Measurement and Analysis on Emissions from an EFI Gasoline Engine under Transient Conditions

The volumetric percents of CO, HC, NO_X, CO₂ and O₂ from the exhaust of an EFI gasoLine engine were measured and analyzed under the working conditions of its cold-start, cold-acceleration-deceleration, warm-deceleration and warm-acceleration. The results show that: A large amount of HC and CO is emitted from the engine under cold-start condition. During this period, the catalytic converter doesn´t yet begin to work. So the control of exhaust depends mainly on the preparation of mixture and the optimization of the combustion process. During cold-acceleration-deceleration, there are peak values in the curves of CO, HC and NO_X emissions, showing that it is necessary to avoid these operations as much as possible in the actual running. Under warm-deceleration, there is a large peak value in the curve of HC emissions, showing that it is necessary to research the strategy of cutting off fuel further. And the emphasis of exhaust control is NO_X under warm-acceleration condition.