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Internal Diesel Injector Deposits (IDID) in compression ignition engines have been widely studied in the past few years. Published results indicate that commonly observed IDID chemistries may be replicated using full-scale engine tests and subsequently fuel injection equipment (FIE) operated on non-fired electric motor driven test stands. Such processes are costly, complex and by nature can be difficult to repeat. The next logical simplification is to replicate IDID formation using laboratory-scale apparatus that recreate the appropriate chemical reaction process under well controlled steady state conditions. This approach is made more feasible by the fact that IDID, unlike nozzle hole coking, are not directly exposed to gasses involved in the combustion process. The present study uses an instrument designed to measure thermal oxidation stability of aviation turbine fuels to successfully replicate the deposit chemistries observed in full-scale FIE.

A variety of additives are used in automotive diesel fuel to meet specification limits and to enhance quality. For example, lubricity additives and cold flow improvers are used to meet specifications whilst diesel detergents further enhance the quality of the fuel. Recently, several premium fuels that use high levels of diesel detergents and, in some cases, cetane improver have been introduced in the market place. The purpose of the work carried out was to assess the potential impact of these additives on vehicle performance. In order to do this, a fuel free of any additive was treated with very high levels of all the diesel fuel additives currently used to meet specification limits and to enhance diesel fuel performance. A common rail vehicle using an advanced common rail system was then driven in a controlled manner for 50.000 km. Emissions and driveability tests took place at 0km to provide baseline data.