Search Results

This work presents a follow-up to previous efforts by the authors to investigate the susceptibility of gasoline direct injection (g-di) engines to deposit formation and the effect of those deposits on vehicle performance. A series of injector keep clean and clean up tests in base and additized fuels utilizing the ASTM D 5598 cycle provided a range of injector fouling levels. It is found that the g-di engine employed here is more susceptible to injector deposits than even the sensitive port fuel injected (PFI) engine used as industry reference in the D 5598 procedure. Injector keep clean and clean up performance of several representative deposit control chemistries are evaluated. In order to determine the effect of injector fouling on performance, emissions and driveability tests are performed on the vehicles at varying levels of injector fouling. Regulated emissions, particulates, fuel consumption and driveability are all shown statistically to be linked to injector fouling.

Four 1998 Mitsubishi Carismas, two equipped with direct injection and two with port fuel injection engines, were tested in 20,100 km intervals to determine the effect of mileage accumulation cycle, engine type, fuel and lubricant on vehicle deposits and emissions, acceleration and driveability performance. The program showed that engine fuel system deposits, including specifically those on intake valves, combustion chambers and injectors are formed in higher amounts in the GDI engine than the PFI engine. The fuel additive used reduced injector deposits and combustion chamber deposits in the GDI, but had no significant effect on intake valve deposits, which are affected by crankcase oil formulation. In GDI vehicles, deposited engines were found to have increased hydrocarbon and carbon monoxide emissions and poorer fuel economy and acceleration, but lower particulate emissions.

Four 1998 Mitsubishi Carismas, two equipped with direct injection (GDI) and two with port fuel injection engines (PFI) were tested in a designed experiment to determine the effect of mileage accumulation cycle, engine type, fuel and lubricant type on engine wear and engine oil performance parameters. Fuel types were represented by an unadditised base fuel meeting EEC year 2000 specifications and the same base fuel plus synthetic deposit control additive packages. Crankcase oils were represented by two types (1) a 5W-30 API SJ/ILSAC GF-2 type engine oil and (2) a 10W-40 API SH/CF ACEA A3/ B3-96 engine oil. The program showed that specific selection of oil additive chemistry may reduce formation of intake valve deposits in GDI cars.. In general, G-DI engines produced more soot and more pentane insolubles and were found to be more prone to what appears to be soot induced wear than PFI engines.