Hi all,

I have a Focus mk2.5 2009 with 33k on the clock. I've had it 12 months and ever since i've had it there's always been an issue whereby 50% of the time within the first 15 min of driving i if i pull to a junction the revs drop to say 500rpm and bounce back to 1500 then down to about 1000. It stalls or threatens to stall when the revs drop of course but the frightening thing is that it has stalled on roundabouts so my partner is now scared to drive it. It is also sometimes a little hesitant to accelerate like a second before it accelerates.

I know it's had a new battery before i bought it so could it be that they didnt recalibrate the throttle idle? Would it be worth taking the battery off for 20 min to reset the PCM and then go through calibration of idle relearning?

Also today the better half was driving it and apparently in second gear going round a roundabout the car dash lit up as if stalled with no power then applying the accelerator the power came back as if it had started itself? It then continued for about 50 yards and actually stalled. Starting up again and drove fine.

Plugged diagnostic in and nothing.

It sounds like two different things but perhaps connected? Could it be an earth somewhere? I had it serviced in summer and they couldn't find anything wrong. Plugs new, mileage low and service history excellent, however it definitely appears to be better in summer, now winter is here it's certainly worse.

Any ideas?

Many thanks

Brendan

This happens to my focus with the 1.8 duratec petrol engine. 

Ive located the fault to the o2 sensor. 

But to avoid the stalling. Turn it on leave it for 10-15 mins  then turn it off the reastart it. Works a treat