My 2005 runs rough in 35-40 degee weather when it isnt plugged in for about a half of mile then runs fine,when left plugged it it runs fine THEY PUT THE LATEST FLASH ON IT AND IT DID NOT HELP.I SWTCED TO 5-40 ROTELLA AND IT STILL DIDNOT HELP.THEY WANT ME TO LEAVE IT OVERNIGHT SO THEY CAN LOOK AT IT COLD.IT RUNS GREAT AFTER A FEW MINUTES THANKS FOR YOUR INPUT

 

Could be a bad injector(s) starting to go bad or slow?

By leaving it with the dealer overnight, the motor and injectors will be cold and then when they hook up their computer and start the motor, they can see what is or is not happening????

When did you last change your fuel filters? Did you change them... and if so, did you use Motorcraft brand filters or OEM/Racor made filters (not just "will-fit" filters from Napa or some auto parts store)?

Do you use an "anti-gel" diesel fuel additive in your fuel at every fill-up to ensure that there is no moisture or water present or gelling of your filters? You need to eliminate the simple and low cost things first!!!

My truck is/was always a little sluggish in the AM when cold... due to "sticktion... which is oil build-up on the oil side of the injectors. SOme of used an oil additive called Rev-X or Hot Shot Secret added to their oil and ran it for the next 5,000 miles with good luck.

If it works... great... the additive cleaned up the oil build-up on the inside of the injector... if not... then your still due for 1 or more injectors.

I just replaced all 8 of my injectors after 184,000 miles in my 2003, but then again, I still had the original C93 stock problematic injectors that my motor was built with and feel very lucky that I went that far. My truck ran so poorly this winter that I could not get over 25 - 30mph for the first 10 miles of driving due to "lazy and slow" injectors. When they warmed up... they were fine... with a little bit of "herky-jerky" on hills.

Some have posted luck with Hot Shot secret and others no luck. Remember, there is no such thing as a "mericle in a can". I have used the Hot Shot Secret and not sure if it works or not, but I sent a sample along with my oil analysis and it came back fine... so there are no ill-affects to using "Hot SHot Secret" and I figured it at least cleaned up my turbo bearings and the internals of my motor. I just think that my injectors were just to far shot after 184,000 to make a difference???

HOT SHOT SECRET:
Hot Shot's Secret | Lubrication Specialties, Inc.

REV-X:
About | REV-X Products, Inc. Truck&B=Diesel

Good luck,