Ding, H., Zhang, W., Ma, X., Shuai, S. et al., "The Impact of GDI Injector Deposits on Engine Combustion and Emission," SAE Technical Paper 2017-01-2248, 2017.
Gasoline direct injection (GDI) engine technology is now widely used due to its high fuel efficiency and low CO2 emissions. However, particulate emissions pose one challenge to GDI technology, particularly in the presence of fuel injector deposits.In this paper, a 4-cylinder turbocharged GDI engine in the Chinese market was selected and operated at 2000rpm and 3bar BMEP condition for 55 hours to accumulate injector deposits. The engine spark timing, cylinder pressure, combustion duration, brake specific fuel consumption (BSFC), gaseous pollutants which include total hydro carbon (THC), NOx (NO and NO2) and carbon dioxide (CO), and particulate emissions were measured before and after the injector fouling test at eight different operating conditions.Test results indicated that mild injector fouling can result in an effect on engine combustion and emissions despite a small change in injector flow rate and pulse width. It was found that the combustion duration increased with a decrease of combustion efficiency and higher BSFC. Higher NOx emission and lower THC emission can be found when injector is fouled. Particulate number (PN) emissions at high engine load significantly increases after the accumulation of the injector deposits.