[6LiterTeter]

Hi All. Our 2003 6.0 with 239k. Went in recently for a p0278 and an intermittent very slight rough idle. Highly skilled Master Tech used IDS to diag and determine that injectors 2 and 6 were on their way out. Replaced 2/4/6/8 injectors and ICP sensor/harness as it was leaking around the harness. Also, blue spring kit and fresh fuel filters.

All was well for 700 miles or so before two injectors on the other side started to over-fuel. P0278 triggered again. The shop owner replaced the other bank of injectors at cost, no charge for labor even though it wasn’t his fault. A stand-up thing to do in my opinion.

Driving around today and sure enough, p0278 comes back with a very slight rough idle at stoplights. Pull over, cycle key, shift to drive and slight rough idle is gone.

I’m going to be humble here and ask for a reminder of the basics. There is no blow by, no tick or rapping sound, no smoke, no signs of a mechanical failure like a rocker or lifter. No loss of power at all. Perfect FICM voltage and ICP readings. The intermittent rough idle is so very slight when it happens but I can tell its there. No loss of oil or coolant and got 21mpg on I-85 today for 14 miles with the AC on full blast.

Point me away from overthinking and toward the basics I might be overlooking. Shop owner will absolutely make it right, I’m not at all worried. Just want some opinions on what might be the issue. I’m resisting hooking up to Forscan and trying to be a mechanic for just a bit.

 

[MtnTallPaul]

I have nothing to offer other than "sounds like a good shop!"

 

[bismic]

What injectors did the shop install?

If it gets bad enough to bother you, you could have the shop switch #6 with #4 and see if the code followed the injector.

I sure would like to get 21 mpg ...............

 

[6LiterTeter]

What injectors did the shop install?

If it gets bad enough to bother you, you could have the shop switch #6 with #4 and see if the code followed the injector.

I sure would like to get 21 mpg ...............

Good suggestion. They installed all eight at this point. It’s just peculiar that this #6 cylinder contribution persists. Maybe a coincidence, maybe not. Has my wheels turning for sure.

 

[bismic]

I was just wanting to verify that they were OEM re-manufactured injectors.

 

[6LiterTeter]

I was just wanting to verify that they were OEM re-manufactured injectors.

…

Sorry, I meant to say all eight Ford injectors. No aftermarket.

 

[bismic]

I figured they were OEM, but you can get OEM in remanufactured AND in new. I don't believe Ford dealerships have the new OEMs though.

 

[Hydro]

So, same code with a different injector already -- thinking bad connection or short in the harness
Lots of places for that harness to rub thru between the injector and FICM
In case you have not already looked that code up -- it indicates a misfire on number 6 -- would have thought there would also be another code for shorted or open coil

 

[6LiterTeter]

So, same code with a different injector already -- thinking bad connection or short in the harness
Lots of places for that harness to rub thru between the injector and FICM
In case you have not already looked that code up -- it indicates a misfire on number 6 -- would have thought there would also be another code for shorted or open coil

Good thoughts. That’s what initially had me worried about a mechanical issue. But, the fact that it’s intermittent steers me back toward that harness as well.

 

[6LiterTeter]

Update on this thread.

I can’t physically swap connectors (just not enough length so…

Sam (shop owner) replaced #6 injector as part of due diligence because shop owner has seen a higher failure rate with new injectors out of the box as of late. Wiggle test and harness resistance test good.

Relative compression test perfect. Since went on to perform manual compression test. All well within spec as expected.

Installed most recent FICM software and reloaded PHP tune. No change, p0278 and slight rough idle (bobble) returns after engine warms up. Not present for the first 10 or so minutes while the engine is warming.

Circuitboard Medics is 15 minutes away so I took the FICM in for rebuild. Reinstalled and test drove but condition remains except now I’m getting slight variations in idle where it feels like engine is trying to smooth out.

Next morning, went to start truck and the injectors wouldn’t cycle. Walked away for a few minutes. Came back and all was normal.

I’m still suspecting FICM logic. Main power and logic power are normal but even the Circuitboard Medic rep was honest in that logic failures are difficult to replicate and diag. I have a message out to them currently and waiting to hear back about next steps.

To add…zero blow by, zero smoke except briefly at WOT, no inconsistent crank, no tapping, rapping or loss of power. Just a p0278 that seemingly only happens after warmup and is only noticeable at idle. Hm.

 

[bismic]

Maybe an oil leak at the ball tube seal (nipple cup seal)? Only a guess, but sounds like that is all that is left to do.

 

[6LiterTeter]

Maybe an oil leak at the ball tube seal (nipple cup seal)? Only a guess, but sounds like that is all that is left to do.

Something I haven’t thought of and didn’t think to ask Sam. Replacement seems pretty straight forward. I haven’t seen anything like that associated with cylinder contribution but it would make sense.

Edit: also might explain why it only presents itself after the engine warms up.

 

[bismic]

Clearly an injector top seal leak can cause a contribution code for that injector/cylinder, so maybe not a big leap to think that the nipple cup seal might also be able to cause one. That said, I can't say I have ever seen anyone directly connect a leak there to a single injector contribution code when everything else looked "essentially perfect".

 

[FordDoctor]

Were the oil stand pipes replaced when the injectors were done? They contain a check valve that helps reduce hydraulic noise in the oil rails especially in a 2003 engine. We have seen worn check valves and even broken stand pipes cause funky idle quality.

 

[6LiterTeter]

Were the oil stand pipes replaced when the injectors were done? They contain a check valve that helps reduce hydraulic noise in the oil rails especially in a 2003 engine. We have seen worn check valves and even broken stand pipes cause funky idle quality.

No Sir, they were not replaced. Very valuable feedback. He has nitrogen and can do some advanced testing at higher pressures as needed. I’ll talk with him and follow up.

 

[6LiterTeter]

@bismic @FordDoctor, do either of you think there would be drivability issues associated with either of those issues? Other than a slight “bobble” at idle (that bugs the crap out of me because I’m a perfectionist) there aren’t any performance concerns. In short, it pins you against the seat and is still getting outstanding fuel mileage. ICP% looks to be spot on throughout different driving scenarios. Just wanted to ask before I talk with Sam.

 

[Hydro]

Oil system leaks would cause the whole system to be down on pressure and the IPR % to be high -- if a single injector leaking on one bank, and the stand pipe check valve is bad, then just that bank would be low in pressure
A rail pressure leak would not affect only one injector

I am thinking is is likely the logic side of the FICM causing this problem -- would be good if you had a loaner you could test with

 

[bismic]

Oil system leaks would cause the whole system to be down on pressure and the IPR % to be high -- if a single injector leaking on one bank, and the stand pipe check valve is bad, then just that bank would be low in pressure
A rail pressure leak would not affect only one injector

I am thinking is is likely the logic side of the FICM causing this problem -- would be good if you had a loaner you could test with

Odd things can happen - especially in 03 engines (lol). I know that eventually the OP in the thread linked below saw other cylinders impacted, but not at first - it took a power balance test:

Repeat Cylinder Contribution Codes on same cylinders...

Hey All, I have a real head scratcher of a problem I have been wrestling with... WARNING!!! LONG STORY!!! The Back Story: I got an Edge Insight CTS in January. As the weather warmed up this spring I found my ECT/EOT Delta was right at the 15* limit when cruising @ 65 mph. I did an extensive...

www.powerstroke.org

Anyone replace oil rail check valves? - Ford Truck Enthusiasts Forums

6.0L Power Stroke Diesel - Anyone replace oil rail check valves? - Looking for any insight on replacing the check valve in the oil rail. Part number 3C3Z-6N853-BA, TSB 08-20-01 references it. Manual doesn't show anything and I'd like to know what it takes to get it out of the rail before I tear...

www.ford-trucks.com

Not frequent that a logic side issue only impacts one injector (and a contribution code at that), but it can in the early FICMs. Probably another semi long shot, but that is where we are. That said, it is a easier to try a known good FICM than to get under a valve cover (and it can be free, but only if you know someone).

Don't get over a couple hundred psi with gas checking for leaks. you can actually damage oil system seals with high pressure gas when it eventually finds a place to blow through. Gas is used because the gas viscosity, density (and lack of surface tension) will show leaks at significantly lower pressures (easily a factor of 15). Nothing good can come from testing with gas pressure over 200 psi.

 

[6LiterTeter]

Thank you everyone for the insight. Circuitboard Medics is going to run this rebuilt FICM in their truck to make sure the problem follows. I’m good with that. If it doesn’t, we will dig in further.

It is a burden to be this picky most days. Borderline obsessive.

 

[FordDoctor]

No Sir, they were not replaced. Very valuable feedback. He has nitrogen and can do some advanced testing at higher pressures as needed. I’ll talk with him and follow up.

Pressurized nitrogen is used for LEAK testing the system as it provides higher pressure than "shop air." The stand pipe check valve is a shot in the dark as finding a bad one usually requires replacing them and getting results. It's a long shot suggestion but I felt it was worth floating out there. Since I did not perform any repairs on this truck I can't say if yours are original or if they have ever been replaced however If I were to sell a set of injectors you bet you would be getting a new set of stand pipes and block off tubes... or at the very least quoted in the price for the kit if case they are needed or outdated. This has been discussed in the DTS forums - it's a rare failure as I mentioned but I have pulled out broken/cracked stand pipes and actually had ONE with a failed check valve. Had a rough idle.