Btw, some one suggested leaving the filler cap removed (or loose) to allow any excess pressure build up to release but it didn't have any effect and the issue still happens; still as random as ever. We found that pulling over; switching off the engine and restarting fixes the issue most of the time; It seems to me like somthing goes wrong during startup and eventually gets worse and worse and simply rebooting fixes it.
Someone also suggested that leaving the car on a hill (facing down?) increases the odds of it happening - I've yet to try this as our road is flat but the missues did say that she mainly experiences it on the way to work (all down hill) as apposed to returning from work so potentially with the hissing sound it could be related to fuel pressure;
I hate debugging cars; Everything is so expensive - I wish I could just hook a terminal up to the car and log every sensor reading ever and then when the issue starts happenign just take a look at the sensor logs and figure out which fracking sensor it is :-D.
Hi guys. Another fiesta owner with exactly the problem you describe - this is a mk6 1.4 duratec with 14K miles. Engine seems to be holding back when trying to accelerate through 2nd and 3rd, getting stuck and then springing back to life. Seems to happen mainly on cold starts, and restarting the engine cures it for me. While this is happening the idle seems a bit rocky - but goes back to normal after a restart.
Just had a full service and plugs changed at main dealer - problem is still there.
Keep me updated on any progress and I will do the same.