G3520B Industrial Engines Caterpillar

The Electronic Control Module (ECM) provides control of the air/fuel mixture for maximum performance and for efficiency at low emission levels. The system consists of the following components: maps in the ECM, output drivers in the ECM, sensors and customer's input via the Caterpillar Electronic Technician (ET). The ECM compensates for changes in the BTU of the fuel in order to maintain desired emission levels. Illustration 1 is a diagram of the system's main components.

Illustration 1	g01456978
Diagram of the system for the air/fuel ratio control

To accurately control the air/fuel ratio, the ECM depends on the following parameters that are programmed via the "Configuration" screen of Cat ET. For details on these parameters, refer to Systems Operation/Testing and Adjusting, "Electronic Control System Parameters".

• "Emissions Feedback Mode configuration"

• "Desired Engine Exhaust NOx Level Setting"

• "Air/Fuel Proportional Gain"

• "Air/Fuel Integral Gain"