Section B - Engine Surges at Idle

Perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

1. DTC / Product Improvement: Check for any service bulletins related to the customer's concern or Diagnostic Trouble Codes (DTC's) present. Follow appropriate guidelines in the diagnostic procedures outlined in TechCONNECT. Is the vehicle repaired?

a. Yes >> Go to Step # 15.

b. No >> Go to Step # 2.

2. Verify complaint: Verify proper fuel quality, grade, and level in the fuel tank. Operate the engine at idle speed. Using the appropriate scan tool, log the fuel pressure set point and actual fuel pressure. A good system will have actual fuel pressure that is +/- 500 PSI from the set pressure. (Example: If the fuel pressure set point at idle is 6500 PSI, the actual fuel pressure on a good system is expected to be between 6000 - 7000 PSI). If fuel pressure variation is excessive, an audible surge will be present. If the variation is severe, a slight engine speed variation may also be noticed. Does the actual fuel rail pressure fluctuate more than +/- 500 PSI?

a. Yes >> Go to Step # 3.

b. No >> Go to Step # 8.

NOTE:
A loud "knock" and black smoke that exists with an actual fuel pressure drop may be an injector issue and should be identified using the single cylinder cut out test.

3. Verify proper low pressure fuel supply to the injection pump: Perform the appropriate fuel supply system flow test. NOTE: This procedure may be slightly different depending on if the vehicle has an engine mounted transfer pump or the in-tank transfer pump. In a good low pressure fuel system, fuel flow of 560 mL in 10 seconds or better is expected for model years 2003 and early 2004. The fuel volume for the model years late 2004 through 2007 is 590mL in 10 seconds. Be sure there is no air in the system. Is the low pressure fuel supply sufficient?

a. Yes >> Go to Step # 4.

b. No >> Repair the low pressure fuel supply system. Refer to the detailed diagnostic information available in TechCONNECT under: Service Info tab > 9 - Engine> Diagnosis & Testing > Fuel Lift Pump - Diesel. >> Go to Step # 15.

4. Test for high injector return flow: Refer to the detailed diagnostic information available in TechCONNECT under: Service Info tab > 9 - Engine > Diagnosis and Testing > Injector Return Flow Test. Do the injectors pass the "Injector Return Flow Test"?

a. Yes >> go to Step # 6.

b. No >> go to Step # 5.

5. If the injector return from any cylinder(s) is deemed excessive:

a. Check HPC tip for damage, replace HPC if damaged. Refer to the detailed service information available in TechCONNECT under: Service Info tab > 14 - Fuel System > Fuel Injection > Fuel Injector > Removal/Installation. >> Go to Step # 15.

b. If HPC tip is undamaged, replace the injector and HPC. Refer to the detailed service information available in TechCONNECT under: Service Info tab > 14 - Fuel System > Fuel Injection > Fuel Injector > Removal/Installation. >> Verify that a quality fuel filter is used. >> Go to Step # 15.

6. Verify high pressure pump output volume: Remove the high pressure fuel line from the high pressure pump outlet port to the fuel rail. Connect a suitable hose to the high pressure outlet port of the high pressure pump and route it to a graduated container. Disconnect the Electronic Fuel Control Actuator. Crank the engine until fuel exits the hose. NOTE: With the discharge line routed to atmosphere, fuel will discharge at 0 PSI. Crank the engine for three 10 second intervals, pausing to allow the starter to cool between each crank event. High pressure pump output volume must be greater than 70 mL in 30 seconds. Is the high pressure pump output flow sufficient?

a. Yes >> go to Step # 7.

b. No >> Replace the high pressure pump. Refer to the detailed service information available in TechCONNECT under: Service Info tab > 14 - Fuel System > Fuel Injection > Fuel Injection Pump. >> Go to Step # 15.

7. Electronic Fuel Control Actuator (FCA): Replace the Electronic Fuel Control Actuator. Refer to the detailed service information available in TechCONNECT under: Service Info tab > 14 - Fuel System > Fuel Injection > Fuel Injection Pump. >> Go to Step # 15.

8. Verify High Pressure System Is Functioning Normally: Using the appropriate scan tool watch the fuel rail pressure set point. Does the fuel rail pressure set point fluctuate at idle?

a. Yes >> Check the vehicle for signs of parasitic load causing the ECM to adjust fuel pressure set point.

b. No >> Go to Step # 9.

9. Idle speed fluctuation: Using the appropriate scan tool watch idle speed. Compare the idle speed shown on the scan tool to the reading on the tachometer. Does the idle speed on the scan tool fluctuate more than 20 RPM while the engine is at idle?

a. Yes >> Go to Step # 10.

b. No >> Investigate fuel quality. Look for evidence of fuel contamination. Investigate for aftermarket performance devices.

10. Verify proper low pressure fuel supply to the high pressure pump: Perform the appropriate fuel supply system flow test. NOTE: This procedure can be slightly different depending on if the vehicle has an engine-mounted transfer pump or the in-tank transfer pump. In a good low pressure fuel system, fuel flow of 560 mL in 10 seconds or better is expected for model year 2003 and early 2004 vehicles. In a good low pressure fuel system, fuel flow of 590 mL in 10 seconds or better is expected for late model year 2004 through 2007 vehicles. Be sure there is no air in the system.

Is the low pressure fuel supply volume sufficient?

a. Yes >> Go to Step # 11.

b. No >> Repair the low pressure fuel supply system as necessary. Vehicles equipped with an in tank fuel pump: Refer to the detailed diagnostic information available in TechCONNECT under: Service Info tab > 9 - Engine > Diagnosis & Testing > In-Tank Fuel Lift Pump Flow/Diagnostic Test Procedure. Vehicles equipped with an engine mounted fuel transfer pump: Refer to the detailed diagnostic information available in TechCONNECT under: Service Info tab > Diagnostics tab, Powertrain Gas, Driveability Diesel, Fuel Lift Pump Flow And Inlet Restriction Test >> Go to Step # 15.

11. Fuel Return: Check for kinked or restricted fuel return lines. Check the fuel tank venting. Does a fuel return system restrictions exist?

a. Yes >> Repair as necessary. Go to Step # 15.

b. No >> go to Step # 12.

12. Intake / Exhaust Systems: Check for inlet restriction, inspect air filter for excessive dirt/debris. Verify air intake tubes and hoses are not kinked or restricted. Check for charge air cooler air system leaks. Perform "INTAKE AIR SYSTEM PRESSURE TEST - DIESEL". Refer to the detailed service information available in TechCONNECT under: Service Info tab > 11 - Exhaust System > Turbocharger System > Turbocharger > Inspection. Inspect Turbocharger for excessive compressor wheel movement and proper waste gate operation. Check for exhaust restriction. Check for kinked or blocked exhaust pipes. Verify proper exhaust brake operation (if equipped). Were any issues found with the Intake/Exhaust Systems?

a. Yes >> Repair as necessary - Go to Step # 15.

b. No >> Go to Step # 13.

13. Other Vehicle Systems: Verify proper operation of the Transmission Clutch. Verify proper operation of the Transmission. Verify proper operation of the Vehicle brakes (check for dragging). Verify proper operation of the Cooling fan operation cycle time. Verify proper operation of the Engine driven accessories. Were any issues found with the Vehicle System?





a. Yes >> Repair as necessary. Go to Step # 15.

b. No >> Go to Step # 14.

14. Base Engine: Check for internal engine damage. Valve lash settings, engine compression, cylinder leak down, etc. Were any issues found with the Base Engine?

a. Yes >> Repair as necessary. Go to Step # 15.

b. No >> Go to Step # 15.

15. Repair Complete: Perform Powertrain Verification Test VER - 1 (Diesel). Refer to the detailed service information available in TechCONNECT under: Service Info tab > 8 - Electrical/Electronic Control Modules/Engine Control Module > Diagnosis And Testing.