3176C, 3406E and 3456 Industrial Engines Troubleshooting – Exhaust Has Excessive Black Smoke

Probable Causes


  • Air inlet or exhaust system 
  • Engine speed/timing sensors 
  • Atmospheric pressure sensor 
  • “Turbocharger outlet (boost) pressure sensor” 
  • “Fuel Position” and/or “FRC Fuel Limit” 
  • Flash file 
  • Fuel quality 
  • Valve adjustment 

Recommended Actions

Air Inlet or Exhaust System


  1. Check the air inlet system for restrictions and for leaks. 
    1. Check for an air filter restriction.


    1. Perform a visual inspection of the air inlet piping for restrictions and for leaks.


  1. Ensure that the turbocharger is in good repair.


  1. Check the exhaust system for restrictions.


  1. Repair any leaks that were found. Remove any restrictions that were found. Replace any damaged components.

Engine Speed/Timing Sensors


  1. Check the calibration of the engine speed/timing sensors. Refer to Troubleshooting, “Timing – Calibrate”.


  1. Verify that the crankshaft and the camshaft drive gears are set with the proper orientation. Refer to the Disassembly and Assembly manual.

Atmospheric Pressure Sensor

Check the atmospheric pressure sensor for dirt and/or for debris. Remove any dirt and/or debris that is present. The correct reading for the atmospheric pressure is between 50 kPa (7.25 psi) and 100 kPa (14.5 psi).

“Turbocharger Outlet (Boost) Pressure Sensor”, “Fuel Position”, and/or “FRC Fuel Limit”


  1. Monitor the status of “Fuel Position” and “Rated Fuel Limit” while the engine is operating under full load. If “Fuel Position” equals “Rated Fuel Limit” and “Fuel Position” is less than “FRC Fuel Limit”, the Electronic Control Module (ECM) is providing the correct control. Otherwise, proceed to the next Step.


  1. Verify that there are no active diagnostic codes for the intake manifold pressure sensor.


  1. Monitor the status of “Turbocharger Outlet (Boost) Pressure” and “Atmospheric Pressure” on Caterpillar Electronic Technician (ET). When the engine is not running, “Turbocharger Outlet (Boost) Pressure” should be 0 kPa (0 psi).Note: A problem with the “FRC Fuel Limit” will only cause black smoke during acceleration. A problem with the “FRC Fuel Limit” will not cause black smoke during steady state operation.

Flash File

Verify that the correct flash file is installed in the ECM. Refer to Troubleshooting, “ECM Software – Install” for information.

Fuel Quality

Cold weather adversely affects the characteristics of the fuel. Refer to Operation and Maintenance Manual for information on improving the characteristics of the fuel during cold weather operation.

Valve Adjustment

Check for the correct valve adjustment. Refer to Systems Operation/Testing and Adjusting for information on adjustment of the valves.

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