Fast Idle After 'Workout'

[Guest]

A couple of times recently I have spent a little while driving my S2 as it was designed to be driven for a period of say half an hour. When I come to a stop the engine is then idling at around 1,400 rpm, rather than the more usual 800 rpm. Under normal 'pottering about' conditions, once it is warmed through the engine idle speed is about 800ish, as mentioned above. Any suggestions as to why this might be happening, and whether it is something that I should be overly concerned about?
Cheers,

Graham

 

[944Turbo]

In my experience carb cleaner is better on the idle stabalizer valve,
Tony

 

[944cabby]

ORIGINAL: 944Turbo

In my experience carb cleaner is better on the idle stabalizer valve,
Tony

Yes, i used carb cleaner to do my ISV also a short while back - it did the trick.Bit of a fiddly job but sorted out my irratic idling straight away.

 

[sawood12]

Its been a funny week this week. After feeling pretty smug that I have seem to have escaped alot of he usual 944 issues that plague other peoples cars they all seem to have hit me in one week. At the back end of last week both my fan temp switch and thermostat decided to go AWOL and this week my idling seems to be screwing up. Just reading this thread with great interest and I have a couple of questions: Where abouts do you spray the WD40/carb cleaner? Is it on the actual mechanism that is operated by the throttle cable? The problem I am experiencing is that my idle speed will sometimes and suddenly jump from the usual 850ish rpm upto about 1300rpm while my foot is off the accellarator. It will settle at this higer speed and is steady (i.e. not irratic) and stay there. This will happen when in stationary traffic when the car has been idling fine for a couple of minutes and without even touching the accellarator the idle speed will suddenly jump up. It can happen if the enigne is hot or cold and irrespective of if i've driven the car hard. It used to be that if I blipped the throttle it would settle back down again but this no longer has an effect.

The idle microswitch appears to be operating correctly (I can hear it clicking when I rotate and release the throttle manually) so I don't think it's a case of the throttle return machanism sticking and not activating the idle microswitch - maybe a dodgy microswitch??

Cheers.

 

[944cabby]

As much as i tried i couldn't get the ISV off mine from under the intake manifold to give it a proper clean but i managed to disconnect one of the hoses going in to it and got a good amount of carb cleaner inside.
Mine was idling just like yours - seemed to suddenly start doing it.It's fine now though after using the carb cleaner.

 

[Fen]

The S2 and Turbo are different anyway, but in answer to your question Scott it goes inside the ISV. I'm not sure it's possible to remove the Turbo ISV (though I did manage the S2 one). You can find it as it has a black rubber hose of about 1 1/4" OD running to it from the airbox - it disappears under the inlet manifold. If I remember I'll take a look later to see how accessible the ISV itself is.