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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.

A comprehensive investigation into why gasoline fuel injectors fail in the field due to deposit formation has led to the development of a robust fuel injector design. Analysis of field failures provided critical clues as to why fuel injectors form deposits. The development of a repeatable test and a repeatable deposit forming fuel allowed the confirmation of these clues and the testing of design improvements. This combination of test cycle and fuel allowed for a reduced test time while providing sufficient sensitivity to differentiate between injector design improvements. Confirmation of design improvements was completed on a stationary vehicle using both commercially available gasoline and a formulated deposit forming fuel.