An Intake Valve Deposit (IVD) Engine Test Development to Investigate Deposit Build-Up Mechanism Using a Real Engine

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 results of this study indicate that addition of C6 to C16 olefins did not increase the deposit mass, unless the oxidation stability of the resultant gasoline was impaired. The deposit analyses suggested aromatics (including PAH) with a high boiling point or used at high concentrations tend to remain on the valve surface as a deposit. The engine tests also suggest that a small fraction of the base fuel has a disproportionate impact on deposit weight. A high final boiling point of the fuel does not necessarily make a fuel more prone to IVD formation, but rather it depends on the chemical composition of the high boiling components.