汽油机OBD失火检测技术

车载自动诊断系统（OBD）是实行国Ⅲ和国Ⅳ排放标准的核心内容，汽油机失火诊断是OBD的一个重要功能。指出了汽油机失火的原因和危害，分析了汽油机失火检测的3种方法，建立了TU5JP4汽油机曲轴转速检测法的GT—Power仿真模型。结果表明：汽油机失火时，转速和扭矩都会出现短时间的下降，其中扭矩下降更为明显，同时排气中O2浓度升高，CO2的浓度下降。将GT—Power软件应用于发动机失火故障模拟，对失火诊断系统的开发有较好的指导作用。

Research on Gasoline Engine OBD Misfire Detection Technology

On-Board Diagnostics （OBD） system is the key part of the implement of Stage III and IV emission standards, and gasoline misfire diagnostics is one of the most important OBD functions. This paper points out the causes and damages of engine misfire, and analyzes 3 kinds of misfire testing detection methods. The GT-Power simulation model of TU5JP4 gasoline engine crankshaft rotational speed detection is established. The results showed that when gasoline misfire occurred, the speed and torque decreased for a while, in which torque decrease was more obvious. At the same time O2 concentration increased and CO2 concentration decreased. Using GT-Power software in engine misfire simulation has instructive effects on the development of misfire diagnostic system.