My company has a 2011 F350 with 6.7. Back in August the truck was running fine with now perceived issues. We had a employee back up to a gooseneck trailer and he missed the hitch to the right. We waived him forward to take a second shot at it and when it put it in drive the truck took off like a rocket. It went about 200' before employee shoved it into neutral. At that point the engine was screaming and he shut the ignition off. That stopped the runaway. When the truck was restarted it was idling fine and did not have any more issues. We didn't drive the truck after that.

We went over this truck with a fine toothed comb including sending it to a dealer for diagnosis. Problem is no one could repeat the problem. Fast forward to this week and the driver was heading back to shop when the plastic turbo pipe broke at the connection to the intake manifold. That caused black smoke and no power. He made it to the shop but it wouldn't pull itself with trailer up the driveway. We unhooked the trailer and he brought the truck up to the shop. He put it into a parking space and just when he started to put it in park the engine took off again. The truck lunged only a few feet and stopped simply because he was already taking it out of gear. The engine ran away and black smoke poured out of the exhaust.

So, today I decided to try to find the issue. I started the truck and it idled fine, it revved up without any problems other than the turbo leak. Put it in gear, pulled it forward, put it in reverse to back up to get a better shot and getting into shop door and it took off in reverse. This time I knew what to do quickly but the inertia caused me to hit a tree with the rear bumper. No major damage but a dent.

So, I checked oil, over full and I believe diesel is the contaminate. Going to have to find out why there is fuel in the oil. This truck got a brand new HPFP, fuel lines, fuel rail, and new injectors not long before all this happened. They have about 5k miles on them.

Somehow, somewhere fuel is feeding the intake side of engine to cause this overrun. When I put it in reverse and it took off like it did it was spinning both sets of duals in the back. It won't spin both sets of duals by pressing accelerator. This thing screams when this happens.

The only thing I can see is the possibility of that diesel oil getting into intake through pcv system. I haven't pulled any parts yet as I thought I would ask here for your thoughts. We need this truck and we won't put it back into service until we have solved this issue. So, I will take any advice you will give. We have a good mechanic at the local Ford dealer and he doesn't have a clue why it would do that.

 

Let me get this straight.

The truck did not have enough power with broken turbo pipe to pull trailer to the shop,but had enough to spin a set of duals with broken pipe?

 

Exactly. It shot like a rocket out of control. It's on video. It was caught by our security cameras. It was in gravel driveway.

 

What modifications does the truck have? You mention black smoke, is it deleted and tuned? You mentioned a bunch of work with injectors and a new HPFP, was it flashed improperly and could a custom tune maybe not be playing well with whatever was done when the injectors were replaced?

 

HPFP and injectors were replace after the first incident. PCM and engine wiring harness was also replace due to a electrical fire. (Again after the first incident). Truck was purchased from State of Texas and had new engine installed in 2015. Truck was purchased in 2016. Engine has 90k miles on it. No other mods. The broken turbo pipe is plastic and broke the end off and that's why it separated.

As I said the first runaway was before these mods. It seemed OK for the last few months until it started this. In between I replaced all the AC components due to compressor failure, that included the full duct work under dash since a blend door was sticking and since this is a first run truck Ford had a service bulletin to change out housing. Other than that everything is as delivered.

Edit to add: Black smoke only after the pipe broke and during the runaway. Once it started after this incident it did not smoke while idling and we have not put it in gear since. We're not taking any chances until we find the issue and resolve it.

 

I would check the throttle position sensor. It may be telling the computer to add more fuel. A runaway motor is a condition where you shut off the key and the motor keeps running because a mechanical pump keeps adding fuel Your condition is where the motor seems to add more fuel like you are getting on the highway. Some how the computer is adding more fuel to the point where the exhaust is blowing smoke past the DEF. When the CAI pipe broke that will cause lack of power because the intake isn't getting enough boost.

 

I agree with the PCV theory, it's definitely leaking fuel in to the crank case (making oil) and might be pulled back in to the intake via recirculation hitting all 8 cylinders. You said all the injectors were replaced? Maybe substandard parts, but one thing seems to be pointing towards the cause, fuel in the oil (you should be able to smell it).

 

when was the oil changed last, making oil? emissions are intact?

Plastic pipe is a known weak stop but never seen it cause this.

 

Engine oil will act as a fuel, so if oil is getting into the intake system, it may cause the runaway. Perhaps the turbo might be faulty allowing that to happen.

 

Oil was fine a couple of weeks ago. Emissions are intact. I am curious to whether the broken pipe allowed the intake to have a vacuum instead of pressure from turbo allowing the oil/fuel being sucked into intake through pcv. Without turbo pressure I am curious if there could have been a vacuum in intake chamber instead of pressure. It would make more sense if it did.

 

That would not explain the first incident as the pipe was not broken at that time.
I still cannot get over how it made enough power on fuel only to spin duals with no turbo boost,
it had to dump a tremendous amount of fuel but you still have to have air to make fire.

 

That pipe is separate from the fuel system. It only has boost not fuel. The 2 are not connected. Reason for the rich fuel mixture is because the turbo is spinning and putting out boost but its not getting to the cylinders so the computer just adds more fuel without boost. I had this happen to my truck and as long as I stayed out of the boost truck ran ok. You were pulling a load so no way to avoid boost.
It just sounds like a TPS to me.
If you can get this to happen you can take it to the dealer and show them. It has to act up for them to know what is wrong. We are just giving you some ideas but without being able to hook up the computer and see what is actually going on we are just giving ideas.
I think I remember somewhere on here a guy was having the same issue where the truck would just take off. Not sure he ever told us the fix.

 

Just an update. We pulled the injectors on the passenger side of engine and sent them off for flow testing. We determined that by doing a pressure test and discovering right side fuel rail was leaking down. We drained the oil. It had just a tad over 5 gallons in the crankcase. This overfill happened in less than 1k miles. One injector wasn't shutting off, it was continuously leaking fuel.

The dipstick level was almost 1' above the full mark. We are sure the runaway was due to contaminated fuel getting past rings and feeding the engine. We are not sure what to do just yet. With that much fuel contamination in the oil it had to wash the bearings clean and we may have more engine damage than we think. I am going to find a borescope and check the piston of the cylinder that the injector was leaking into. With that much fuel it could have burned the top of the piston in that 1k miles of running. Again, new Ford injectors were installed about 2 years ago. If this engine was damaged from a defective injector (and we know one injector is defective) then we aren't going to be happy with Ford anymore. Will post more if we find a damaged piston. We may just scrap the truck if this is the case.

 

I believe that Ford only supplies reconditioned injectors for replacements. I did think that oil was feeding the engine, now we know why. Do a compression test on all cylinders first thing to get an idea of engine wear. A oil pressure check is also in order. As long as the engine wasn't worked hard, there may be no damage, they, can survive a lot of dilution.