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 Southwest Archaic Southwest The Archaic Southwest was the culture of the southwestern United States between 6500 BC and 200 AD (approximately). The Paleo-Indian tradition before that dates from 10,500 BC to 7500 BC. The Southwestern United States during the Archaic time frame can be identified or defined culturally in two separate ways: As the climate warmed at the end of the Ice Age, mammoths and large animals such as horses and camels began to disappear. Hunter/gatherers gradually adapted to these changes, supplementing their diet with a variety of plant foods and smaller game. The Archaic people used nets and the atlatl