Pre-ignition Pre-ignition Pre-ignition (or preignition) in a spark-ignition engine is a technically different phenomenon from engine knocking, and describes the event wherein the air/fuel mixture in the cylinder ignites before the spark plug fires. Pre-ignition is initiated by an ignition source other than the spark, such as hot spots in the combustion chamber, a spark plug that runs too hot for the application, or carbonaceous deposits in the combustion chamber heated to incandescence by previous engine combustion events. The phenomenon is also referred to as 'after-run', or 'run-on' or sometimes dieseling, when it causes the engine to carry on running after
Henderson archaic pigeon extension, the dodo. The pigeon became extinct following human colonisation of Henderson, an event that had occurred by 1050 CE. Two of the other three species of pigeon on the island also disappeared, as did other birds. Henderson archaic pigeon The Henderson archaic pigeon ("Bountyphaps obsoleta"), or Henderson Island archaic pigeon, is an extinct bird in the Columbidae, or pigeon family. It was described in 2008 as a new genus and species from subfossil remains found on Henderson Island in the Pitcairn Group of south-eastern Polynesia. The genus was named for both the ship HMS "Bounty" with which, following the