I have a mk.1 focus 1.8 collection model and is one of the loves of my life so far... but has proved to be a great source of frustration recently, and from the mechanics I've been to so far they can't tell me what the problem is.

 

It goes one of three ways - when coming to a stop (I usually go down the gears before leaving my foot down on the clutch in first) the engine over revs to about 3000rpm until I come to a complete standstill. Or when coming to a stop in the same way the car cuts out leaving me to either restart the ignition or bump start. And sometimes it's perfectly fine, such as when the mechanic took it out for a drive last week! But for the most part it's either over-revving or cutting out.

 

Now I've fuel breather pipes adjusted and a new potentiometer (throttle position sensor, please correct me if I'm wrong) fitted but the problem still persists. It did have the alternator replaced but that was a while ago now before this problem started. 

 

Could it be something to do with the alternator? I was thinking maybe fitting a new battery might help, or replacing spark plugs etc.

 

Any suggestion would be very much appreciated!!!

 

Thanks guys.

This issue is usually caused by a gummed up or faulty idle control valve.

Yep IAVC or a split pipe.

+1 for the suggestions from @JONATHAN_11_80 and @F0CUE, the 1.8 and 2.0 Duratec engines are well known for these 2 issues.

If you don't have a Haynes manual, I sure there are some videos on Youtube where people have replaced the rubber pipe and/or cleaned the IACV.

@jenxx49 l know exactly what you're saying 😎 it happened with my partners, I'll say I'm 99% certain not sure what the ivac is but my bet is the emmisions pipe ( l replaced ours with a silicon pipe as in picture ) it'll be soft at the bend at the back of the engine or cracked open..

Problem is l made ours, back of engine is a 15mm fitting pipe but the side fitting is 10mm fitting pipe the silicon pipe is a 13mm wide, enlarged at 1 end and reduced at the other but l would replace your idle control valve too and clean the throttle body and you'll notice a power difference when sorted 👍