F350 6.0 Diesel misfire

John Owner Huntington Beach, California Posted   Latest   Edited  
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2005 Ford F-350 Super Duty Lariat 6.0L (P) 6-spd (S6-650) — 1FTWW31P25EC13242
P0304 — Cylinder 4 Misfire Detected

1FTWW31P25EC…,000 miles on the odometer

Need diagnostic help with this one team. Andy our lead Diesel tech is stumped

2005 F350 6.0 Diesel with rough idle #4 cylinder misfire.

Have already replaced injectors with OE reman and replaced the injector harness. Now runs worse.

Replaced the fuel injection control module and no help. Looking for ideas.

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Jacob Diagnostician
Sandy, Utah
Jacob Default
 

Were any tests done? My first step on a diesel misfire is a relative compression test.

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Michael Business Development Manager
Las Vegas, Nevada
Michael Default
 

have yo checked the EGR to see if it is clean?

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John Owner
Huntington Beach, California
John Default
 

No codes Injector buss test routed out #4 injector. Replaced all with OE Reman plus harness due to mileage. This symptom is random and usually only at idle. IDS test is next for relative compression, Generic scan with Snap On, relative comp test was normal. EGR is not clean but is not in play at idle.

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Mike Instructor
Fresno, California
Mike Default
 

Please post a capture of the IDS Power Balance when the issue occurs.

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Michael Diagnostician
Champaign, Illinois
Michael Default
 

Hi John I would put a pressure transducer or piezo sensor in the exhaust, intake, then starter current. Next synch off a Injector using current. You will have to disable fuel somehow or you could disconnect all the injectors and just plug one injector in but use one of the injectors you took out already and plug it in and secure it. Then crank the engine over and see if you notice anything…

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Randy Diagnostician
Glendora, California
Randy Default
 

hi Mike he said runs worse after injector replacement . so a good base point is to see if all injectors are working right ?? . do not u some new Never Ever Works is good . Get back to the original test point #4 . it is a ford do a koer test with scan tool and see what current ramp is when running to see what injectors health is . and then do your test . just my observation. thanks Randy

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Michael Diagnostician
Champaign, Illinois
Michael Default
 

I understand where your coming from Randy and yes it is likely that he got some junk injectors however when I get into a predicament like this I like to verify the problem. In this case making sure that it still is no 4 and not another cylinder or for that matter another issue entirely. In these situations I like to rule out mechanical with a scope and make sure the scan tool isn't lying to me…

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Randy Diagnostician
Glendora, California
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Mike john has not replied back . butt i see were you are going with this . mechanical check has already been suggested to him . i guess we what for his post

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Matt Educator
North Canton, Ohio
Matt Default
 

I would check compression if you haven't done that yet, relative or gauge before going any further

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Jay Technician
Flowery Branch, Georgia
Jay Default
 

If you have an IDS Start with a relative compression test

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Richard Technician
Stony Brook, New York
Richard Default
 

Hi John, are there any codes? Like the others mentioned I would start first with relative compression. If it looks good, make sure the connectors are correctly installed on the FICM. I would also run a buzz test to get a little direction. I see you replaced the injector harness, is it perhaps routed wrong or damaged where they plug onto the injectors.

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Brian Diagnostician
Preston, Idaho
Brian Default
 

Did you replace or reuse the old injector sealing washers? I've seen people reuse old ones and it would run worse when they finished the job. Also, like everybody else already said, check compression.

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Scott Owner/Technician
Troy, Missouri
Scott Default
 

Bad injector possibly. We went through 3 sets one time. Swap it with another cylinder if possible. Assuming relative compression and valve movement is the same. Make sure EGR is not stuck.

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Karl Educator
Milford, Nebraska
Karl Default
 

Have you checked fuel pressure and fuel aeration? It only misfires #4 at idle?

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Michael Business Development Manager
Las Vegas, Nevada
Michael Default
 

fuel aeration? How about fuel cavitation too?

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Don Owner/Technician
Big Rapids, Michigan
Don Default
 

In addition to everything already mentioned - relative compression, etc. With the IDS power balance screen running - wiggle the harness from FICM to engine. We have seen some harness rub through issues.

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Josh Technician
Lynchburg, Virginia
Josh Default
 

Wonder if you could also look at the opening coil current or voltage with the relative compression just to be sure it looks to be firing at the correct time.

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Randy Diagnostician
Glendora, California
Randy Default
 

Did you current ramp injectors

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