phantomblackgto

You sure the tach issue just isn't the torque converter? My truck, tuned or not, will always hit a spot under moderate acceleration where the tach stays pretty constant, but the speed keeps increasing. Mine is definitely due to the torque converter.

GlockFan24

So I don't know for a fact that your problem directly correlates to mine... but it sounds similiar. As I was having the same issues with my 2010 5.4, just this week. First day it happened and would literally stall out on me while going through the drive through. I called dealers in the area and they had no idea. So I bit the bullet and took it in....


SUPPOSEDLY it was my throttle body that needed to be cleaned due to high carbon build up. Also they updated the PCM with a flash to a newer version. I really don't trust the dealership, and when I looked up this specific problem, all I could find was a thread about how it was a simple 50$ part called the 'EVAP canister purge valve". I mentioned this to the dealer and they said this was not the issue. I get the truck back tomorrow, ill let you know.

Total so far on the service from the Ford Dealership is 550$.... FML

thundergrey

I have the same issue. Had a 5 star tune and when cold the engine would fall flat around the 2000-3000 rpm range. Took the tune out and it is less pronounced but still there. I miss my tune but can't handle it acting up and want it to throw a code without the tune so the dealership will deal with it without hassle.

I did plugs, cleaned sensors, and had an over boost code where the dealer replaced an intake sensor but still have the same issue.

O2 makes sense as the problem is less pronounced after hauling the trailer or a good highway run. Must check.

maplelakeduckslayer

In my case the o2's did make a difference but it fell off again. I did get an oil change that day as well.


I am still trying to figure this out. Some days truck runs fantastic...super smooth idle, holds gears like its supposed to, and can just hear a fine turbo whistle, rpms go up as they should.


Then all of a sudden it will idle rough with the tach bouncing around, it will release all boost as I accelerate and instead of a faint high pitched whistle I get a sound like air getting let out of a tank, it will upshift too early and just lacks power.


One thing looking at the O2's is one side was full of soot one side completely clean. That shouldn't be the case.


Still seems like a timing thing to me...but why sometimes it runs great and other times it will fall off? That's why I am replacing the passenger side vct solenoids, thinking maybe one could be sticking open causing it to over retard, which is why it runs so poorly sometimes.


I don't know, with no codes just trying to look at all possibilities and hopefully one day figure this truck out

laketrout

I have the exact opposite - stock mine falls flat, with the tune it doesn't. However, with the tune I get worse surging, black smoke, and weird turbo noises. Thinking about going to a 2015 with a 5.0 before my powertrain warranty expires.