'03 6.0 Powerstroke. Rough idle AFTER it warms up. Runs fine cold. It seems to studder and miss at mid range acceleration. Egr deleted and new oil cooler installed. New lift pump. Replaced ICP sensor. Have 48.5 volts at the FICM. Replaced the fuel pressure spring to the blue one. All new filters. Does not smoke. Does not throw codes. I need to fix this truck one last time. It has a date with the bottem of a very deep lake! It has been nothing but a pos since it hit the ripe old age of 25k miles! Please help me drown her!
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Just give her to me! I'll be happy to take over the problems for ya'... What are you running for oil? Have you considered running an additive such as Hot Shots Secret? Or one of the others? Have you checked the unison ring for binding? Could be a striction issue I would look tword injection but otters will come along with their input as well, I don't think the lake is nessecary just yet!
Jim&fat Monty

 

Moved to the 6.0L Powerstroke Diesel forum.

 

did you use a motocraft oil filter and stock cap

 

motorcraft filter and original cap.

 

i am changing the oil today and adding HSS to see if it is stiction. Just cant understand why it runs fine until it warms up and then sounds like one or more injectors are not working. Should be the other way around. Runs bad cold then warms up and runs better.

 

Could possibly be your FICM acting up when it gets warm. Have you tested it using the FICM test procedure in the Tech Folder? I would test it cold, and then test again when she's warmed up good.

 

Could be a Ficm like Alan said but those usually get better as the truck warms up check it out Just like he said

I dont think changing the oil will help but couldnt hurt

Stiction goes away as the truck warms up thats a cold running issue

I think that it maybe an injector harness

any smoke

any gauges

 

I agree with you totally.

My truck did the exact same thing, ran excellent cold, once it warmed up...rough running same symptoms as you.

Turns out one of my ficm plugs was slightly loose.

Test your ficm/check connections

 

FICM tested out to 48.5 cold and hot. Almost no variation in the reading. Thinking now to check the IPR.

 

unplugged the icp no change. time to go to the shop. i give up!!!

 

It boils down to how much time you have... A good Ford tech can usually find your problem pretty quickly. They can do a diag for you for about $100 and then you could fix if you want to tackle it. That saves you a lot of time on the front end troubleshooting the issue.

 

sounds to me like when it warms up, the oil thins a bit and escapes through a developing leak in your high pressure oil system. Same problem I had, with same symptoms

 

after it warms up, if you shut it down , are you able to restart with no problem?

 

yes, after its warm it starts fine it just misses bad. It starts and runs great cold. I just don't get it. I have or had 3 6.0 trucks but this is the only early build and the only one with all of these problems. I'm going back to riding horses!