SPRING 9U8614 - Caterpillar

The engine is equipped with an electronic ignition system. The system provides dependable firing and low maintenance. The system provides precise control of the spark and of the ignition timing for each cylinder.
Illustration 1 g02304553
Rear view
(1) ECM
(2) Slave ECM Each cylinder has an ignition transformer. Master ECM (1) controls ignition on the left bank. Slave ECM (2) controls ignition on the right bank. To initiate combustion, each ECM sends a pulse of approximately 100 V to the primary coil of each ignition transformer at the appropriate time and for the appropriate duration. The transformers step up the voltage in order to create a spark across the spark plug electrode.Detonation sensors monitor the engine for detonation. The G3520 Engine has ten detonation sensors. Each sensor monitors two adjacent cylinders. The sensors generate data on vibration that is processed by each ECM in order to determine detonation levels. The master ECM monitors the sensors on the left bank and the slave ECM monitors the sensors on the right bank. The slave ECM communicates the status of the right side sensors to the master ECM. Detonation is only monitored between 9 degrees before top center and 40 degrees after top center. Doing so avoids detecting vibrations not related to detonation.If detonation occurs, the master ECM retards the ignition timing of the affected cylinder or cylinders up to 6 degrees. If a cylinder has been fully retarded for 16 combustion cycles and the cylinder is still detonating, the ECM shuts down the engine. During a detonation shutdown request, the ECM retards the detonating cylinder an additional 6 degrees, not to exceed 10 degrees total.Each ECM provides diagnostics for the ignition system. See the engine's Troubleshooting manual for more information on the diagnostics of the ignition system.Ignition Transformers and Spark Plugs
Illustration 2 g01442611
Side view of a cylinder head
(3) Mounting flange
(4) Ignition transformer
(5) Primary connection
(6) Spark plug
(7) Extension Mounting flange (3) provides a ground for each ignition transformer (4). The ignition harness is connected to primary connection (5). The output from the secondary circuit of the transformer is sent to spark plug (6) through the extension (7).The spark plug does not have a conventional electrode gap that can be adjusted. The spark plug has a precombustion chamber. During the compression stroke, the air/fuel mixture in the cylinder enters holes in the spark plug's precombustion chamber. The secondary circuit of the transformer provides an initial 8,000 to 32,000 V to the spark plug in order to create a spark. The air/fuel mixture ignites the air/fuel mixture in the cylinder.