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 Post subject: Revs itself at idle
PostPosted: Mon Feb 17, 2014 9:50 pm 
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Clubman

Joined: Sun Aug 25, 2013 2:54 pm
Posts: 120
Car Model: None
Sorry to bother you all yet again with another issue but my st205 has developed an intermittent issue when warm. What happens is when coming to a stop at idle when warm the car idles fine for about a minute then revs itself to just over a thousand for a few seconds then drops back down to normal. It only ever happens once when I stop but when it's happening it happens every time you rev the engine then let it rest. Could anyone advise me as to where to start looking? Just so you know there is no cel. Thanks guys


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 Post subject: Re: Revs itself at idle
PostPosted: Tue Feb 18, 2014 5:30 pm 
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Clubman

Joined: Sun Aug 25, 2013 2:54 pm
Posts: 120
Car Model: None
Also I would like to add that the cold idle is down to 1100rpm now that this has started happening. It used to be more like 1500 on a cold start. It turns out it's not intermittent I just don't usually sit stationary long enough.


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 Post subject: Re: Revs itself at idle
PostPosted: Tue Feb 18, 2014 5:59 pm 
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Club Staff
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Joined: Wed Jul 13, 2005 12:14 am
Posts: 3265
Location: Camberley, Surrey
Car Model: ST205
I would start looking for vacuum leaks before moving onto other things.

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1996 ST205 UK


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 Post subject: Re: Revs itself at idle
PostPosted: Tue Feb 18, 2014 6:15 pm 
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Clubman

Joined: Sun Aug 25, 2013 2:54 pm
Posts: 120
Car Model: None
Thanks for the advice mate do you just spray loads of carb cleaner arround the manifold or do you have a better way to do this?
I had a look after work today and noticed that a fairly loud click comes from arround the timing belt/alternater area every time this happens. It is not the alternator though as I unplugged it to check.
Also if I let my car idle when warm it happens roughly every minute now not just once.
Thanks for the help so far


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 Post subject: Re: Revs itself at idle
PostPosted: Tue Feb 18, 2014 6:26 pm 
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Group B
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Joined: Sat Sep 02, 2006 3:13 pm
Posts: 3679
Location: Bournemouth
Car Model: None
Could be your aircon cutting in - the pump is at the front of the engine driven by fanbelt with a magnetic clutch that comes in with a click, it also has an idle up solenoid on the bulkhead plumbed into the back of the chargecooler and the inlet manifold. Clamping one of these pipes or disconnecting & blocking would prove.

If it's regular and predictable, but not full time I doubt it's a leak.

The other idle up is the power steering which is a mechanical valve on the bottom of the power steering pump. These usually break or clog with oil. Again, clamping or removing a pipe would confirm, but I doubt this is your problem.

Only other suggestion would be a problem in the idle up valve, but again it doesn't fit symptoms too well,.

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 Post subject: Re: Revs itself at idle
PostPosted: Tue Feb 18, 2014 8:36 pm 
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Clubman

Joined: Sun Aug 25, 2013 2:54 pm
Posts: 120
Car Model: None
That sounds like it could be my problem mate. I think that's what was clicking when I was listening. What pipe should I clamp? The one on that goes to the chargecooler or the inlet manifold? And roughly where about on the bulkhead is it?
If this is the problem which I think there is a very high chance, how would I repair it? Or best just to remove aircon as iv been considering it anyway.
Also just so I can check where is the power steering pump?
In your last suggestion is it the idle air control valve you are referring to?
Thanks a lot for the help


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 Post subject: Re: Revs itself at idle
PostPosted: Tue Feb 18, 2014 11:52 pm 
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Group B
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Joined: Sat Sep 02, 2006 3:13 pm
Posts: 3679
Location: Bournemouth
Car Model: None
Follow the pipe from the back of the chargecooler and you'll find it. Doesn't matter where you clamp the pipe as long as you stop flow (it basically goes round the throttle body via the valve). As for cure, make sure you haven't got a/c or econ pressed as that could be it. Could be faulty button, faulty wiring or faulty aircon control unit. If all else fails, unplug the aircon compressor (front of engine at bottom) and the aircon idle up valve on the bulkhead.

Steering pump is at the back of the engine under the inlet manifold and runs on it's own belt. Access from underneath / drivers wheel arch.

idle up valve = idle control valve.

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 Post subject: Re: Revs itself at idle
PostPosted: Wed Feb 19, 2014 1:51 am 
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Clubman

Joined: Sun Aug 25, 2013 2:54 pm
Posts: 120
Car Model: None
Right here's the new developments just to add some detail. It actually only happens when ac button is pressed in. Silly me didn't even notice it was pressed. There is now a slight hissing coming from the back of the glovebox when ac is active which I presume is an aircon leak. Also there is a whine coming from round about the air con pump which gets higher pitched as the revs rise like a bearing is a bit nackered. Looks like my aircon is finished. Do yous agree? Time to just remove it and save myself a few kilos I think.
Just to top it off my passenger side wheel has so much play now it looks like it could fall off and a headlight bulb is gone lol.
Cars now off the road until the weekend when il have to rectify all of this. No fun for me this weekend.
Any further advice and opinions are greatly appreciated
Thanks


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