6.0L Ford Power Stroke Engine Misfire Diagnostic P0300

6.0L Ford Power Stroke Engine Misfire Diagnostic P0300
Working on a 2005 Ford F-350 Super Duty with a 6.0-liter diesel engine and we have a cylinder 7 misfire. The first thing we did is did a cylinder balance test to make sure that it was, in fact, the seven-cylinder that was in fact misfiring and it was.

Second, we made sure that injection pressure regulator was functioning properly at 85% when it was cranking. We also checked our injection pulse width. Cranking should be between .5 and 2.0 milliseconds. We also made sure the fuel injection control module Maine Power stayed above 45 volts when we were cranking the engine. Everything checked out good on the scan tool so we proceeded by doing a cylinder compression test. Providing that test about 350 PSI we’re going to go ahead and put a fuel injector in this vehicle.

527532
Vehicle Application:
2004 F-250 Super Duty 6.0
2004 F-350 Super Duty 6.0
2004 F-450 Super Duty 6.0
2004 F-550 Super Duty 6.0
Customer Concern: The engine is very hard to start when cold and then runs rough or misfires almost until it reaches operating temperature. When it came in, it had misfire codes P0300, and P0301-P0307.
Average Reported Mileage: 151938
Tests/Procedures: 1. Verify the fuel pressure is 45-60 PSI when the truck is hard to start and running rough.

2. If the fuel pressure is OK, monitor the Injection Control Pressure (ICP) reading when cranking the engine. Compare the ICP reading to the ICP Desired (ICP DSD) reading. These should match when cranking. Also, the Injection Pressure Regulator (IPR) command should not go to 85%. If the ICP does not match the DSD and the Injection Pressure Regulator (IPR) goes to 85% when cranking, address the ICP system problem.

3. If the ICP and fuel pressure are OK, monitor the fuel pulse width when cranking. It should be roughly 0.5-2.0 ms (or 500-2000 us or microseconds).

4. If the fuel pressure, ICP, and fuel pulse width are all OK check compression on several cylinders to make sure it’s at least 350 PSI. If the compression is low, address the engine mechanical problem.

5. If all OK but there is little or no smoke when cranking and hard to start, suspect injectors that are not working as they should. If it has not been done, have the Fuel Injection Control Module (FICM) reflashed per TSBs 07-5-4, 09-7-11, and 09-24-3 and recheck operation. If the updates have been done, monitor the Fuel Injection Control Module Main Power (FICM_MPWR) reading when cranking. This should stay above 45 V. If it drops, check the powers and grounds to the FICM. If the powers and grounds are OK but the MPWR is dropping, suspect a faulty voltage converter in the FICM. Replace the FICM as needed and recheck operation. NOTE, if the FICM is replaced it will normally need to be programmed for the engine to start.

6. If the FICM MPWR is OK along with all other things mentioned above, suspect sticking fuel injectors.

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