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Home >> Jeep >> 2023 >> Gladiator Freedom, Part Time T/Case Control >> Repair and Diagnosis >> Engine Performance >> System >> DRIVEABILITY - Diesel - Non-DTC Based Diagnostics >> Diagnosis And Testing >> Lack Of Engine Power >> Diagnostic Test

Diagnostic Test

  1. CHECKING ENGINE OIL LEVEL 
    1. Check that the engine oil level is correct.

      Is the oil at the correct level?

      Yes 

      • Go To  2

      No 

      • Correct the engine oil to the proper level.
      • Perform the PCM VERIFICATION TEST. Refer to PCM VERIFICATION TEST .
  2. CHECKING FOR PCM DTCS 
    1. Turn the ignition on.
    2. With the scan tool, read the PCM DTCs.

      Are there any DTCs present?

      Yes 

      • Diagnose and repair the PCM DTCs before proceeding.
      • Perform the PCM VERIFICATION TEST. Refer to PCM VERIFICATION TEST .

      No 

      • Go To  3
  3. CHECKING THE BRAKE SWITCH ADJUSTMENT 
    1. Check for proper Brake Switch adjustment.

      Is the Brake Switch adjusted correctly?

      Yes 

      • Go To  4

      No 

      • Adjust or replace the Brake Switch as necessary.
      • Perform the PCM VERIFICATION TEST. Refer to PCM VERIFICATION TEST .
  4. CHECK THE INTAKE SYSTEM 
    1. Inspect the entire Intake System, including the Intercooler for signs of a leak.

      Were any problems found with the Intake System?

      Yes 

      No 

      • Go To  5
  5. CHECK THE EGR SYSTEM 
    1. Inspect the entire EGR System for signs of a leak.
      NOTE:

      Soot streaking around the EGR Valve or system components is an indication of a leak in the EGR System.

      Were any problems found with the EGR System?

      Yes 

      No 

      • Go To  6
  6. CHECK THE EXHAUST SYSTEM FOR RESTRICTIONS 
    1. Visually inspect the exhaust system for signs of damage which could cause restrictions.

      Were any problems found with the exhaust system?

      Yes 

      No 

      • Go To  7
  7. COMPARE THE FUEL PRESSURE ACTUAL READING AGAINST FUEL PRESSURE SET POINT 
    NOTE:

    This test requires two people. One person to test drive the vehicle while a technician observes the scan tool readings.

    1. With the scan tool, select add the fuel rail pressure to a graph.
    2. With the scan tool, select add the fuel rail pressure setpoint to a graph.
    3. Select merge graphs.
    4. With the scan tool, compare the Fuel Pressure Actual reading with the Fuel Pressure Setpoint on the graph, while cranking the engine on a no start, or while test driving the vehicle under various load conditions such as idle, hard acceleration, cruise and deceleration.
      NOTE:

      The Fuel Pressure reading should closely follow the Fuel Pressure Setpoint reading.

      Does the Actual Fuel Pressure reading follow the Fuel Pressure Desired/Setpoint reading?

      Yes 

      • Go To  8

      No 

  8. FUEL INJECTOR 
    WARNING:

    High Pressure fuel lines deliver diesel fuel under extreme pressure from the injection pump to the fuel injectors. This may be as high as 23, 200 PSI (1600BAR). Use extreme caution when inspecting for high pressure fuel leaks. Failure to follow these instructions may result in possible serious or fatal injury.

    WARNING:

    Fuel under this amount of pressure can penetrate skin causing possible serious or fatal injury. Inspect for high pressure fuel leaks with a sheet of cardboard. Wear safety goggles and adequate protective clothing when servicing fuel system. Failure to follow these instructions may result in possible serious or fatal injury.

    NOTE:

    An injector that sticks open can cause this symptom. A sticking injector will cause the engine to misfire and emit excessive black smoke from the exhaust system.

    1. Start and idle the engine.
    2. With the scan tool, perform the Cylinder Fuel Quantity Correction Test.
      NOTE:

      A problem injector will be indicated by a significant change in correction quantity as compared to the rest of the injectors.

      Are any of the injectors displaying a significant amount of injection quantity correction?

      Yes 

      • Using the service information, remove and inspect the Fuel Injectors for signs of damage or debris that may cause the injector to stick. Sticking injectors may cause the combustion chamber to become black and oil soaked. Replace Injector(s) as necessary.
      • Perform the PCM VERIFICATION TEST. Refer to PCM VERIFICATION TEST .

      No 

      • Go To  9
  9. CHECKING BOOST PRESSURE 
    1. Turn the ignition on.
      NOTE:

      This test requires two people. One person to test drive the vehicle while a technician observes the scan tool readings.

    2. With the scan tool in Sensors, read and compare the Boost Pressure (PSI) with the Boost Pressure Desired/Setpoint (PSI) while test driving the vehicle under various load conditions such as idle, hard acceleration, and cruise.
      NOTE:

      The Boost Pressure reading should directionally follow (trail) the Boost Pressure Desired/Setpoint reading.

      Does the Boost Pressure reading follow the Boost Pressure Desired/Setpoint reading?

      Yes 

      • Go To  10

      No 

      • Check the vacuum supply lines and Turbocharger Actuator operation. If any problems are found, repair as necessary. If no problems are found, replace the Turbocharger.
      • Perform the PCM VERIFICATION TEST. Refer to PCM VERIFICATION TEST .
  10. ENGINE DRIVE BELT/CHAIN 
    1. Use the service information to ensure the Engine Drive Belt/Chain is installed correctly and the camshaft and crankshaft gears are timed correctly.

      Were any problems found?

      Yes 

      No 

      • Test Complete.
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