DirtMcgirt

This is a common occurance of the ecoboost. There is a thread on it if you search for it, but here it is cause I'm bored.

Quote:
Since the system direct-injects fuel into the chamber, games can be played with the actual flow of the spray. For instance, on start up, when the engine is cold and the catalysts aren't functioning, the engine injects a half-shot of fuel into chamber on the downward stroke of the intake cycle, then, as the piston comes back for ignition, a second half-shot is fired at the piston head. Notice the shape of top of the piston (sans the CNC'd EcoBoost logo): The little trough is designed specifically to ramp that secondary spray at the spark plug — the result is a locally rich mixture good for ignition, but a globally lean mixture, great for making heat fast.

Heres the link
https://www.f150forum.com/f70/black-smoke-87840/

Toolmanbmw

Mine does the same thing when I start it in the morning... and yes you can feel it when sitting in the truck. But I do not notice any change to the fuel econ. Please update us on what the dealer say. I read somewhere that it might be related to the Torque convertor stutter and the dealer can fix it...

6.2Limitedf150

I have the same thing on my 6.2l and the dealer had to order in a part. It is the fuel moister vaporizer. I do believe that will give you a ruff idle. I'm getting mine put in on Monday.

bachey

I also have a rough idle which last for approximately 5 - 10 seconds on start up. But once this time period is over and the engine warms, the revs drop, it seems to be fine and exceptionally smooth. Can't say i notice a drop in mileage as I am breaking the engine in and the mileage isn't great at this time anyway.

Mustang50man33

I have 600 miles on my Eco fx4 screw and have only noticed the idle dancing up and down one time. It occurred after about 45 miles of interstate while stopped at the end of the exit ramp in drive. If it happens again, I will put it in park to see if it still continues. In park the idle is a bit higher. I reluntutly just traded in my 09 xlt screw that I loved and never once had any issues with it. The Eco videos and my sales man along with the big touch screen and backup camera was to much to resist. I really doubt moisture or ethanol is the culprit here. I work at a refinery and am also a dirt bike/atv junkie and ethanol is certainly not what my cr 500 likes. I can not stand the big government ethanol scam as much as anyone. If my truck continues to do this I will be at the dealer looking for answers. This is my first post and feel lucky to find this site dedicated to the only trucks for me. Is there a way to do a word search for forum topics?

Oblivia

Hmm. No such problems with my new ecoboost. Just over 1000 miles on it - normally got about 17 mpg due to constantly changing revs per user manual recommendation (shift limiter works great!). Latest gas mileage for my commute is 20 to 21 mpg, when you drive it easy. Highway miles in the 23 mpg range. Seems to like 60 to 65 mph, sucks much more gas at 75 mph. Idles so quiet I sometime forget it's running - no roughness at all. Gas here is 10% ethanol.

6.2Limitedf150

On my 6.2 the dealer had to replace my fuel vaporizer valve. It didn't have any vacume witch caused my truck to have a ruff idle upon start up. It runs perfect now. So if you have a ruff idle then if you have a ruff idle I would defiantly take it in. You could have the same problem as me.

wdbates

I have noticed a rough Idle at stop signs and warm start ups. Intermitent so far and no check engin light. I suspect that after several drive cycles it will correct its self..
I just turned 1000 miles and not impressed with MPG..close to 18mpg combo 60hwy-40city and I have been very easy on her.