This article details the diagnostic process used to troubleshoot a rough running 2006 Ford F250 6.0L Powerstroke diesel engine. The owner, utilizing an AutoEnginuity scan tool and referencing Diesel Tech Ron’s expertise, systematically eliminates potential causes. This case study focuses on understanding and resolving persistent P0264 and P0266 diagnostic trouble codes (DTCs).
Pinpointing the Problem: P0264 and P0266 Codes
The truck exhibits rough starting, idling, and running conditions, coupled with a significant lack of power, especially when cold. Using an AutoEnginuity Proline VCI with Ford Enhanced Option Software and a ScanGauge II, the owner consistently retrieves the following DTCs after clearing them:
- P0264: Cylinder 2 Injector Circuit Low
- P0266: Cylinder 2 Injector Circuit Contribution/Balance Fault
Previously resolved codes related to glow plugs (P0675 and P0677) were addressed by replacing the passenger side glow plugs and harness with Motorcraft parts.
Diagnostic Steps Taken
Several tests and checks were performed to isolate the root cause:
- Battery Test: New batteries installed and load tested, ruling out low voltage issues.
- Buzz Test: Indicates a potential problem with the #2 injector, characterized by an irregular clicking pattern.
- Contribution Test: Performed using AutoEnginuity, but the results were inconclusive and difficult to interpret compared to Diesel Tech Ron’s demonstrations using the Ford IDS system.
- KOEO (Key On Engine Off) Test: Passed.
- Glow Plug Test: Passed, confirming the previous glow plug replacement was successful.
- KOER (Key On Engine Running) Test: P0264 code present.
- FICM (Fuel Injection Control Module) Voltage: Consistently above 48V in all operating conditions, seemingly eliminating FICM voltage as a culprit.
- Fuel Pressure: 60 PSI at Wide Open Throttle (WOT), measured at the fuel filter cap.
- Fuel and Oil Filters: Regularly replaced with Motorcraft filters.
- Oil Changes: Performed with 5w40 Rotella T6.
Following a 6.0L Powerstroke specific pinpoint test procedure for misfires, the owner performed the following:
- Injector Resistance Test: #2 injector resistance measured within acceptable range (0.6-0.7 ohms).
- Injector Short Circuit Test: No shorts detected.
- Injector Circuit Continuity Test: Continuity confirmed between the injector harness and the FICM connectors.
FICM Suspicions and Seeking Further Guidance
Based on the pinpoint test results, the documentation suggests inspecting the FICM connectors for damage and replacing the FICM if necessary. The owner removed the FICM (which is a remanufactured unit) for inspection and potential repair.
Drawing upon Diesel Tech Ron’s knowledge, the owner questions if a seemingly functional FICM with normal voltage readings could still have a faulty driver affecting only a single injector. The lack of a spare injector prevents further buzz test comparison. The primary concern is whether resolving the P0264 injector circuit low code will inherently address the P0266 contribution/balance fault code. Is the #2 injector not firing due to a lack of signal from the FICM?
Conclusion: Is the FICM the Culprit?
This detailed troubleshooting process highlights the complexities of diagnosing 6.0L Powerstroke engine issues. Despite seemingly normal FICM voltage, the persistent P0264 and P0266 codes, coupled with the buzz test results, strongly suggest a problem centered around the #2 injector circuit. The question remains: Is a faulty FICM driver the root cause, or is there another underlying issue affecting the injector circuit? Further investigation, potentially involving FICM testing or replacement, is required to definitively resolve the problem.
