I too am suffering with the dreaded rough idle....no CEL or DTC's.

I'm about to dump this truck for a '12 EB FX4

 

I have the exact same problem. I'm about to change my plugs again.

 

i still have the same problem after changing plugs,air filter,adding gas treatment,cleaned throttle body,cleaned mass airflow sensor.I have read that it could be due to a possible vacuum leak but i havent gotten around to that just yet.Mine only does it after its warmed up a bit.

 

Try to seafoam it, if the vapor comes out anywhere other than exhaust than that is where the vacuum leak is!

 

We have the same symptoms. It only idles rough when warm/ hot engine. I did everything so far but rechange the spark plugs and change the cops

 

My truck is a 2004 If i understand the mechanic correctly the left bank is the last place to get oil when it circulates through the engine and with so much play in the crank it doesn't have enough oil pressure to keep the left cam in time that is why the whole left bank is misfiring. I was told that i could put new thrust bearings in the engine but several had already been done this way and it doesn't last long the motor starts running bad again after a short time and that the best thing to do is drop the new latest motor in.

 

also i contacted ford mo co about this and they basically said "i don't care" if so many of these engines are doing the same thing it looks like ford might wan't to do something about it or they're going to loose customers i know if all i'm going to get out of their engines is 120K i won't be buying any more new ford that's for sure.

 

Easy enough to test the oil pressure theory. Get a real oil pressure gauge. Check cold and hot pressure. Also check compression on all pistons.

What weight oil have you guys run since you have had it?



From another forum. Might be worth a look.



Change your oil.
Had the same thing happening on my recently acquired 04 F150 5.4L with 212K on it. Had the sounding like a diesel thing going on. Changed the VCT solenoids and the cam phasers. Sounded better but still would have the occasional rough idling when warm and random codes being thrown.

Changed the oil from the 5w-20 Pennzoil Platinum to Shell Rotella 5w-40. I have put on over 1000 miles on it since and no codes and no rough idling. I think in my situation the 5w-20 was just too thin when warm because of wear on the engine. Engine runs smooth now with just the injector tick.

Before spending the 12K for a new engine change your oil to a 5w-30 or 5w-40. Cost you less than $50!

 

I've really been leaning towards trying a 5w40 but I've read so many posts from others saying to stick with the 5w20....I've actually ran a 5w30 many times before but it still idled rough. This was with regular conventional oil though.....I think I'm gonna first try a 5w30 synthetic blend then possibly move to a full synthetic 5w40 if the problem still continues.

 

Be careful changing oil viscosity on your engine. I'm not that familiar with the topic enough to tell you why (lol) but I remember moderator Bucko talking about it recently. (searched but couldn't find the thread).