2007/10/01 Caterpillar

Engine:

G3508 (S/N: WPN1-UP)

G3512 (S/N: WPP1-UP; WPR1-UP)

G3516 (S/N: WPT1-UP; WPW1-UP)

New Series G3512 and Series G3516 Engines now meet the new emissions ratings that are set by the US Environmental Protection Agency (EPA) Spark Ignited Stationary New Source Performance Standards (NSPS).

• 2 g NOx/bhp-hr

• 4 g CO/bhp-hr

• 1 g NMHC/bhp-hr

The Series G3512 and Series G3516 NSPS Engines have a new emissions control system that uses a NOx sensor in the exhaust stream. This NOx sensor replaces the oxygen sensors in previous engines. The strategy for the control of the emissions that uses the NOx sensor is simpler. The strategy for the control of the emissions is based upon the direct measurement of oxides of nitrogen in the exhaust. The simplicity and the direct measurement of NOx has enabled Caterpillar to narrow the variation of NOx emissions in order to provide engine operation within the EPA limit of 2 g NOx/bhp-hr.

Note: Note: For more detailed information on NSPS, refer to Product News, LEXW6413.

This new control strategy requires Caterpillar Electronic Technician (ET) version 2007B or newer versions in order to adjust the control strategy for the air/fuel mixture and for emissions. Earlier versions of Cat ET are not capable of performing these functions with the engine Electronic Control Module (ECM).

The NOx sensor is located directly to the rear of the exhaust elbow, which is the same location as the oxygen sensor that is used in previous engines.

The sensor is hard-wired to a buffer module. The design of the 309-4209 NOx Sensor Gp forms a single serviceable component.

The engine wiring harness has been changed to incorporate a mating connector for this new sensor group.

The bypass plate for the fuel valve has been updated in order to improve the accuracy of the fuel valves control and to improve the ability to tune the fuel valve. The recommendation for operation at the rated speed and the rated load is to set the fuel valve at 80 percent open with a fuel correction factor (FCF) of 100 percent. Refer to Table 1

Illustration 1	g01402794
Rear view (1) NOx sensor (2) Connector (3) Buffer