Cold-start emissions of an SI engine using ethanol–gasoline blended fuel

The effects of ethanol–gasoline blended fuel on cold-start emissions of an SI engine were studied. During cold-start, the ECU controls fuel injection rate based on cooling water temperature and intake air temperature, which were carefully controlled during the experiment. More ethanol content in the blended fuel makes the air–fuel mixture leaner and also affects the RVP value. The engine could be started stably with E5, E10, E20, and E30. The HC and CO emissions decreased significantly with more ethanol than 20% added. However, for E40 the engine idling became unstable because the air–fuel mixture was too lean. Therefore, the ethanol content in gasoline for best cold-start emissions was determined to be at least 20 per cent but no greater than 30 per cent.