NUT 6K9316 - Caterpillar

This service procedure assists the field technician in performing detonation analysis on a G3600 Engine using an oscilloscope. The procedure provides instructions for setting the Fluke 97 ScopeMeter and probe signal connections. The procedure provides instruction for analyzing the detonation signals to distinguish combustion detonation and mechanically induced, or "false" detonation.Detonation sensors are mounted on each bank of the engine to monitor the engine vibrations. The sensor outputs an electrical signal of the frequency and amplitude of the mechanical vibrations. The SI Timing Control (TCM) monitors all the detonation sensors to determine the detonation level. This detonation level is used by the G3600 Engine Control to provide protection. The control will retard the ignition timing for light detonation levels and will shut down the engine for severe detonation.The detonation signal indicates the amplitude and frequency of the mechanical variations. This information is used to determine the presence and severity of the detonation. Most mechanical vibrations produce a frequency outside of the detonation frequency range. Occasionally, some mechanically induced vibrations fall within the detonation frequency range and are interpreted as combustion detonation. This mechanically induced, or "false", detonation generates control action causing reduced performance or engine shutdowns.