GEAR 3T8757 - Caterpillar

Probable Causes
Incorrect air/fuel ratio
Fuel supply
Intake manifold air temperature sensor
Intake manifold pressure sensor
Throttle valve differential pressure sensor
Nitrous oxide sensor
Air filter restriction
Ignition SystemRecommended Actions
Incorrect Air/Fuel Ratio
An air/fuel mixture that is too lean will have an adverse effect on engine operation. Verify that the exhaust emissions are correct. Confirm that the sensor calibration for the NOX sensor is correct. Refer to Troubleshooting, "Nitrogen Oxide Sensor - Calibrate".A change in the fuel energy content will change the air/fuel ratio. Obtain a fuel analysis for the fuel supply.If the fuel analysis is as expected, inspect the NOX sensor port in the flower pot for plugging. If necessary, clean the port. If the problem persists, refer to Troubleshooting, "Detonation Occurrence".The fuel supply pressure must be 876 to 1289 mbar absolute or 12.705 to 18.695 PSI. The gas differential pressure (delta-p) should be between 69 and 345 mbar. Delta-p below this range is allowed during cranking and idle conditions, but accuracy of the valve will be reduced. For delta-p above 276 mbar, flow accuracy will also decrease, and a reduction in valve stability may occur. Minimum proof pressure for the fuel metering valve is 0.52 bar gauge. Minimum burst pressure for the fuel metering valve is 1.72 bar gauge. Inspect the fuel lines and fuel metering valve for debris or moisture buildup.Intake Manifold Air Temperature Sensor
An intake manifold air temperature sensor that is producing an incorrect signal will have an adverse effect on the air/fuel ratio. Verify that the sensor is producing the correct signal. Measure the temperature of the intake manifold air with a thermometer. Compare the reading with the value that is displayed on the Caterpillar Electronic Technician (ET). Replace the sensor, if necessary.Note: Be sure to use an accurate thermometer for your measurements. Use of gauges that are not properly calibrated can lead to an improper diagnosis of the problem.Intake Manifold Pressure Sensor
An intake manifold pressure sensor that is producing an incorrect signal will have an adverse effect on the air/fuel ratio. Verify that the sensor is producing the correct signal. Measure the intake manifold pressure with a gauge. Compare the reading with the value that is displayed on Cat ET. Replace the sensor, if necessary.Note: Be sure to use an accurate gauge for your measurements. Use of gauges that are not properly calibrated can lead to an improper diagnosis of the problem.Throttle Valve Differential Pressure Sensor
Verify that the throttle valve differential pressure sensor is producing the correct signal. Use a 1U-5470 Engine Pressure Gp to measure the throttle valve differential pressure. Compare the reading with the value that is displayed on Cat ET. Replace the sensor, if necessary.Nitrous Oxide Sensor
Inspect the nitrous oxide sensor port in the exhaust adapter for blockage. Remove any blockage and reinstall the sensor.Air Filter Restriction
Check the air filter restriction gauge if equipped.Ignition System
Inspect the ignition transformers for the following conditions: loose connections, moisture, short circuits and open circuits. Inspect the primary wiring and the secondary electrical connections.Ensure that the correct transformers and spark plugs are