NOZZLE AS-UNIT INJECTOR 7C0340 - Caterpillar

Detonation is engine knock that occurs after combustion has occurred. The excessive mechanical stress and thermal stress can reduce the service life of the engine. There are several possible causes of detonation. Examples are a rich air/fuel mixture, overload, a high compression ratio, and high inlet manifold air temperature.Combustion of the air/fuel mixture prior to the spark is a premature ignition. A hot spot in the combustion chamber can be the cause. Possible sources of premature ignition are an incorrect spark plug, an incorrectly installed spark plug, and deposits in the combustion chamber. Detonation can be the result of premature ignition. The premature ignition effectively advances ignition timing.Although a sensor may indicate the presence of detonation, the problem could be a premature ignition. An indication of detonation can also be caused by excessive mechanical engine noise.The ECM monitors detonation from 0-30 deg ATDC for each cylinder. Doing so avoids detecting vibrations not related to detonation. Therefore, the "Block Tap" method of testing the detonation sensors does not work for the G3500C Engines.For information on testing the detonation sensors, refer to the engine Troubleshooting manual.