In this paper emission control techniques are presented to meet emission regulations of Euro I meanwhile modification plans are provided for the light duty gasoline vehicles in use.

3—2005,the emission tests on simulations of oxygen sensor deterioration,drop in the function of catalytic converter and misfire are included in the on-board diagnosis(OBD) system test for light-duty gasoline vehicles.

By analyzing the emission data of light-duty gasoline vehicles,the features of emission control technology at State-Ⅰ,State-Ⅱand State-Ⅲthree emission regulation stages are studied.

The paper is going to expound new requirements of China in-use gasoline vehicle emission control by analyzing important issues from the process of establishing new gasoline vehicle emission standards.

In this paper, we take Xian as example for explaining that emission pollutant of light duty gasoline vehicles affect environment of Xian city.

3—2005 Limits and measurement methods for emissions from light-duty vehicles(Ⅲ,Ⅳ phases for China),the effects of the differences of emission limits in type I test between phase Ⅲ and phase Ⅳ and the different judging methods for different cases on the result of conformity of production(COP) assessment are analyzed.

By calculation and analysis being relative to fuel economy in automobile engineering theory,some shortages of measurement methods of fuel consumption for light-duty vehicles in use are indicated.