Engine Test for Accelerated Fuel Deposit Formation on Injectors Used in Gasoline Direct Injection Engines

An accelerated fuel injector deposit formation test was developed to understand fuel deposit formation on fuel injectors for Gasoline Direct injection engines. As part of the test development, both a side mount and a central mount Gasoline Direct injection style 4 cylinder engines were operated in homogeneous mode. Initial attempts to form plugging deposits by running the engine continuously resulted in significant deposits forming on the exterior surface of the Gasoline Direct injection fuel injector tip; however, these deposits did not impact fuel flow.

Ultimately, Gasoline Direct injection injector plugging was successfully accomplished using a test similar to the Port Fuel Injector test cycle presented in SAE 2005-01-3841 (1), “Development of a Robust Injector Design for Superior Deposit Resistance”. Test cycles included run time to reach operating temperature followed by engine soak and cool-down. Engine soak and injector tip temperatures were determined to be the most important factors contributing to injector plugging.

This engine test, used in conjunction with Delphi's gasoline deposit-forming fuel, resulted in an accelerated, repeatable test that formed fuel deposits resulting in fuel injector lean flow shift. Fuel deposit location and chemistry replicated deposits found on fuel injectors operated in the real world.