On-Road Monitoring of Low Speed Pre-Ignition 2018-01-1676
To meet increasingly stringent emissions and fuel economy regulations, many Original Equipment Manufacturers (OEMs) have recently developed and deployed small, high power density engines. Turbocharging, coupled with gasoline direct injection (GDI) has enabled a rapid engine downsizing trend. While these turbocharged GDI (TGDI) engines have indeed allowed for better fuel economy in many light duty vehicles, TGDI technology has also led to some unintended consequences. The most notable of these is an abnormal combustion phenomenon known as low speed pre-ignition (LSPI). LSPI is an uncontrolled combustion event that takes place prior to spark ignition, often resulting in knock, and has been known to cause catastrophic engine damage. LSPI propensity depends on a number of factors including engine design, calibration, fuel properties and engine oil formulation. Several engine tests have been developed within the industry to better understand the phenomenon of LSPI. While data from these tests have greatly increased the industry’s knowledge about LSPI, they may not accurately represent LSPI as it occurs while the vehicle is in actual service. This is because the industry tests are conducted on highly controlled engine dynamometers, often using special calibrations. In this work, a vehicle is fully instrumented with a high-speed data acquisition system to monitor LSPI. The vehicle is then operated on public roads with commercially available, pump gasoline for approximately 65,000 miles (104,607 km). Results indicate that LSPI, as it occurs in real world vehicle use, shows some similarities and differences from LSPI that occurs in laboratory engine tests. Additionally, the transient nature of the on-road testing presented a significant departure from the steady-state engine laboratory testing. This difference necessitates the development of a new method for identifying LSPI cycles in real world environments. Finally, results from this work will help the industry develop solutions to LSPI which are effective in the field.