I recently purchased a 04 F150 with the 5.4 and have been doing alot of reading on them, and it appears there are a good number that complain of a rough idle, my question is how rough is too rough, being this is the first 5.4 I have ever owned I dont know what to compare it too, ...should it run so smooth that you cant even tell if its running if your ears were plugged? Or would there be a slight roughness in most. Why I ask is, mine has that slight roughness, my last vehicle was a 3.0L Ranger and it was always well tuned, but I could "feel" it running at idle. This truck is about the same.

 

Modular engines idle rough. Cleaning the MAF helps smooth out the idle some. There is an MAF cleaning how to thread in the how to section. Also make sure your fuel filter is changed regularly, 15,000 mile intervals.

 

Call your dealer, I think it's $80 to update your programing. The BG or Motorvac service would most likely help as well.

 

Not true across the board. My son in law's 98 4.6 idles so smooth you can't even hear it run, much less feel it.

 

Both my modulars are smooth as glass.. Thats one thing I like about them smoothest engines I've ever owned and i've had a few.

 

Yea, it's the 3 valves that can have rough idle issues, due to the body motor, specially first year 3v's (2004). That drive by wire can be a balancing act with those.

Seems to do better on 4 six. At first they were replacing the throttle motors under warranty, now I THINK they can program it out.

 

There's plenty of '04 to '08 F150's on the road so you could always find another truck or two to see/hear if yours is really 'too rough'.

How many miles on the truck and do you know what maintenance was done and at what intervals? If you don't and mileage is 70k+, you should think about a full tune up, including replacing those lovely plugs that come on those 3V engines. Depending on how mechanically inclined you are, you can just about everything yourself. I would recommend having a shop with a BG or Motorvac machine perform that service; it's well worth it and will save a few hours of taking the intake apart to clean it.

 

Curious, What is the reprogramming called? Don't want to go to the dealer and get the usual dumb looks...

 

Ask if there's an update for your computer pertaining to problem. Look at your TSB's, there's many for the 05, that I know, I just looked at them recently. Other models have them as well.

They will most likely offer it when/if you go in for an upper GI or BG/Motorvac.

 

Upper GI...

 

And I thought no one would catch that lol.