Low-speed pre-ignition in gasoline, turbo-charged, direct injection engines: An analysis of engine testing data

A review of an extensive set of engine testing data was conducted in order to study low-speed, pre-ignition (LSPI) phenomena observed in turbo-charged, direct injection gasoline engines. A wide range of engine makes and sizes were tested by Ricardo Ltd. Analysis of the test results, further in-house experiments and inferences drawn from the wider literature, were used to estimate the impact of a range of variables upon LSPI. A table of weighted variables was developed in order to determine the conditions required to initiate LSPI on the engine testbed. This has led to shorter test times during durability testing as well as a better understanding of the mechanisms behind LSPI. Some challenges faced when trying to accurately and consistently measure this phenomenon are outlined. Finally, a method to identify LSPI is proposed along with recommendations for suitable control responses to LSPI events encountered in a vehicle application.