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Hey guys im sorry to trouble you in a New topic,but i thought that this problem may be different.

So here we go.Idle problems,started after an engine cleaning,and after the car had been laying still for quite some time(according to previous owner).
I havent got my hands on the car but i will be getting it on Saturday.We drove in it and accelerates perfectly,no misfires,no bumps from the engine,A/C works perfectly and breezes the hot Greek air at this time of the year.

On cold start the engine idles smoothly.The owner states that the problem seems to appear when the engine has been working,where the idle flactuates from 400 to 750rpm to 800rpm and if the A/C is on it becomes more evident.
Things that have been already done for this issue to the car are:

1)temperature sensor has been changed recently
2)ISV cleaned
3)spark plugs also cleaned
3)MAF checked
4)injectors cleaned(but mechanic told him that due to the car not being used they may have been fairly dirty and probably the issue will be resolved after the car gets moving again)
5)Air filter checked

Could it be the lamda sensor?could there be an exhaust leak somewhere?Hall sensor?

What is the idle micro switch?what does it do?
Also what is the dump valve that has been mentioned before?

thanks
Vasilis

Vasilis

here is an excelent site for you to spend hours going through with some usefull info some of which is relevant to our 20v engines.

http://www.sjmautotechnik.com

For the ISV info see here:
http://www.sjmautotechnik.com/trouble_s ... .html#idle

To do an output test which includes testing the ISV:
http://www.sjmautotechnik.com/trouble_s ... html#outs4

You will find the black, brown and blue connector that is mentioned within the fuse box on the left hand side. Although it sounds a bit complicated and daunting, it is in fact very easy to do. If I worked out how to do it a man who has been through medical school will find it really easy. You can use a couple of paper clips or some fuse wire to activate the output test.

For fun and without a handy vagcom you could also try reading the blink/fault codes, see here:
http://www.sjmautotechnik.com/trouble_s ... v.html#led

and here:
http://www.s2central.net/blinkcodes.html

HTH

Angus

Thanks Angus!
Hey are you located in London?which area?I will be in London for 10 days from the 12th till 23d for some course!

Vasilis you have a PM.

Also have a look here for more idle info and another easy test on Throttle Switch Potentiometer/TSP/TPS?? :

http://www.sjmautotechnik.com/trouble_s ... throt.html

there is a vaugely relevant thread starting on the S2 forum about the Throttle Switch Potentiometer may be worth keeping an eye on. maybe not.

http://www.s2forum.com/forum/showthread.php?t=10716

angus

Here is another useful site:

http://www.s2-audi.co.uk/

and specifically for your current issues:

http://www.s2-audi.co.uk/tech_articles/motronic.htm