Took my truck into dealer yesterday for low power when pulling my 7000# enclosed car hauler. I have a 2004 F250 PSD Automatic with 373 gears. It has started to have to downshift on even small hills to maintain speed. It use to be able to pull the same hills at 70 with the cruise on with no downshift no problem. They ran a DTC, KOEO, KOER, KOEO injector self test and they said they all passed. They also ran a Turbo Boost test and it passed at 27 psi under load.
Can anyone expalin these tests to me and let me know if there were any other tests they should have run?
They tell me that there is nothing wrong with my truck, but I know it is not as strong as it use to be.
The truck is all stock except the intake elbow, I put it on to have a place to put my turbo boost gauge with out drilling.
Any help would be appreciated.

 

Has your cooling fan been coming on alot? If youre not losing coolant, you are having the same problem as me, I am suspecting the thermostat, perhaps not opening completely, computer sees coolant overheat (not neccesarily showing on your gauge), defuels engine. I already baught one (33 bucks) Ill let you know after i change it. I believe the injector self test is to make sure they are all contributing equally. the turbo boost test simply verified that the boost pressure is good. The problem as I see it is simply an overheat that the computer is protecting the engine from by restricting heat (fuel) from your engine.

 

The temperature seems fine. It is not running any different. There has been no puking of coolant. I thought maybe vanes sticking, but the dealer said no it checked good.

 

If it happens again take asap to dealer, get documented.

 

It is that way all the time. The power is down and so is the mileage.

 

Have you changed your fuel and air filters recently? How many miles and what kind of fuel are you running?

 

Yes filters were changed at 45000 and I now have 47800.

 

Running the same fuel as always from the same station. It does not seem to mater where I buy it. Local or on the road. I always try to buy from a truck stop or high volume dealer.

 

Maybe a partially clogged EGR valve. Did the dealer do just a boost test or did they actually command the vanes and verify their proper operation? I lost about 2 MPG when my turbo vanes stuck at about 46,000 miles. I thought you only had the problem while towing up hills sorry for the paragraph.

 

I do not know what test they did. They said they did the Turbo Vane test and it passed, what ever that means.

 

The vanes are what would be sticking if the turbo was having problems. So they checked good. I changed my thermostat and tested the old one, it tested ok, and I havent noticed any difference in operation, Changed the coolant, added an EGR block off plate and still havent noticed any diff. Im beginning to think the last reflash changed the cooling strategy to kill power at the first sign of mild overtemp. When was the last time your truck went to the dealer (what flash?), does your cooling fan come on alot when towing?

 

i took my 04 in for the wiring harness recall and a week later i was having some coolant leaking and the fan would come on , but the tempgauge never moved.. anyway they said that the egr cooler was leaking and replaced it.. that was in august at 36k.. i do not drive the truck very often now has 39k and when i pulled my 5th wheel which weighs 8k the fan came on almost every time i would pull any hills.. the temp outside was around 75 .. it never did this before.. before i took my truck in back in august it would idle kind of rough and surge, but after i got it back it idles very smoothly.. now i have noticed that it does downshift a lot more than it used to.. and sometimes when i push the throttle down it will act like it does not want to go unless i floor it then it goes fine.. another problem that i still have is that sometimes when i push the throttle down enough to accelerate but not downshift it will make this air blowing sound and the engine will act like it is missing or something but if i push it on down to downshift it runs fine.. i complained about it at the 36k service but of course they could not find anything wrong with it.. it gets worse as the load increases

 

04f250psd, Took mine to dealer (good diesel tech) today, The tech called me and suggested we take my trailer for a drive with the scan tool hooked up, he found the oil temp was higher than it should be and diagnosed as a restricted oil cooler. He said it was not an uncommon problem. My truck is the same as yours and is acting the same as yours. Ask the dealer to check the oil temp to water temp differential in order to check for a restricted oil cooler. Good luck.

 

My 04 F350 6.0 has been acting the exact same way as well. It only loses power when climbing hills for over 3 minutes with the fiver hooked up (15K lbs). Max boost goes to 15 psi and the foot is in it the entire grade. The dealer has replaced the EGR cooler, oil cooler, EGR valve, Turbo and VGT Control Valve. Still behaves the same. I took a video of it this weekend to show them how we have full boost and good speed for the first 3 minutes of the climb then the boost falls off and we slow down to as slow as 25 mph. It only does this on the high power, high load conditions. All other times, it runs perfectly. It was in the Dealer today, they saw the video and consulted with Ford, as all systems checked out fine. They were told that the engine oil temps could be reaching up to 220 F and causing the engine to go into an automatic derating mode to cool down the oil and prevent engine damage. They also want to give me a scan tool to hook up to it and record all parameters the next time that this happens. I have been reading through this forum that this has been fairly common with the 6.0. Argg! Now I am looking for an aftermarket oil cooler that we might be able to install to help it out. We love the truck, other than this issue, and don't want to be forced to buy a new F450. Any suggestions to solve this high heat condition would be appreciated.

 

Where is the oil cooler located? In the front grill?