Study of Deposit Control Additive Efficacy in Gasoline Direct Injection Engines

There is an increasing adoption of Direct-injection spark-ignition (DISI) engines in the market, which per 2024 EPA Automotive Trends Report represents 73% of new vehicles sold in the US. And while it is well accepted that DISI offers advantages over Port fuel injection (PFI) technology in meeting stringent CO2 emissions and fuel economy requirements set by the EPA, DISI engines are also associated with increased formation of injector deposits. These deposits may foul injectors and accumulate on the injector tip causing distorted spray patterns and diffusive combustion. Ultimately, this leads to engine performance deterioration and increased harmful emissions. To control deposit formation, detergent-type chemistries are added to the fuel in small amounts. Deposit control additives (DCAs) function by preventing the formation of deleterious injector deposits as well as removing existing ones. Standardized protocols describing the assessment of DCA in controlling injector deposits have been developed by industry in both the US and Europe. When used at recommended concentrations, DCA showed some engine performance and emission benefits over untreated base fuel. On the other hand, we have demonstrated that engine performance can be fully recovered with the use of higher DCA concentrations, accompanied by improved fuel economy and reduced particulate and total hydrocarbon emissions. This further confirms previous findings that, although DCA increases gum levels in the fuel, higher concentrations of DCAs improve injector cleanliness enough to outweigh any negative impacts from the increased gum content.