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The effects of lubricating oil on friction and engine-out emissions in a light-duty 2.2L compression ignition direct injection (CIDI) engine were investigated. A matrix of test oils varying in viscosity (SAE 5W-20 to 10W-40), friction modifier (FM) level and chemistry (MoDTC and organic FM), and basestock chemistry (mineral and synthetic) was investigated. Tests were run in an engine dynamometer according to a simulated, steady state FTP-75 procedure. Low viscosity oils and high levels of organic FM showed benefits in terms of fuel economy, but there were no significant effects observed with the oils with low MoDTC concentration on engine friction run in this program. No significant oil effects were observed on the gaseous emissions of the engine. PM emissions were analyzed for organic solubles and insolubles. The organic soluble fraction was further analyzed for the oil and fuel soluble portions.

A laboratory test procedure was developed, and used to evaluate the deposit-forming tendencies of liquid fuels on a metal surface, and to identify deposit precursors in fuel. The impetus for this work was deposit formation in multiport fuel injection(MPFI) systems. Results from our laboratory test correlated well with those from engine dynamometer tests. Deposit formation is shown to be caused by the oxidation, condensation, and precipitation of unstable hydrocarbon species in the fuel. The immediate precursors for deposit formation were determined, based on liquid chromatographic separation and GC/MS analysis, to be oxygenated hydrocarbons included in the fuel.