preignition


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Related to preignition: Spark knock

preignition

[¦prē·ig′nish·ən]
(mechanical engineering)
Ignition of the charge in the cylinder of an internal combustion engine before ignition by the spark.

preignition

The ignition of the fuel-air charge prior to the spark plug firing. Preignition caused by some other ignition source such as an overheated spark plug tip, carbon deposits in the combustion chamber, and, rarely, a burned exhaust valve. All act as a glow plug to ignite the charge. Preignition occurs during the compression stroke, and the engine continues to fire with the ignition system switched off, although probably not all its cylinders. There is no explosion as in a detonation and the rise of temperature and pressure is much greater, probably resulting in catastrophic consequences. Preignition is often experienced when attempting to start a hot engine or during an attempt to shut down a hot engine, and it usually results in a backfire through the intake manifold.
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References in periodicals archive ?
If the determined start of combustion occurred before a 5a surrounding around the median value of start of combustion for all cycles of the respective test run, preignition was detected.
In this case, only a single LSPI event was detected in a different cylinder, and the preignition did not lead to knock combustion.
Limits on Downsizing in Spark Ignition Engines due to Preignition," MTZ, 70: 56-61, 2009.
I also learned how to diagnose fuel injector imbalances across the cylinders, exhaust port issues (leaks and bad gaskets), fouled spark plugs, detonation and preignition (see more about these last two situations in the sidebar on the opposite page).
That will be either a lot of very heavy detonation or more likely preignition.
A Study of Low Speed Preignition Mechanism in Highly Boosted SI Gasoline Engines," SAE Int.
The authors found no significant correlation between base oil group and preignition event frequency.
Our experimental apparatus was the LSPI stationary engine test developed by Southwest Research Institute (SwRI) for the Preignition Prevention Program (P3).