Fuel Property Requirements for Multiport Fuel Injector Deposit Cleanliness

A comprehensive test program has been conducted to determine the effect of fuel properties for injector deposit. Eleven fuel property factors, and the influence of injector temperature and leakage rate were evaluated.

A laboratory accelerated test procedure has been developed for the evaluation. The procedure was shown to adequately reflect the effect of fuel properties and injector operating conditions. Injector deposits were greatly affected by diene number, olefin content, and sulfur content. The addition of ethanol increased deposits but the addition of methanol and MTBE did not. Detergents prevented deposit accumulation as long as the diene number was low. As a summary of the test program, three grades of fuel limits have been determined to forecast deposit-forming tendencies. Also determined were requirements regarding both injector leakage and injector temperature.