Car running on high revs

Hi all, I have a 1991, cabriolet 1.8 gti and seem to have a problem with the car running at 2000 rpm at idle most of times when warmed up. Sometimes it will run at 1500 rpm, or if I park it up for 5 mins or more and come back to it, it will run at 1000 rpm just about right and will run at this until I put it away for the day. I have tried to check for air leaks in pipes but cant find any. Any help or info is much appreciated and thanks again.

Mine does this could never figure out why I have no air leaks but I find if I squeeze the air pipe on drivers side just behind intake manifold it drops the revs and stay down dunno why


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There has to be something that needs sorting out for the car to do this

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It could be your AAV (auxiliary air valve) is sticking open, it's behind the inlet manifold and is just about possible to remove it from above but it's tight.

Remove the valve and clean it out by spraying in some carb or brake cleaner and look for any black glupy old oil.

You might need to remove some pipes attached to the valve when getting it off the engine if you can't get to the hose clamps.

Valve looks like this.

https://www.ebay.co.uk/itm/AUDI-80-90-VW-GOLF-MK1-2-JETTA-GENUINE-FUEL-INJECTION-AUXILIARY-AIR-VALVE/223614801537?epid=1409354789&hash=item34107b1681:g:KMYAAOSwKO5b2ZlR

Greenmk1 said

Hi all, I have a 1991, cabriolet 1.8 gti and seem to have a problem with the car running at 2000 rpm at idle most of times when warmed up. Sometimes it will run at 1500 rpm, or if I park it up for 5 mins or more and come back to it, it will run at 1000 rpm just about right and will run at this until I put it away for the day. I have tried to check for air leaks in pipes but cant find any. Any help or info is much appreciated and thanks again.

What type of fueling do you have, Carb, or Digifant (EFI).
as that determines what I would suspect the issue is.

Automatic or Manual transmission as well?

Sorry for being blond but how can I tell the difference, I know its a gti

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Spray the hoses and vacuum lines with WD40 while the engine is running.
The revs will dip down when you spray on a hose that's sucking in air, from here you can find your vacuum leak.

Unless the AAV has gone it's going to a vaccum leak, mine did it for ages until I found the right one

Hi all, thanks for the info but I found my culprit it was a broken wire going the AAV plug. It had broken right at the edge of the plug where I had to take the pin out and replace the pin with wire at the end. All running fine now. Thanks again.

excellent, nice easy fix... i still have this issue on mine, the usual fixes havent worked.