Auxilary Air Valve

Took the auxilary air valve/regulator off today to check and clean up. Says in Haynes that should be clear unobstructed passageway, but when I look through it the plate appears to covering all but 20% of the hole. I assume that this sliding plate should retract fully when cold?

Have flushed it through with carb cleaner and plate seems to have opened a bit more. Is there anything else I can do? If plate not opening fully this would appear explain lumpy idle at 800 rpm for first minute of cold starting.

Cheers

After cleaning and checking I refitted air valve. Car running from cold the same as before (starts first time, but idles lumpily at 750-800rpm for first 30-40 secs, then smooths out at 1000rpm). Squeezed hose from cold start vale to aux air valve/fuel mainfold and this made idle drop. Does this mean aux air valve is ok? Any suggestions what should I look at next?

Cheers

Squeeze pipe when cold - revs should drop.

Squeeze pipe when hot - revs should stay the same.

AAV is OK of both above are true  

Cheers Crazy, haven't tried when warm - will do tommorow. Also forgot to say that hose is a bit tired and worn looking (clutch cable has been rubbing against it). Could the hose be collapsing a bit under vacuum on cold starts and this be causing a low unsteady idle?

Cheers

I have known cases of pipes that look fine on the outside but the inner lining collapses and blocks flow!!!

Could the hose be collapsing a bit under vacuum on cold starts and this be causing a low unsteady idle?

probably not.

Aux air valves usually work or they don't.

I have put one in the freezer overnight and they still don't open up all the way.

Try the squeezing tests when warm and cold as Rich says. If the tests go as planned then these are not the droids you are looking for.

Peter.

 have put one in the freezer overnight and they still don't open up all the way

Yer did myself - opens a little bit more, but as you say not fully. Girlfriend wasn't that pleased to find an aux air valve in amongst ice cream and frozen peas  

Right, went to check hose when warm and while engine idling. Hose is collapsed in middle as under vacuum pressure. When I blip the throttle the hose expands back to original shape, when revs drop hose is sucked in again???

I assume I need a new hose, anyone know if these are available from VW still? (think part number is 067 133 643). Could all this imply that my aux air valve is not closing fully?

Cheers

Could be that both hose and valve are no good.  Get a good hose on there - you could just use vaccuum spec hose of the right size - probably 50p from auto spares shop or 7.92 + vat from VW (joke)!!!!

Would the jury please disregard my last statement.

I'm off to check my pipes.

Peter.

Went to several motor factors today. They didn't have hose with a big enough bore or that was flexible enough for the angle. Tried to order one from local Lindvale VW, they say no longer available? Have my suspicions as they have been wrong in the past about parts for the Mk1 being no longer available. Will try the Wolsey VW who are more thorough. Any other ideas where to get one, maybe local Bosch service garage?

Cheers