Hi folks

Bought a 1.4 Focus a few months ago and having trouble with the revs.

If I reduce speed (for example come off the motorway) the revs take forever coming down.

And if the engine is warm and I'm doing a lot of stopping and starting (traffic lights etc) it's really revvy.

If I put the clutch down the revs go right up to 3.

It roars like crazy for about ten seconds then finally settles.

I took it to a mechanic and he thought it may be the Throttle Body (which was seized up), so replaced that and no difference.

Then he thought it may be a crack on the inlet manifold. It wasn't. He also tried a full oil change and squirted WD40 anywhere that might do some good.

Has anybody got any ideas because my mechanic is stumped. I've read on other forums it may be the idle control valve or the ECU.

Any ideas?

Thanks

ICV or air flow sensor would be the next places to consider...

Thanks. I'll take it to a mechanic and mention those!

Apart from the ICV, if there is a air leak in any of the breathers or PCV (positive crankcase ventilation) valve this can cause this,

The throttle is not connected directly to the throttle body, but sends signals to the ECU which controls the revs etc, so the throttle is more like a mouse on a computer or a volume control on a stereo, the part that is connected to the throttle pedal is called a potentiometer (a sort of variable- resistor) it can wear sending spurious signals to the ECU that the ECU may percieve as you wanting more revs

The ECU controls the tickover/ revs, it may be raising the revs to stop the engine stalling,/ responding to another fault - perhaps its due to a faulty sensor (eg the ECU "thinks" the engine is cold/ in its warm up phase)

Finally, it may just be the ECU doing its job.