# cis high idle



## avs0730 (Jan 29, 2006)

i have a 87 audi 5000 quattro non turbo. now the idle is abit high idling 1500-1900 rpm. i lower the idle screw and it went down to 1200 and still nothing. anybody have any ideas.


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## ducksback (Sep 19, 2011)

*throttle body suggestion*

I had that problem with some A1 chassis cars. I usually drive pretty calmly. Now and then after some WOT work, it would get a high idle. The secondary throttle butterfly was getting a little sticky, and at WOT it opens for the first time in a few weeks, then when I would lift off the throttle, the linkage from the primary would close the secondary most of the way but not all of the way. I would have to lift the hood and move the secondary throttle shaft all the way closed. Then when i got home, I'd oil the shaft and with the engine off, work it till it freed up. This would happen once or twice a year. This is something that is quick, easy, and free to check on your Audi. If not this, then make sure that you don't have a vacuum leak or a binding throttle cable.


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## WaterWheels (Aug 14, 2005)

avs0730 said:


> i have a 87 audi 5000 quattro non turbo. now the idle is abit high idling 1500-1900 rpm. i lower the idle screw and it went down to 1200 and still nothing. anybody have any ideas.


I'm not going to claim to know at the moment what is causing the high idle. I can guess as well as the next person but that really does not help. What you have to do is understand how the system works and what could cause the idle to climb like that. Simply put, air is the problem. 1500-1900 is around the boarderline for air with no additional fuel so it could be a few things. In any case the engine is getting more air than it should receive from the throttle or it's idla air bypass. That goes for the ISV if it has one which I believe it should. So testing the ISV, checking for vacuum line leaks or intake boots with tears and throttle valve function are some of the things to check. 

I really don't understand what you mean by ". . . i lower the idle screw and it went down to 1200 and still nothing". Do you mean it does not get any lower? If so then it is because of the false air entering the engine. You have cut off the normal by-pass route but that extra 300-700RPM worth of air is still finding its way into the engine.


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## Glegor (Mar 31, 2008)

start by looking for vacuum leaks.. theres a 90% chance that your issues are from vac leaks..

may need new injector o-rings even. basically every CIS vw/audi needs injector seals..

im going to say that your vacuum leak is going to be a line coming off the main intake manifold. either cracked, or missing..

do you hear any hissing ever? with engine running?


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## anlxn (Oct 18, 2009)

I would say the O ring on the idle speed screw is possibly in need of replacing:thumbup:


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## avs0730 (Jan 29, 2006)

i will check for all of these and post up the my finding


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## avs0730 (Jan 29, 2006)

Glegor said:


> start by looking for vacuum leaks.. theres a 90% chance that your issues are from vac leaks..
> 
> may need new injector o-rings even. basically every CIS vw/audi needs injector seals..
> 
> ...


 i check for vacuum leak by spraying start fluid and the idle didnt go down(an old man show me how). i dont hear any hissing.


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