(Very) High Idle Problem....

[Ednamillion]

Problem with my '96 UrS6.

On start up (since yesterday, lunch time only) car is idling at about 2,200rpm. Whilst driving I can feel the car continually pulling even with my foot off of the accelerator (trans is automatic). When I stick it into 'Park' engine can be idling up to 3,000+!

What might be up? In my naivety I assumed that the throttle cable cam pulley (you know what I mean?) was spring loaded and once you lifted off of the pedal the cable et al returned to a 'normal' closed position, no? In fact, when parked and if I pull the accelerator pedal up with my foot - idle comes down....Cable problem? Sticking?

Anybody with any suspicions?

Thanks,

Edna'...

[S2 PTH]

Idle control valve? By that I mean when its flicking over from the throttle pedal to the idle control valve theres a problem. In my old car i could make it stall if i jabbed the throttle and then backed off prematurely when the car was cold! And it was only an R-reg car!

[Ednamillion]

Thanks for your reply, S2 PTH,

Shouldn't the fact that I can reduce the idle down to (more) normal levels by hooking my foot under the pedal and pulling up indicate that the cable is sticking? Or that the spring return on the pulley cam is shot?

I guess I'm hoping it's something so simple....

Edna'...

[Keeper of The Kitten]

Sticking throttle, a very real possibility - worth giving it a clean up around the quadrant and butterfly shaft, it's happened to me before!

__MDC__

[twoqu]

Hi!

Disconnect throttle cable from throttle body. Start car if idle now correct then it points to the cable.
Or get an assistant to observe whether the linkage is against the stop. In fact if you shut the car off when the idle is high without touching the pedal, you should be able to see that yourself. If the linkage is against the stop and the idle is still high then it looks as though its your ISV. In that case pull the connector off and see what happens!

[Ednamillion]

Keeper Of The Kitten, twoqu, thanks for your replies.

As far as cleaning down the throttle cable/linkages, are there any particular methods, cleaning agents, tricks I should know about?

With regard to the IVS (which, looking around a couple of other threads I take is the Idle Stability/Stabilisation Valve?) - looking through my Bentley eBahn disc I see no refernece to an IVS. I do see an Idle Air Control Valve (located right beside the throttle body) - could this be the same thing? Could this be the AAN version of the IVS?

I'll look to disconnect it and see if it alters anything. I'm pretty sure the throttle cable is not returning to it's stop - it needs to be pulled to meet it.

Thanks for your help again, guys.

Edna'...

[Ednamillion]

Just a quick update on this. Yesterday the idling problem developed into a cycling from about 1200rpm up to about 1700 rpm and back again. Occassionally, whilst driving, depressing the throttle resulted in nothing more than an increase in heartbeat as I coasted to the hard shoulder.

So, picking up on a suggestion earlier in the thread once home I left it idling at about 1900 rpm and disconnected - what I believe to be - the Idle Air Control (IAC) valve. Lo and behold, revs down to (a still high) 1100! Re connected and up the revs went again.

So my assumption is the IAC valve is shot and in need of replacement. Here's hoping...

Edna'...

[mcandmar]

I would pull the IAC valve off and clean it out with carb cleaner, there may be other issues causing it to do that, if you have an air leak for example the ecu will be trying to correct the idle speed which can cause it to hunt around.

Nice to see another Irish forum member by the way

[twoqu]

Hopefully it was this you were disconnecting!

[Ednamillion]

back at ye' , mcandmar, although, to be honest, I feel a bit of an intruder in here what with my 'soft' S6...

I'll take it that carb cleaner is reasonably easy to come by? And just clean the connectors? Could there be issues with the valve itself - sticking, dirt?

twoqu - yes, that's the one! Is this also known as an ISV?

Thanks for your help, guys.

Edna'...

[mcandmar]

Not at all i'm the cheeky fecker with a CQ20v and S4, everything but an S2

Clean the inside of the ISV out as they can get sticky with the carbon build up inside it. You should be able to move the valve freely with your finger if its ok.

[Ednamillion]

Ok, I'm not trying desperately to keep this thread going beyond it's usefulness - and also, I hope, not making a mountain out of a mole hill....but...

I'm perplexed. Cleaned out the IAC valve (nice and shiney now - can be moved with little finger) but this didn't change much. Disconnecting the connector on the valve changed the idle down slightly. Disconnecting the throttle cable brought idle down to normal!

What does this mean!

Scenarios:

1. Area around the pulley cam is sticking (looks fine though).

2. Throttle cable, along it's length somewhere, is caught/sticking? Is this easily removed entirely? Can it's full length be flushed?

3. Any others?



Edna'...

[BRY]

Has your accelerator pedal starting coming loose and is not returning to the correct position?

[Ednamillion]

Hi BRY,

Can't say it is/was loose. Didn't really feel any different just before the idling problem originally hit.

The cable is becoming the main culprit to me though. Anyone replaced one before? Big/small job? Part number even...?

Edna'...

[maRS2]

changing cable is a 10 mn job