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
Michaelmas term Michaelmas term Michaelmas term is the first academic term of the academic year in a number of English-speaking universities and schools in the northern hemisphere, especially in the United Kingdom. Michaelmas term derives its name from the Feast of St Michael and All Angels, which falls on 29 September. The term runs from September or October to Christmas. The term is also the name of the first of four terms into which the legal year is divided by the Courts of England and Wales and the Courts of Northern Ireland. While the name is not used in the legal systems