its a supercharged fiesta st it was idleing at 1.1k an when you change gears or stop it would hold up the revs for a second then drop.
now its holding at 1.8k-2k all the time making it undriveable.
i cleaned out the throttle body an no luck so i used a small amount of sealer around gasket incase it was sucking in air an still the same
ive disconnected the battery to try an reset it an that didnt work either!
its my only car now an need it to be right!
any help will be appreciated thanks

 

Have you tried cleaning the idle control valve?

Any other air leaks, are all the vacuum hoses to the inlet and air hoses on properly?

 

where is the idle control valve? i just cant see one on it..
ive sprayed throttle cleaner on the vacuum pipes to see if tje engine picks up but nothing

 

Afaik the st has no idle control valve, idle gets controled with the throttlebody.


edit: i tink there must be a leak somewhere

 

I think for the ST the entire throttle system is an electronic fly by wire jobby and doesn't have a mechanical idle valve. Sounds like it has gone a bit haywire at some point. Try eliminating things one by one starting with the TPS and going from there.

 

Air intake temp sensor? would run it really rich/high idle if it wasn't getting a reading...

 

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

 

It's either an air leak or ISCV causing the fast idle!

If you can unplug the valve, if the revs drop (or stalls) then the valve is opening to far giving this speed!

I am sure the ST would have a ISCV?

Martin

 

as mentioned previously in the thread they dont have iscv's they have a fly by wire throttle that carrys out the functions of the iscv and throttle position

 

Oh cool, you learn something new everyday, so does that mean they don't have a TPS either?

Martin

 

thanks for all the replies i got it sorted now cheers all.

 

out of interest what was the problem?
i cleaned my throttle body to help with idling and it now idles smoothly but when i stop it the revs drop to 1200 then step down to 1000 then settle on 900 any ideas?

 

to be honest mate mines exactly the same but im happy with it compared to it sitting at nearly 2k so wont fiddle anymore.
goodluck tho.

 

seems to be sorting itself done probably 60 miles since i cleaned it and it now idles steadily at either 800 900 or 1000 mostly 800ish tho with rests at 1100 and 1000 being a lot less. iv had it in test mode on rpm to watch it but seems to be getting better so hopefully its just adapting. cheers