Fiesta MK7 Power Issue

[ConnorJH]

Right were can I start, well I'm having problem with my mk7 zetec s 58 plate and it's really starting to get on my nerves. When I'm driving the car it would all of a sudden lose a lot of power when my foot is on the accelerater, I'd push it to the floor and still nothing so I gotta take it out of gear quickly and rev it then chuck it back in, sometimes that works sometimes it doesn't. When it's happening the rev counter either stays were it is or decreases slightly and the car feels like it wants to slow down, it's really doing my nut in!! I've changed the spark plugs, coil pack, leads, MAF sensor even put some redex in but still the same. There's no engine management light either. I really need some help, don't want to take the car to the garage because I know there just gonna charge me for !Removed! I don't need! I think it's something to do with the fuel system or a sensor somewhere. Tends to happen more when going up a hill but also happens on a flat surface.

Thanks for reading.

Appreciate all the help that's given!

[Tdci-Peter]

5 hours ago, ConnorJH said:

There's no engine management light either.

Have you tried running diagnostics on it anyway? There can be stored DTCs without the MIL on, it often takes two occurrences to set the MIL.

It does sound like fuel starvation (fuel filter, fuel pump, fuel pipes, etc.), or an injector problem.

You seem to have mostly eliminated ignition problems, unless it is the pcm.

Compression problems seem unlikely due to the intermittent nature.

Throttle body (or accelerator pedal sensor) problems would normally raise DTCs, and turn the MIL on.

I am a bit puzzled by the RPM indication, is it true that the gauge is not following engine RPM? That is with the clutch dipped for long enough to definitely let the engine down to idle, the gauge stays up. If that were really happening, it could alter the diagnosis quite a lot.

[DieselPig]

When was it last serviced and by whom?

[Zirk]

Ok, I have many friends with Fiesta's & over the years I have learned alot from their car issues.

Firstly as "Tdci-Peter" stated always start by running a diagnostic as there could be stored/history DTC's.

A friend once had the exact symptoms as your car & after ALOT of frustration and changing of parts we came across a very knowledgeable Ford tech who ultimately fixed the problem by re-flashing the PCM with the latest calibration & clearing the KAM (Keep Alive Memory) & to this day that car has run perfectly.

Unfortunately to do this you will need to either visit a Ford dealer or find someone who has Ford's IDS software & the VCM to connect to the vehicle & since Ford does license it to anyone some independent repair shops may have it but they are going to charge you to do this.

It's usually done in under an hour as the PCM calibration is downloaded on demand upon submission of the vehicle's VIN number & current PCM software version.

There is a way to reset the KAM without IDS, If you want to try it - let me know & I will post the procedure.

It's worth trying as it may give you direction but from experience it is generally only a short term fix and the problem will re-surface indicating that PCM flash is required.