Effect of cold start emissions from gasoline-fueled engines of light-duty vehicles at low and high ambient temperatures: Recent trends

The cold-start condition is an important factor affecting vehicle emissions from gasoline direct injection (GDI) and port fuel injection (PFI) vehicles. This paper studied the recent trends in cold-start emissive behavior with the impact of changes in ambient temperature over the advance technology GDI and PFI vehicles. This research surveys the approaches taken to reduce engine-out emissions and tailpipe emission challenges during cold-start and transient operation using technological advancement. It was found that ambient temperature had a significant influence on cold start emissions especially when the combustion temperature was lower, and when the air/fuel mixture was very rich at very low temperature conditions. Some vehicular emissions increased by 10 times as the temperature varied from +30 degrees C to -7 degrees C and fuel consumption increased as well. GDI vehicles exhibit lower fuel consumption than PFI vehicles but emit more PM mass and solid PN. These results indicate that the particulate emissions from PFI vehicles should not be neglected compared to those from GDI vehicles, especially in a cold environment.