油系统及进气系统等,由于检测仪中无故障代码显示,说明控制单元和传感器均无问 A Beijing Hyundai SONATA passenger car, with V-shaped six-cylinder 2.7 L displacement engine, a total of 4000 km. Engine idling at regular jitter, the use of air conditioning, the engine jitter more serious, and the exhaust pipe “bump” sound, exhaust choking. First, use the HI-SCAN fault diagnostic tester to test the ECM system. The fault code of the system is not displayed in the diagnostic instrument. The data flow of each sensor is read, and the voltage of the oxygen sensor has abnormal beating phenomenon, sometimes beating between 0.1 and 0.9V , Sometimes beating between 0.1 ~ 4.6V. Combined with exhaust symptoms, indicating poor combustion of the engine, the mixture of air-fuel ratio is not normal. Many factors affect the air-fuel ratio, such as ignition system, fuel system and intake system, due to no fault code detector, indicating that the control unit and the sensor are not asked