Focus Over-Revving?

panthro · 15 Jan 2008 at 13:59

My focus has been over revving and cutting out when idling. I changed the idle control valve today and it has stopped cutting out and it a lot smoother, but it is still over-revving. Does anyone have an idea of what this could be?
I dont want to spend £60 on a diagnostic check and have it come up all clear. Someone suggested to me that it could be an air leak, how would that make the car idle at 4000rpm? Any help would be appreciated, cheers

Phil W · 15 Jan 2008 at 14:09

Badgerpoo · 15 Jan 2008 at 14:51

It could be an air leak after the ICV or after the throttle, that would let more air in and hence rev too high, just as if you had opened the throttle. You can try and spray wd40 on some of the lines and listen for a change in engine note, if some of it gets sucked in, the engine sound will change.

Tom|Nbk · 15 Jan 2008 at 16:10

Reset the ECU.

panthro · 15 Jan 2008 at 16:39

How do I do that Tom?

Phil W · 15 Jan 2008 at 16:42

Disconnect the battery for an hour or so, according to some it only takes 10mins or so, but best leaving it for a little longer just to be sure.

Then drive how you normally would.

Not really sure if its a myth or not though, i have tried it before.