High Idle Issue

[Rennwagen1]

So my 84 GTI (1.8L 8V)has always had a high idle. It usually settles aroung 1200-1300 when it warms up. I have the idle set screw on the TB turned all the way out, so when it returns, it pretty much rests on the TB itself. I am guessing that I have a vaccuum leak somwhere, but I have looked all over the place, and also replaced the aux air valve, intake tract seems solid, I am at a loss on this one. Any suggestions? It has always idles this way for the most part, but I never really minded, as as lower RPMs the poly mounts shake the shit out of the car, but I would just like to figure it out for myself.

[Roadhog]

clean isv.

[Rennwagen1]

does is have one? I thought they started with the 16vs? Maybe I am calling it something else.

[Roadhog]

i think they have one.

[kompressorgolf]

its not really an ISV its under the TB and much smaller than a generic one, theres not much you can do with those, you can try to clean it. also check your vacuum reservoir, i think its down under where the battery tray is, looks like three tennis balls stuck together. take it out and visually inspect it. it may be cracked from a bouncing rock or something, also the green vacuum line that runs to it, sometimes leakes where it enters the can. injector o-rings, intake gasket, REMOVE/inspect all intake boots esp the one on top the fuel dizzy. replace all small rubber vacuum portions. i love rabbits

also check all vacuum inside the car as well, if its an A/C car the vacuum distributor inside gets weak and bleeds. usually if you cant get the hot/cold air to go where you want it, thats the bastard. those later cars have vacuum controlled flaps in the airbox one may be shot or the vacuum commin from the rain-tray on the pass side may also have a crack from the years etc.

[Rennwagen1]

Thanks, B!

I have replaced th injector o-rings, and I think I eliminated the vaccuum res. a few years ago, to clean it all up a bit. Maybe that was a bad thing? It is not an a/c car, but I will chase tubing through the firewall. Thanks, those are all great suggestions.

Speaking of leaks in the cabin, My shifter OE shifter boot is torn, could that be the culprit?!

[Mikewire]

its not really an ISV...

Look at the brain on B! Seriously nice knowledge there...

[kompressorgolf]

I have a rabbit portion next to the abdula oblongatta.

[MT-Getto]

How about the o-ring on the TB screw? Make sure the plate in the fuel distributor moves freely and is aligned properly?

[golfcuntry]

you should get some carb and choke cleaner and spray it in the engine bay where suspected leaks are, the vacuum leak will suck in the combustable stuff and idle will rise, it will at least help you know if it is actually a vacuum leak. is your timing spot on? fuel dizzy ever been tampered with??