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The effects of injector deposits, combustion chamber deposits (CCD), and intake valve deposits (IVD) on exhaust emissions, fuel economy and engine performance have long been recognized in engine and fuel/detergent design. Because important elements of the engine design such as injector position, exhaust gas recirculation (EGR) ratio, and air fuel ratio (AFR) differ from those in port fuel injection (PFI) engines, direct injection spark-ignition (DISI) engines require specific evaluation methods. However, little data is available regarding engine deposits in the more recently produced DISI engines.

The effects of Injector deposits, Combustion Chamber Deposits (CCD), and Intake Valve Deposits (IVD) on exhaust emissions, fuel economy and vehicle performances have long been recognized in engine and fuel/detergent design. Because important elements of engine design such as injector position, exhaust gas recirculation (EGR) ratio, and air fuel ratio (AFR) differ from those of port fuel injection (PFI) engines, current existing test methods are not applicable. Therefore, the demand has been increasing year by year for specific evaluation methods for vehicles with direct injection spark ignition (DISI) engines which have spread rapidly worldwide. Oil and Auto Cooperation for International Standards (OACIS) of Japan selected the Mitsubishi DISI engine (4G93-1.8L) [1] and conducted engine bench tests to investigate the effects of deposits on operating conditions at 40km/h, 70km/h, 140km/h and WOT.