Optimization of cold start automotive fuel economy using a spark timing strategy

Fuel use during the cold start of an automotive engine can be up to three times higher than when the engine is warm due to increased oil viscosity and subsequently increased friction within the engine. In this work, we investigate whether retarding the spark early during the engine warm up, and subsequently sacrificing early fuel economy for greater initial heat release, can have a beneficial impact on the overall fuel economy. Two methods are used here. Firstly, a reduced order, thermal model for the engine at idle is presented and then used to find the optimal spark timing by applying results from optimization theory. A full order model is then used in a dynamic programming approach to validate the analytical results