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Diagnostic Procedure

WARNING: This page is about a different car, the 2005 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.
DIAGNOSTIC PROCEDURES - LACK OF ENGINE POWER

TEST ACTION APPLICABILITY
1
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 (1600 BAR). USE EXTREME CAUTION WHEN INSPECTING FOR HIGH-PRESSURE FUEL LEAKS.
WARNING: FUEL UNDER THIS AMOUNT OF PRESSURE CAN PENETRATE SKIN CAUSING PERSONAL INJURY OR DEATH. INSPECT FOR HIGH-PRESSURE FUEL LEAKS WITH A SHEET OF CARDBOARD. WEAR SAFETY GOGGLES AND ADEQUATE PROTECTIVE CLOTHING WHEN SERVICING FUEL SYSTEM.
Turn the ignition on.With the DRBIII®, read the ECM DTCs.Are there any DTCs present?Yes --> Refer to appropriate test for problems related to this DTC.Perform ROAD TEST VERIFICATION - VER-2 .No --> Go To 2		 All
2 Turn the ignition on.
NOTE: This test requires two people. One person to test drive the vehicle while a technician observes the DRB readings

With the DRBIII® in Sensors, read and compare the Boost Pressure (PSI) with the Boost Pressure Desired/SET-POINT (PSI) while test driving the vehicle under various load conditions such as idle, hard acceleration, cruise and deceleration.
NOTE: The Boost Pressure reading should follow (trail) closely to the Boost Pressure Desired/SET-POINT reading.

Does the Boost Pressure reading follow closely to the Boost Pressure Desired/SET-POINT reading?
Yes --> Go To 3
No --> Go To 15		 All
3 Refer to the CHECKING THE ECM POWER AND GROUND TEST .
Were any problem found with the ECM powers and grounds?
Yes --> Repair as necessary.
Perform ROAD TEST VERIFICATION - VER-2 .
No --> Go To 4		 All
4 Turn the ignition on.
NOTE: This test requires two people. One person to test drive the vehicle while a technician observes the DRB readings

With the DRBIII® in Sensors, read and compare the Fuel Pressure (PSI) with the Fuel Pressure Desired/SET-POINT (PSI) while test driving the vehicle under various load conditions such as idle, hard acceleration, cruise and deceleration.
NOTE: The Fuel Pressure reading should follow (trail) closely to the Fuel Pressure Desired/SET-POINT reading.

Does the Fuel Pressure reading follow closely to the Fuel Pressure Desired/SET-POINT reading?
Yes --> Go To 5
No --> Go To 7		 All
5 Turn the ignition on.
With the DRB, select Engine, System Tests and perform the following tests:
  • Injector Fuel Correction Test.
  • Cylinder Balance test.
  • Compression Test.

Were any problems found?
Yes --> Diagnose and/or repair as necessary.
Perform ROAD TEST VERIFICATION - VER-2 .
No --> Go To 6		 All
6
NOTE: Mixing any other fuels such as gasoline or kerosine can cause this DTC to set.
Turn the ignition off.
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 (1600 BAR). USE EXTREME CAUTION WHEN INSPECTING FOR HIGH-PRESSURE FUEL LEAKS.
WARNING: FUEL UNDER THIS AMOUNT OF PRESSURE CAN PENETRATE SKIN CAUSING PERSONAL INJURY OR DEATH. INSPECT FOR HIGH-PRESSURE FUEL LEAKS WITH A SHEET OF CARDBOARD. WEAR SAFETY GOGGLES AND ADEQUATE PROTECTIVE CLOTHING WHEN SERVICING FUEL SYSTEM.
Inspect the fuel system for contamination.Is the fuel contaminated?Yes --> Repair as necessary in accordance with the Service Information.Perform ROAD TEST VERIFICATION - VER-2 .No --> Test Complete.		 All
7 Turn the ignition off.
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 (1600 BAR). USE EXTREME CAUTION WHEN INSPECTING FOR HIGH-PRESSURE FUEL LEAKS.
WARNING: FUEL UNDER THIS AMOUNT OF PRESSURE CAN PENETRATE SKIN CAUSING PERSONAL INJURY OR DEATH. INSPECT FOR HIGH-PRESSURE FUEL LEAKS WITH A SHEET OF CARDBOARD. WEAR SAFETY GOGGLES AND ADEQUATE PROTECTIVE CLOTHING WHEN SERVICING FUEL SYSTEM.

Inspect the entire fuel system for leakage.
Is there any evidence of leakage?
Yes --> Repair as necessary in accordance with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2 .
No --> Go To 8		 All
8 Refer to the appropriate Service Information and refer to Diagnosis and Testing Fuel Delivery System table.
NOTE: The following is a list of problems that can cause fuel pressure to deviate from specification: restricted fuel filter or fuel lines, failed fuel pressure solenoid, air in fuel system, failed fuel sending unit, contaminated fuel, faulty injector.

Were there any problems with the Fuel Delivery System?
Yes --> Repair as necessary in accordance with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2 .
No --> Go To 9		 All
9 Start the engine.
With the DRBIII® in Sensors, compare the Fuel Pressure SET-POINT with the Actual Fuel Pressure readings.
NOTE: If there is air in the fuel system, the Actual Fuel Pressure will oscillate above and below the Fuel Pressure SET-POINT.

Does Actual Fuel Pressure oscillate above and below the Fuel Pressure SET-POINT?
Yes --> Refer to the Service Information to purge air from the fuel system.
Perform ROAD TEST VERIFICATION - VER-2 .
No --> Go To 10		 All
10 Start the engine.
With the DRBIII® in Sensors, compare the Fuel Pressure SET-POINT with the Actual
Fuel Pressure readings.
NOTE: A sticking Fuel Pressure Solenoid is indicated by Actual Fuel Pressure gradually dropping below the Fuel Pressure SET-POINT then suddenly increasing (spiking) above the Fuel Pressure SET-POINT.

Does Actual Fuel Pressure gradually decrease then suddenly increase (spike) above the Fuel Pressure
Yes --> Replace the Fuel Pressure Solenoid in accordance with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2 .
No --> Go To 11		 All
11
NOTE: An injector that sticks open can cause this symptom. A sticking injector will cause the engine to miss fire and emit excessive black smoke from the exhaust system.
Start and idle the engine.Does the engine exhibit the symptoms described in the above note?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 ROAD TEST VERIFICATION - VER-2 .No --> Go To 12		 All
12 Refer to 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 --> Repair as necessary.
Perform ROAD TEST VERIFICATION - VER-2 .
No --> Go To 13		 All
13 Turn the ignition off.
Replace the Fuel Pressure Solenoid in accordance with the Service Information.
Turn the ignition on.
With the DRBIII®, erase the ECM DTCs.
Attempt to start and test drive the vehicle.
With the DRBIII®, read the ECM DTCs.
Does the ECM display this DTC?
Yes --> Go To 14
No --> Test Complete.		 All
14 Turn the ignition off.
Replace the Fuel Quantity Solenoid in accordance with the Service Information.
Turn the ignition on.
With the DRBIII®, erase the ECM DTCs.
Attempt to start and test drive the vehicle.
With the DRBIII®, read the ECM DTCs.
Did this DTC set again?
Yes --> Replace the Fuel Pump in accordance with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2 .
No --> Test Complete.		 All
15
NOTE: Inspect all air intake and turbocharger related tubes for damage, restriction or poor connection. Any of these conditions can cause a poor performance/lack of power symptom.
Turn the ignition off.Remove the Inlet Pressure Sensor.Connect smoke machine 84-04 to the Inlet Pressure Sensor port in the intake duct and begin injecting smoke into the intake system.Observe all intake system components for evidence of smoke leakage.Is there evidence of smoke leakage?Yes --> Repair or replace as necessary.Perform ROAD TEST VERIFICATION - VER-2 .No --> Go To 16		 All
16 Refer to Symptom List: P0234-BOOST PRESSURE SENSOR NEGATIVE DEVIATION; P0299-BOOST PRESSURE SENSOR POSITIVE DEVIATION .
Is the boost control vacuum supply system OK.?
Yes --> Using the Service Information, replace the Turbocharger assembly.
Perform ROAD TEST VERIFICATION - VER-2 .
No --> Repair boost system vacuum supply as necessary.
Perform ROAD TEST VERIFICATION - VER-2 .		 All
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