Experimental Optimization of the Cold Start for the EcoBoost Engine

An experimental methodology was developed and applied to optimize the EcoBoost turbo-charged direct injection engine cold start. Specific focus was on minimizing hydrocarbon and NO_x emissions and IMEP variation for the catalyst heating portion of the engine start. The methodology uses steady state single cylinder engine testing with conditioned fluids to screen main factors affecting the emissions and stability responses. The main factors include injector spray pattern design, piston crown design, injection timing, fuel rail pressure, valve timing, and port heat flow. Following the steady state testing, a transient single cylinder engine test was conducted at the optimized conditions to verify emissions and engine stability. This step typically produces results more closely correlated to actual engine starts when compared with the steady state single cylinder engine testing due to better approximation of the engine thermal conditions. Finally, the optimized hardware and operating strategy are run on a transient multi-cylinder engine cold start test to identify any further optimization required to meet program emissions and engine performance targets.