I have a 2001 1.6 Ford Focus which has just been to the garage, where it had cam belt and water pump replacement, brake replacement and a full service. Ever since this, it has been revving higher than usual after ignition or when stopped (at idle). Usually, it’s at less than 1000 rpm at idle - now, it will go up to 2000 for a few seconds, and then fall back down to below 1000. This has been quite a noticeable difference, I’m just wondering what could be causing it? Could the mechanic have messed something up? Or maybe the car is meant to rev like this? Look forward to hearing your thoughts, thank you
Looking for this issue on my favorite Polish Ford forum I've found similar case. Have a look on Google Translated version here:
If the translator failed at some point, feel free to ask me about specific post, I'll translate it myself for you.
To sum up, this behavior might be caused by faulty or dirty Idle speed stepper motor or throttle. If cleaning doesn't help, replacing might be needed. Another thing might be crankcase ventillation hose. Some people report that replacing it (as it was clogged) also fixed the issue. Another thing might be the faulty clutch sensor.