1st post so be gentle !

I have a kit car fitted with a Sierra 2.0 8V DOHC with the stock engine management and injection.

Recently when starting from cold the idle has been going to around 1800rpm before dropping back down - if you then blip the throttle, the idle sticks again before dropping.

This carries on until the engine is warm and the ignition has been swiched off once - it then idles perfectly as it always did.

If you disconnect the ISCV wire when its doing the high rev thing it idles at normal idle 900rpm ish even when cold.

I think the ISCV is working ok but something is telling it to hold the revs high - any ideas what is what ? I have soaked the ISCV in petrol and it appears to move fine but im not sure 100%

I think it may have started doing it after fitting a new alterantor belt but cant be sure exactly when it started.

Car seems to run fine apart from this.


Thanks

 

Have you checked the crank case breather and pipe?