Let me start this by saying I DO NOT WANT TO BEAT A DEAD HORSE. I have read and read the threads on here and have not found anyone with my particular problem, here goes. This is my work truck. 2004 Ford F-550, 6.0 Liter, 4x4. Truck has 33,000 miles and they are HARD miles, the truck is a Type 6 Fire Engine for the U.S.F.S. Our typical day is between 50 and 100 miles, however, they are normally throttle to the floor miles, then idle. The problem... when going up a fairly steep hill at 60 mph and the tach reading approximately 2000 to 2100, it starts to bog down Truck is loaded down to almost max weight (keep in mind in this scenario the accelerator is not pressed any harder) the truck begins to slow and the RPM's come down, when it sounds like it should downshift the damn thing starts blowing black smoke and spitting, sputtering, cutting out, the whole nine yards. If the accelerator is pressde to the floor the truck will downshift and take off like a bat out of hell, no more cutting out or black smoke. The truck is going to The dealership on Wednesday morning to get "diagnosed". I would like some 'suggestive advice' for them if I can get it. From the posts I have read it sounds like the EGR valve...but like I said, no exact symptom matches... Thanks in advance guys!!!

 

injector timing

 

I have found my 04 to do the same when I am running it hard up a good grade at 60-70 the only time it has done that is when the water temp gets over 210 wich is not hard to do these 6.0 rads. are trash a wopping 1" thich im not sure if the computer has a back down (limp mode) built in but I do know what you are talking about keep us posted

 

I'm no diesel mech by any stretch, but what if it were a turbo issue, the VGT not working properly maybe. We all know that black smoke is too much fuel and not enough air.

When I bought my 6-oh the turbo was toast (thanks again Jones West Ford in Reno for that thorough pre-sales check up ) and when it was at operating temp would only boost if it down shifted, if it would even do it then.

 

i am thinking like karl

 

I agree Karls seems to be on the right track. I'm guessing a turbo cleaning/replacement is in order.

 

And the winner.....The EGR valve. It was COVERED in the black carbon/soot mix, dealer put it on the laptop and it failed test #2 (EGR valve) replaced the valve and retested...problem solved. thanks for the input guys! We can close this thread please.