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
Archaic Greece of the eighth century BC until the beginning of the fifth century BC, with the foundation of the Olympic Games in 776 BC and the Second Persian invasion of Greece in 480 BC forming notional start and end dates. The Archaic period was long considered to have been less important and historically interesting than the Classical period, and was primarily studied as a precursor to it. More recently, however, Archaic Greece has come to be studied for its own achievements. With this reassessment of the significance of the Archaic period, some scholars have objected to the term "archaic", due to