Idle speed too high

Hi guys

I recently bought a 1983 1.8 gti. The engine starts and runs fine apart from the idle speed which is too high around 1200 to 1500 revs, if I blip the throttle it sometimes comes down a little but then goes back up. I've tried to adjust the idle speed on the screw but it makes no difference.
Any help would be much appreciated.

Thanks Andy

  

Which screw have you twiddled to adjust the idle speed?

Early-1800 said

Which screw have you twiddled to adjust the idle speed?

Hi, I've screwed the 7mm hex in and out on the back of the TB which makes no difference at all.

does it have an intact and complete rubber ring/washer on the screw?

Here is a good source for them

https://www.maxrpm.de/#bms_q=Idle%20screw


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Early-1800 said

does it have an intact and complete rubber ring/washer on the screw?

Yes the rubber O'ring is in place and in good condition. Screwing it in all the way makes no difference to the tick over.
I did take the screw all the way out and the tip of it was black and sticky with soot, is that normal?

Any more help and advice would be much appreciated.
thanks

shouldn't be soot as its up stream from combustion, might be oil from the crank breather that is fed into the air intake

strange the screw isn't making any difference at all, check the hole isn't bunged up with crraap and thats these no other air leaks. loose/split hoses anywhere

Early-1800 said

shouldn't be soot as its up stream from combustion, might be oil from the crank breather that is fed into the air intake

strange the screw isn't making any difference at all, check the hole isn't bunged up with crraap and thats these no other air leaks. loose/split hoses anywhere

X2  Vacuum leaks are a real issue with these guys and still original vacuum hoses.