Unsolvable (so far) 6.0 mystery issue
 

I am in need of some help/suggestions. I have a truck that has recently came into my shop that 2 other shops have tried to figure out and were not successful. A little background on the truck...
Its a 2005 F250.
with a 6.0 (obviously)

At the first shop the truck had a used engine put it in, the engine was out of a 2003 excursion. Everything went all fine and dandy and the truck ran perfectly fine. 3 months later the owner of the truck was driving down the interstate and the truck died and had it towed to the original shop. They found the reason behind the truck dying was due to gasoline in the fuel tank. They then drained the fuel out of the tank and flushed it and all the lines, and replaced all the filters. Truck was started back up and had a misfire and showed to have a few bad injectors, So the shop just went ahead and replaced all 8 injectors. The truck then was started back up and ran around for awhile and still had a slight misfire to it and it showed 4 injectors still being bad. So 4 more were once again replaced. Then the truck was started and driven and all seemed to be good....until the truck got warmed up, once warm the truck began to miss and surge above 2000 rpm. So it was diagnosed and the ICP and IPR were replaced but did not fix the issue. Then the HPOP was thought to be the problem so it was replaced....did not fix it......Then the shop performed a compression test and found 1 cylinder to be 15psi less than the rest, so they pulled the heads and had them tested and found one exhaust valve to be slightly leaking, head got a valve job and was put back together with studs and oe gaskets, egr delete, updated oil cooler, and a sct tuner. Truck was put back together and once again same issue, once warm it missed and surged above 2000 rpm. So then the shop thought it could be in the lift pump from gas being ran though it and replaced the lift pump, still same problem after wards. Shop then tried another ICP, IPR, ECM, FICM, Engine wiring harness, and Injector wiring harness, and afterwards still the same issue. Then they thought the problem maybe in the transmission so the trans was pulled and rebuilt with a new torque converter, still did not fix the problem. This is the point where this shop had finally given up.

One to the next shop (diesel injection), once there they pulled all injectors and cleaned them then they were put on the stand to test them, and they all tested fine. They pulled the stand pipes and checked them and they were also fine. The tried reflashing the FICM and ECM again, they also tried replacing the ICP and IPR (which would make the 3rd time)., as well as trying new ipr and icp pigtails. Still did not fix the problem. This is the point where the second shop called it quits.

And now I have the truck...
I have not drove into the truck much at all, all I have done so far was hooked up a scanner and checked a few things out. A few things have caught my eye so far...

The MAF voltage and airflow (G/S) did not move at all, come to find out after popping the hood, from the factory it did not have one (connector was there but it had a "dummy" plug plugged into it and the intake did not have a hole for the sensor). I had an intake laying around that has the MAF in it so I tried to install it and plug it in, It did not change anything still has a miss/sure above 2000rpm when warm.

The other thing I noticed while having the scanner hooked up was it looked like the ICP voltage jump around a good ammount whille steadily holding the pedal at 2000 rpm. I have not tried to dig any further into that yet.
Everything else data wise looks perfect.

So quick recap truck runs very well. Truck starts perfectly cold or warmed up. There is no loss in power and cylinder contribution looks perfect. But once the truck gets to operating temperature the truck will have a miss above 2000 rpm with or with a load on it. But even with the miss above 2000 you can push the skinny pedal and it will power through it and run perfectly fine and have plenty of power. This problem did not arise until after the truck died and the original shop found it to be full of gasoline.

All data (ICP,IPR,etc) look to be textbook perfect. Pretty much everything imaginable has already been replace once if not 2 or 3 times.

So if anyone has any suggestions/thoughts/ideas feel free to let me know..Im just thinking that maybe there is something small and simple that everyone is overlooking...but its highly unlikely that there has been 2 reputable shops that have looked at the truck and neither one so far has came up with a solution. Im just know that I dont want to get overly involved in this truck and get money tied up that I will not get back because it didnt fix it.

I know its a long post sorry, but I figured for something like this as much info as possible might give someone a clue or be useful in pointing me into the right direction on where to even begin.

We replaced maybe 2-3 engine harnesses on a few 6.0's and even some 7.3's for similar issues. I don't know what Ford or Navistar's deal is with wiring harnesses but there seems to be no end to wiring issues on these things.

In my mind I really want to start chasing wires but what throwing me off is that it doesnt start to do it until you have been driving it awhile and the engine is good and warm, which has always told me in the past that its something in the high pressure oil system but with those other 2 shops replacing damn near everything related, It seems to be a waste of time to try anything else related to that

We had a 6.4 ambulance once that would die when they would take a hard right turn, like a looping interstate on ramp. Not good with an ambulance. It went to 3 Ford dealers and then they brought it to us. Ended up being the factory wiring harness just up from where they had wired in the "ambulance" wiring. The "ambulance" wiring was too short and was pulling the factory wiring apart when the frame/body flexed in a hard right turn.

I would start with the wiring. Seems like you have replaced most, if not all the mechanical things that could be messing up, multiple times. If someone says 'bad ground' in this thread, I will personally drive to their house and scissor kick them in the face.


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Lol yeah that what I thought but what throws me off is that the engine wiring harness and injector wiring harness were both replaced twice already by the first two shops that have worked on it, and the truck doesn't have this issue until it's warm

No crank or cam sensor replacements? Just shooting from the hip, but if it was me, I'd be checking crankshaft RPM vs camshaft RPM (leaning for towards crank signal). No codes?

Electron or conventional theory? Everything is a bad "ground" eventually.

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my vote gets crank vs cam. Sensor gets hot, becomes resistive and less sensitive. Probably will even be the cam since it occurs at high speed.

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I missed that the engine harness had been replaced. Went back and re-read the OP and you did say one shop had replaced it.

I will check that tonight on my way home and report back with findings, thanks for the suggestions

If all else fails just drop an cummins in it.


I'm with the guys on the crank/cam sensor. They can get weak or get crap piled on them.

not to be a dick but all three shops need to start DIAGNOSING not guessing. this is exactly why the 6.0 gets bad reputation!!!! valve job, injector job, and trans overhaul for misfire .....Really?????? 6.0 is as about as simple as it gets on a modern diesel..... proper tools and procedures will identify problem quickly. So called" DIESEL SHOPS" give these trucks bad name . fuel pressure ? under load ? volume? quality? oil full? quality? misfire under load should be easy to identify with ids every misfire will be logged single cylinder? multiple cyl misfire? say has new injectors new oem ? or rebuilt by hillbilly bob? 05 federal trucks will not have maf if harness has takeout for iat sensor. Why are we questioning the cam and crank sensor 10 minutes with 2 channel lab scope will tell you if they are good or bad. F@ck it just throw another 100 bucks in parts maybe this will fix it.

Lol tell us how you really feel. I dont know how you can say the 6.0 is the simplest modern diesel. A CR Cummins isnt more simple? Please...

not really, I'll take gm or ford electronics over dodge anyday.

Oh, but you are....


That's it! I never realized it until you pointed this out! The problem isn't the 6.0, it's all the shops that just can't figure out how to fix them when they break that's the problem.:doh:


We are in the presence of Modern Diesel Greatness fellas....:bow:


The only thing you've said that makes any sense....


And the Greatness continues.....:bow:

LOL LOL LOL


I will give you this, the 6.0 Fords are the best thing that ever happened to our shop. We saw 2:1, probably more like 3:1, 6.0's over any Dodge, GM, or 7.3 Ford.

I agree i have made a very good living fixing 6 leakers never said they are reliable. And when ford out sold there competitors with over 400,000 units a year not surprising shops are full of them.


my entire point is Throwing parts at something isn't going to fix it. 6.0 is not complicated is has to have compression just like every engine . it has to have good fuel quality pressure and volume. It has a cam and crank sensor for engine speed like a gasser a manifold pressure sensor an exhaust back pressure sensor 4 temp sensors 1 oil , 1 coolant, 2 intake air turbo is controlled by 2 wire actuator, only thing different is 6 leakers don't have an injection pump the injector internally increases fuel pressure. The hpop supplies high pressure oil to all 8 injectors its a simple hydraulic pump, that pressure is monitored by the icp sensor, excess pressure is bleed off by 2 wire pressure regulator ipr, egr was removed so thats not an issue but even that is simple stepper motor opens the valve position sensor measures the position of a pintle same basic valve gm has been using sense the 1980's. 48 Volts is supplied to the injectors via ficm. None of this is cutting edge technology sensors are simple position, thermistors, transducers and inductive ALL can be easily tested with lab scope

My advice would be if your not comfortable diagnosing it don't. First question what scan tool are you using second do you have a lab scope?

It's not that I'm not comfortable doing a proper diagnosis, the problem I have is that the two shops it was at before me have literally replaced everything(refer to OP)numerous times trying fix the issue (slight miss/surge around 2000rpm with or without a load once warmed up), and Im not the type to just throw parts at something, and that's why I'm kinda of at a loss because everything data wise looks perfect once warm, driving down the interstate with the scanner hooked up even while it's missing nothing looks out of the ordinary.


I have a Snapon Solus ultra and yes I have a lab scope

And I'm not getting any codes what so ever