Impact of Detergent Type, Detergent Concentration and Friction Modifiers on PM-PN Emissions in an SI Engine using EEPS

Three TOP TIERTM gasoline detergent control additives of differing chemistries were tested for their impact on particulate matter emissions in terms of particulate mass (PM) and particulate number (PN) at operating conditions representative of road load, cold start and high load on a 2.0L, 4-cylinder gasoline direct injection (GDI) spark ignition (SI) engine. The PM-PN emissions were measured using an Exhaust Emissions Particle Sizer (EEPS). Detergent control additives (DCAs) are gasoline additives used to prevent and clean combustion chamber and injector deposits in gasoline spark ignition (SI) engines. All three gasoline additives were tested at each operating condition at three different treatment rates. In addition, one of the additives was tested with a friction modifier (FM). The results showed that of the treatment rates tested, the lowest allowable concentration (LAC) for all additives requires the least time for the emissions to settle. However, the impact of the gasoline additives on PM-PN emissions is not linear and changes with additive concentration depending on the additive chemistry and operating condition. The friction modifier resulted in a significant impact on both particulate mass and particulate number at the road load operating condition.