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In emerging markets, Port Fuel Injection (PFI) technology retains a higher market share than Gasoline Direct Injection (GDI) technology. In these markets fuel quality remains a concern even despite an overall improvement in quality. Typical PFI engines are sensitive to fuel quality regardless of brand, engine architecture, or cylinder configuration. One of the well-known impacts of fuel quality on PFI engines is the formation of Intake Valve Deposits (IVD). These deposits steadily accumulate over time and can lead to a deterioration of engine performance. IVD formation mechanisms have been characterized in previous studies. However, no test is available on a state-of-the-art engine to study the impact of fuel components on IVD formation. Therefore, a proprietary engine test was developed to test several chemistries. Sixteen fuel blends were tested. The deposit formation mechanism has been studied and analysed.

The effects of lubricant oil and fuel properties on low speed pre-ignition (LSPI) occurrence in boosted S.I. engines were experimentally evaluated with multi-cylinder engine and de-correlated oil and fuel matrices. Further, the auto-ignitability of fuel spray droplets and evaporated homogeneous fuel/oil mixtures were evaluated in a combustion bomb and pressure differential scanning calorimetry (PDSC) tests to analyze the fundamental ignition process. The work investigated the effect of engine conditions, fuel volatility and various lubricant additives on LSPI occurrence. The results support the validity of aspects of the LSPI mechanism hypothesis based on the phenomenon of droplets of lubricant oil/fuel mixture (caused by adhesion of fuel spray on the liner wall) flying into the chamber and autoigniting before spark ignition.

The interest on improving fuel efficiency of vehicles is increasing day by day. Fuel efficiency standard for diesel commercial vehicles such as buses and trucks was published in Japan. Using a fuel efficient engine lubricant is one of the effective paths and there are several 5W-30 diesel engine lubricants in Japanese market which are advertised to give a benefit on fuel efficiency against 10W-30 oil. During the development of 5W-30 fuel efficient diesel engine oil, it was revealed that the piston underside was significantly blackened by the detergency engine test (JASO M 336: 2014). In this paper, the causative agent which blackened the piston underside was investigated and the formulation to inhibit this blackening phenomenon was studied. Through several tests, it was considered that use of poly methacrylate based viscosity index improver and ester type friction modifier deteriorated detergency performance.