Hi all
Have a 1.25 Zetec S Ford Fiesta Ghia on an R plate. A few weeks ago, it started having idle problems. Basically, when it is thoroughly warmed through - not just warmed up according to the temp gauge - it starts to have issues with being able to maintain idle speed as you approach junctions or roundabouts or get stuck in traffic. Anywhere that you dip the clutch basically. The rev counter drops below 500, and it comes within a gnat's c*ck of stopping ( it actually did stop once just as I rolled out onto a roundabout ... ). Mostly, it recovers though, and settles back to a pretty even 900 RPM. When it has reached the point where it is doing it, if you leave it idling, it will sometimes start to get very 'lumpy', although the rev counter is dead steady, but slight throttle pressure up to say 1100 RPM, and it's dead smooth again. So far, the garage have tried the air control valve ( ? ) an electrically operated valve that is something to do with idling, apparently, but this did not cure it, so they put the old one back, then last week, they say that they managed to persuade an error code out of the EMU, that indicated a problem with the MAF meter, so they replaced that. Today, I drove into town, and it started doing it again, so I guess it's not that. On the way home, it started doing the opposite, and 'hanging up' at like 1200 RPM when it went to idle. It is going back in again tomorrow, but they seem to be at a bit of a loss. A couple of people have told me that these suffer from bad spots on the throttle position sense pot, which seems reasonable, but I have poked and tapped it, and it doesn't seem sensitive. I have also heard that the setting for the rest position at idle of this pot is critical, but prior to the trouble starting, it had not been touched from factory original setting.
I'd really like to get this sorted, as it's a bit dangerous if it cuts out on a junction. Any thoughts or advice would be much appreciated, or indeed, if anyone has had this problem and knows what it is for sure, please share with me !!
Thanks
Geoff