My ultra reliable 2001 2.0 Zetec Focus has had her first fit!

The other day I got some NGK plugs and gaped them at 1mm, car ran better than when I had the Super 4's in so all good there. I then decided to clean the throttle body. I got the throttle body off and gave it a major clean as the back off the flap was coated in black grime. No de-greaser worked so I used fine wet sandpaper and rubbed it off. Put it all back together, started it and all was good. Today I went down the road and noticed as I dipped the clutch the revs went up, then when I came to a standstill the revs would hold at 1,600 for a few seconds then drop to normal being around 900. This got worse as my journey went on, as I pulled into the petrol station the revs were 2,000 and stayed there for 5-6 seconds before dropping to 900. Any ideas on this? Also I dont know if this could be related to the above problem but my speedo sometimes stops working for a minute or so then comes back to life.....although this did not happen today with the high idle.

Any help would be great as she will be using heap loads of fuel and at £1.36 a litre my wallet will soon be empty!

Thanks in advance.

 

did you use a new gasket on the throttle body? iirc its a rubber o ring yes? ive usually noticed when refitting throttles on these that the o ring bareley stands proud anymore so wont reseal properley then you get odd revving as described above
either that or a sticking/faulty idle valve

 

Thanks for the quick reply mate

I didnt use a new gasket on the throttle body......I will get one tomorrow. If that fails then its an idle valve? I just googled it and it looks a sod to get to

 

inside the inlet manifold absolute bastard to do comes out easy enough whole different ball game putting it back

 

i dont remember ever seeing one inside the manifold on any car ever never mind a focus??? they are usually on the front of the manifold, 2 bolt fixing tubular in shape easy to remove and refit, be carefull not to damage the gasket or fit new
i find carburettor cleaner cleans them well
do not disconnect the electrical connector on it with the ignition on as it will log a fault code in the ecu

 

the revving could be because of an air leak from the throttle body gasket so its worth replacing that as a starting point. it could also be linked to the speedo dieing which is a very common fault and does produce both those symptoms. the cause is the vss (vehicle speed sensor) which will be on the gear box somewhere, just check your haynes.

as said the gasket is first to try as thats wht you've disturbed recently but next should definately be the vss.

btw the crap on the throttle is there from new, you didn't need to clean it off.