I have lurked around this forum for a while and have been impressed by the knowledge of everybody here. This is my second 6.0 powerstroke and I have always been able to use the search function in the past to alleviate my problems. I am currently in a little bit different situation, as I have moved to a different area to start a business which requires constant use of my truck. Also, as you may guess I would like to spend as little money as possible, but as I am relying on this, would like to do it correctly the first time and not keep going back to the issues.

That being said, the main issue is as follows:
At 55 mph, as soon as the truck shifts and drops down to 1,500 rpm, it has a very rough running issue. It almost feels like the truck is bouncing. This issue first started at 122,000 miles and since then I have replaced both fuel filters, as well as the fuel water separator on the FASS fuel pump. The FASS is disconnected, but may need to be hooked up as my feelings have been that this may be a fuel related issue. There was water in the fuel at the first change, so I changed all of the filters again after running out the first tank of fuel and did not see any water. I took the truck to a transmission shop thinking that it was the OD gear and they rebuilt the transmission with a HD clutch kit and sent me on my way. There were shavings in the transmission so I was hopeful that this would fix the problem. Unfortunately, however same issue at the same speed. The shifting is much smoother throughout, however so not going to complain about an improper diagnosis. I took it to a diesel shop in Wilmington, NC and they could not recreate the issue, however I seem to see it almost every day. I thought maybe it had to do with the truck being warm by the time I drove it to their shop, but it still reoccurred after a 300 mile trip when I got off the highway onto a 55mph road. I ran my scanner and pulled the following codes:
P006A
P0275
P0276
P0401
P0404
P0405
P123B
This was after quite a few long trips, so not sure what happened when, however I did replace the number 5 injector not long ago. (Got that code before and thought it was an injector problem)

I know that my deltas between oil and water are pretty high (15-25* depending on load) and will probably need to do a coolant flush as well as oil cooler replacement, but do not think that this is related to current issue. If I need to tear down I will replace all at once, but do not know how to test fuel pump, rails, oil pump, etc which I think would be a very likely culprit. Oil just changed and looked good (no water in oil) did not check coolant as I don't think oil in the coolant would cause this type of running issue but I may be mistaken. My gut says FICM, oil or fuel pump, or rails but don't know how to test these items. Any advise would be great, as I need to keep running it until I have a game plan to knock everything out within a day or two. I can't afford to not run the truck but at the same time I don't want to end up needing to replace it. Thanks in advance for your help.

 

The first thing you need to do is get some gauges that read live data, like scan gauge II or one of the smartphone apps like dashboss for IOS devices or torque pro for android or my personal favorite Edge Insight CTS as it is necessary to have live data in diagnosing the 6.0L.
Secondly what year of truck are we dealing with and what mods have been done to it including any tunes that may be on it.

 

Sorry, it is a 2004 f350 6.0 with 144k miles and I do have scanguage II as well as Boost and EGT gauge pods. SG2 reading EOT, ECT, FMV and avg fuel while driving. I have a Bully Dog tuner which gave me the codes on tow/economy mode.

 

What's your FICM logic power showing? I'm guessing FICM or a injector or two is acting up. Mine just did the exact same thing except it would do it at idle once warm as well and somewhere between 45-55 mph just after shifting into 5th. If I gave it more throttle, it would quit. I ended up pulling the injectors and replacing the copper washers along with polishing the spool valves. Runs like a champ now. Of course that doesn't mean that's your exact problem. I'm pretty sure I had some stiction along with me not torquing the injectors down enough the two weeks prior when I replaced injector orings.

 

Is your ICP sensor on the passenger side valve cover?
A couple of house cleaning items you can attend to if you haven't done so already are check the MAP hose for cracks and MAP nipple on the intake for plugging, the MAP sensor is located just above the evaporator housing on the passenger side and is connected to the passenger side of the intake manifold via a rubber hose.
The next would be to make sure the EBP sensor tube is clear, the EBP sensor on an 04 is mounted to a stud on the thermostat housing and is connected to the drivers side exhaust manifold via a steel tube, remove the sensor and run a piece of weed whacker line through the tube and into the exhaust manifold to ensure that it is clear.
The next item would be to remove the EGR valve, clean it and reinstall it, just use brake clean being sure not to get any in the top side of the valve where the electronics reside.

 

006A is MAF, do you have an aftermarket intake filter?
Hard to say if #5 injector code is current or not since you don't remember.......did you use an OEM Ford?
#6 injector code is suspect we well. These are both low circuit codes, for starters check and double check the plugs, check them with a meter. Check for chafing as well.
0401 is EGR, is yours deleted? If not, have you checked it lately?
0404 is another EGR code.
Same for 0405......
P123B is boost condition, or lack of it. Since you have a MAF code, maybe related?
Have you tried to clean the MAF sensor lately? Could also be cracked or leaking y-pipe.
Clean the IAT2 sensor clean as well. Also check the CAC boots.

 

Good pointS! I brain farted and forgot he mentioned all those codes. I love seeing your input navistarnut. It always makes sense. Are you a tech by chance?

 

Thank you guys for the feedback so far. EGR has been cleaned about 8k miles ago. The #5 injector code is new since the new injector, but not sure at what point since then it came up. I have been moving and have not monitored well the last 3k miles I have driven, but did just change the oil and run a scan which showed the codes I stated earlier. I have a stock air filter which was changed at the time of fuel filters. Have not checked sensors. I cleared current codes, will try to do some simple cleaning and report back. FICM power I think is 49 so thought that looked good.

Sounds like some simple cleaning and checking is in need before moving further toward diagnosing. You guys have provided a lot of helpful insight. Hopefully we can get this thing squared away.

 

Heavens no I am not a tech or I would't have ended up here asking techs questions
I'm just glad there are guys here willing to answer our questions!
I do enjoy looking up codes and then posting back some things to check on, it's good review for me since the odds are I will be asking these questions at some point!

 

So no good news as of yet. Cleaned the MAF sensor today as well as checked all of the CAC boots and did not see any leaks. There were maybe a few drops of oil outside of the turbo at the hot side, but did not think anything of it as the amount was so minuscule and it is right next to the oil filter which just got replaced. More than likely spilled I THINK because no visible leaks. While cleaning the MAF sensor, however, I noticed that there was excessive corrosion on the Filter Minder connection and there was a crack at the connection boot. I am thinking this may have caused a code but please correct me if I am wrong. I will be searching for another tomorrow morning.

On another note, a weird occurrence today. In trying to eliminate additional variables, I deactivated my tuner this morning. Put it all back to "stock" and went to work. Not a long drive, maybe 7 or 8 minutes (I hear sometimes it takes as many as 15 minutes to relearn the VST) put the truck in park, went inside. Bully Dog Triple Dog tuner... Around lunch time I hopped back in the truck which was around 89* temp and proceeded to roll out of the driveway. Well this particular driveway happens to put you on a highway with vehicles traveling at 55MPH. I was shocked when I had the pedal to the floor traveling a whopping 15 MPH with oncoming traffic at 55. I did not pay a whole lot of attention to the gauges for which I apologize, as I was a little bit preoccupied. I pulled back in the other side (circular driveway) and put the tunes back on the truck. I went to lunch and came back Everything seemed normal with the tunes except on the way home the rough running occured at 55 MPH.

This strange occurence was prior to me touching anything other than removing the tunes.

 

Have you had chance to check the plugs going to #5 and #6 injectors? Check for any chaffing around that area.

 

I did not see anything obvious, and also checked ICV and looks good .25 at key on and varies between .8 and 1.9 driving but I don't know that the voltage driving makes any difference. This thing just has me baffled.

 

You cleaned the EBP and EGR again? I would even though it was a few months ago. Unplug the EBP and see what happens during a test drive.

 

Sorry for discontinuing this for a bit, been pretty busy. On a side note cleaned EGR again and EBP and got somewhere around 16.7 mpg on the highway my last trip, which was about a 3mph gain. That was nice, but still having issues. I guess I will be replacing a number 5 injector after doing a compression test on the engine and will go from there. Does anybody have any recommendations while this thing is apart?