Hello everybody!

I am the  owner of a 2017 Focus 1.5 Ecoboost currently having driven it for about 26k km. Ever since 11k km when it has stayed in the garage for about a month due to some personal issues, I've been experiencing some problems.

When accelerating, if I release the throttle and press the clutch, revs go up and come down very slowly. The higher the gear I'm in, the more the engine revs. In 6th gear it even exceeds 500 rpm over what it was when realising the throttle/pressing the clutch. I have to mention this has been happening on and off. Sometimes it goes up by only ~50-100 rpm and goes down as it should and sometimes it goes down instantly. I need to mention that this occurs only when accelerating. If decelerating, everything is fine. I've read about rev hang, which I've noticed when I first drove the car and find helpful at high speeds on the highway and I get it that engine has some inertia, but this is more.
I've mentioned this to my local Ford dealer two months ago when I went for an oil and filter change but the car wasn't manifesting any symptoms then and there were no errors on IDS, so they said I was good to go.

I'd like some ideas regarding the cause of this issue so I can point them to something if the car is ok when going to the dealer. I've thought about the throttle body or a faulty sensor, but the latter would have shown an error on IDS (wouldn't it? :D ) and wouldn't have manifested intermitently. Feel free to toss other ideas around.

Thank you very much.
 

Appreciate this is an old post but I’ve seen the same as what you’ve seen. 

From my own tests I’ve seen the exact same from new on my 2012 model. When depressing the clutch in gear under light acceleration the revs will drop slightly and then hold, and what seems to be the perfect match for the next gear up. 

However, if I’m putting my foot down, but a lot, when I do the same, the revs are either held at the same point or actually slightly higher giving a surge as the next gear is engaged. 

Ive found that both methods give a natural drive according to if I’m cruising or pulling away fast. I’ve never though of it as an issue. I’ve never seen it hold any more than about 400-500rpm over what it was when I’m under heavy acceleration. And always drops to the next gear revs and holds when under light acceleration. 

The thing that bothers me and makes me think this is abnormal is the fact that it happens intermittently and sometimes more sever.

This past weekend I drove about 250km on the highway on Friday and two days later, on my way back, it started revving again and the revs wouldn't drop. The worst I've seen was jumping from 2200 rpm to almost 4000 rpm and holding it there for about 3 seconds, under light acceleration. After a couple of hours stop, after reignition, everything went back to normal. The engine doesn't rev anymore, not even under heavy acceleration, it just drops slowly and holds at a convenient rpm for the next gear.

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this was a standard feature as far back as Mk1 petrol in 1999

its either emissions.... you need to remember all cars run like dogs at idle needing shed loads of fuel to keep them going

gear change help.... when you change down good drivers blip the throttle to save wear on the syncros  / wear on the clutch / reduce snatch from engine braking causing instability when pushing on etc.   it works by better matching engine revs to the high revs the gear below needs - for this the stupid increased revs will provide a better change.  When going up the box its ***** irritating and will do the opposite to the syncros