Audi Throttle Body

Ive posted this in my projects section but i think i may have more joy in here. I fitted my Audi TB, ported inlet manifold and supersprint 4 branch at the weekend. But im unsure what to do with this pipe.

The large rubber pipe that comes from the back of the Audi throttle body. The original TB had a blanking screw in a similiar sort of hole but i cant see how the blanking screw will fit in this TB as the hole where the pipe connects to isnt threaded. So we left the pipe in place and started the car without the bolt in the end (as pictured above) Revs were sitting about 700 - 800 at idle but car seemed to go well on the road. Fitting the screw brings the revs up to 1k but car doesnt seem to go aswell once out on the road.

Can anyone who has fitted this throttle body in the past tell me what the rubber pipe should connect to, or what they did with it please.

Thanks in advance

just cap it off as you have above, it'll be for block breather, isv or carbon canister or something.

Thanks for that mate, thats what i thought. The brether appears to run into the back of the throttle body and is diverted back into the larger butterfly area of the TB.

My concern is that the car seems to run better with the screw taken out, however the revs sit about 750 @ idle.  With screw in she idles fine, but doesnt run aswell  :dontknow:

I may wait until my tune up man has been and had a little tinker with the Golf before i decide whether to run with the screw in or out.

without the screw you've got an air leak, which suggests either co is too high or some other problem with the fuel system. 750rpm is a bit low for a k-jet in my experience I tend to set them up to around 900.

Which audi does the throttle body come from? And is it worth just fitting the throttle body, or is it best to fit inlet as well?

This was the Audi 80? one on my mk1 (2.1) 8v DX k-jet engine:


Large pipe blocked off at back ^ ^.

Can see better from my refurb pics:




Large pipe over on the right  & the 2 small ones underneath it ^ ^ ^ were all blocked off on mine.


And the idle screw (replaced with bolt) can be seen over on the right ^ ^.

From the Audi 80 with 3A?

not sure, TSR supplied it when they built my 2.1 years ago. only little down side to it is that it sits the oposite way around in the mk1 so the idle screw faces the bulk head. Bit awkward on a hot engine though not impossible after they put the bolt instead of the screw in it.

looks exactly the same as a MK2 GTI one to me as well. the throttle screw problem is normal, is the same on the oem MK1 throttle bodies as well, hence why the screw pokes out. on the std MK2 8v the screw is burried inside the hole so its best to fit a MK1 or MK2 16v idle screw so you can get a spanner on it

Did the original poster check that the ported inlet manifold is actually ported as well where the TB attaches to it because i recently had to hack at mine after finding out it wasn't (even though i was told it was) though it made 165bhp back then so hopefully with an extra 20% removed & smoothed over it should make a difference.