Investigation of Low-Speed Pre-Ignition in Boosted Spark Ignition Engine

This paper presents the results of study low-speed Pre-ignition (LSPI) on highly supercharged spark ignition engines. It was investigated on both a gasoline direct injection (GDI) engine with turbo and a port fuel injection (PFI) engine with turbo to find the individual characteristics of LSPI. In terms of the PFI engine, influence of different parameters control strategy such as air-fuel ratio and injection timing on pre-ignition was investigated. In terms of the GDI engine, influence of different control strategies such as injection quantity, first and second injection timing, the second injection ratio, coolant temperature, exhaust valve closing (EVC) and intake manifold temperature (MAT) were investigated. In addition, CFD analysis was extensively used to understand test results including wall film, air-fuel ratio distribution and temperature distribution at top dead centre (TDC). For GDI engine in this paper, pre-ignition (PI) results from the combine action of wall film, temperature distribution at TDC and air- fuel ratio distribution at TDC. Enrich air-fuel rate have effective suppression of low-speed Pre-ignition on the GDI engine and the PFI engine.