Idle increases as it warms up Options

[Catweazle]

Hi all,

I'm new here and have recently purchased a 97 st202 2.0 3gse which I've just changed the head gasket on. I,m not sure it needed one but there were some indications there may have been the start of a leak. I was getting a lot of water (clear)from the exhaust and it was blowing what looked like white smoke,but could be the water condensating? There where also tiny bubles in the radiator, like a sea foam.
On startup after finishing the repair it all seemed fine idling around 750-800 rpm but as it warmed up the revs increased. By the time it was up to tempreture on the gauge it was idling around 1500- 1800 revs. The fan kicks in as it should and other then the high idle the engine sounds o.k. I've had a good look around and there are no obvious signs of vacuum leaks or wires off. I did also clean the throttle body when putting it back together. Any idea on what may could be causing the high revs would be appreciated.

Thanks

This post has been edited by Catweazle: Dec 22, 2014 - 1:25 PM

[Catweazle]

Hi again,
I eventually got to the bottom of this.
The Idle Speed control Valve (ISC) was stuck wide open. This meant that the engine was getting a maximum amount of air entering the engine and therefore the ecu was incresing the amount of fuel causing the idle to be high. Cleaned the valve, which then closed to its proper position and the idle now settles down to around 750rpm once warm. I think this fault may have contrbuted to the amount of water coming out of the exhaust which has now also decreased.

Thanks for your contributions