Development of a Direct Injection Spark Ignition Engine Test for Injector Fouling 2003-01-2006

Direct Injection Spark Ignition (DISI) engines are known to be sensitive to injector fouling. To evaluate the effectiveness of detergent additives and the influence of fuel parameters on injector fouling, a new DISI engine test has been developed, using a 2.0 l stoichiometric homogeneous DI engine on a test bench. Severe engine running conditions have been found to lead to a high amount of deposits on the injector nozzle over a short period of time (“one day” procedure). Injector fouling is measured using a fuel flow measurement procedure representative of injector operating conditions (opening time and pressure). This procedure has proved to be reliable and repeatable with different gasoline fuels and additives being evaluated. The influence of the base fuel and the effect of the composition and the dosages levels of detergent additives (keep-clean and clean-up properties) are demonstrated with the test method.