I've searched for idling problems but it doesn't return any results which I thought was odd so maybe I did something wrong.

Anyway, my 08 Fiesta ST has an idling problem. Coming up to junctions, dip the clutch and the idle drops to about 500, then up to 1500 then settles. It's cut out a couple of times too. The throttle body has been removed and cleaned out, battery disconnected for a couple of hours to reset KAM. Tried to check for any split vacuum pipes but I'm not sure whether I've found all the pipes.

Is this idling problem a common issue and can anyone suggest a fix? Google gives result about people asking a similar thing but no fixes.

Cheers.

EDIT: Forgot to mention that it's been scanned with a Sykes-Pickavant machine and there were no codes stored. It couldn't reset the KAM though, kept saying operation failed.

I had this with a focus, it turned out to be a vacum pipe split. Maybe spraying a bit of Wd40 whilst its running? In theory the revs will pick up if it sucks any in... in theory

Worth a try. I'll give it a go. Cheers.

Just don't go too nuts with hahaha

Idle issues are normally down to a minging throttle body but as you've cleaned it up I'm a bit stuck

It's likely to be a split vacuum pipe or a sensor that's gone/going. I'd run some contact cleaner on the connectors for the throttle body, reclean the throttle body, check the throttle body gasket for splits or breaks. After that I'd be looking towards lambda sensors etc.

Well today the engine light came on for the first time so fingers crossed there's a code stored now. Hopefully that will give me a clue what to look at. Cheers for the suggestions.

It certainly makes it easier for you now, But diagnostics can be very misleading and turn it into a proper head scratcher by the end of it!
Let us know how you get on!

Scanned it with VCDS and it seemed to talk to it but said there were no codes stored. Since VCDS is intended for VAG cars I don't really know whether there are any codes stored or not. I'll have to wait now until I can take it to my mate and use his SP machine again.

With the ignition on, engine not running, the throttle body makes quite a bit of noise, like the stepper motor buzzing. Is this normal on these?

Mine makes a little whine sort of noise when running but nothing I've ever worried about.
Admittedly I've only ever used a snap on ethos scanner and a Davie (DAF trucks own software) So I'm not sure what the Sykes-Pickavant electronic stuff is like but it should still pick up the codes?
MAF sensor maybe? but it's strange that it's stalled on you a few times. Like Dontpannic says it might be worth just cleaning all the bits that are easy to get too

Edit: I've "Borrowed" This from another forum. It's basically what I had on the focus of mine.

"there is a breather pipe behind the throttle body, its kind of buried by the inlet and quite difficult to see they are usually split on these mate, spraying carb cleaner near it doesnt usually make it revup more either for some reason"

Ah that's something else to check for. Thanks.

Yeah the throttle bodies do make a bit of noise, that's normal.

I'd be suspecting a sensor fault for sure what with the engine light coming on. You don't need any specialist equipment to read the codes. A cheap OBD2 reader will read the codes for you no problem. (I got my bluetooth OBD2 reader from eBay for around £5 - connects to my phone and gives me codes and live info).

Quick update for anyone following.

Scanned with the SP machine and fault code was P2138 throttle/pedal position correlation. Could be a number of things that caused this so it's not a great deal of help.

Did a smoke test (as in pumped smoke though the intake) and there was no sign of any air leaks so that's one good thing. Seems as though breathers and vacuum pipes etc are all OK.

Cleaned up lambda sensor connector but it wasn't actually bad.

Checked for moisture at plugs and put some silicone gel in to keep any out. Was dry anyway.

Left wondering what to do now. Could be one of those situations where it ends up a matter of changing parts starting with the cheapest i.e. pedal/throttle body.

Will do a service and also check all connections first. Fingers crossed it's OK after that.

Time to do all this is a struggle at the moment so that's why I seem to bitting and bobbing at it.

Almost certainly throttle body related. I'd take it off, give it another proper clean, inspect the green rubber gasket, sounds like the TPS is playing up (which I think is built in to the throttle body).

Just for anyone following his thread, I never got to the bottom of this problem and have now part-exchanged the car. The dealer was aware of the problem and didn't seem concerned. He suspected it would be a lambda sensor and he may well have been right. That was the issue with my brother's Mondeo a few years ago which had similar idling issue and never showed any fault codes. Had I kept the Fiesta, I'd have looked at lambda sensors and throttle body replacement. I'm convinced it was one or the other.