Abstract: Due to high temperature and acid substance in exhaust, gasoline usually produces deposits on the chamber and gasoline jet of intake air system in engines of a car, carbonating on the jet, even blocking the jet, make engine fail to start and run. The methods of selecting optimum engine design have less effect on reducing deposits and carbonating than does that of adding detergent-dispersant additive into gasoline. Anew compound──ureido-urethane is synthesized by reacting di-iso-cyanate with alcohols and amines. After experiments of selecting optimum reaction condition, testing solubility and percentage of relative oxidation,and evaluating in the PFI imitating device. The results show that the detergent-dispersant property of that compound is superior to the new product of USA(paradyne 748) and compound produced in Shanghai.

Key words: Ureido-urethane, Detergence, Dispersity, Port fuel injector simulating rig test