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Re: [T3] Aux. Air Regulator


On 31 May 2001, at 22:48, Peter Legault wrote:

> While I had the problem I had directly hooked up the relay to an
> ignition connection on the fuse block and disconnected the wire to the
> Aux. Air regulator. I had also unhooked and plugged the air line from
> the breather to the A.A.R.

The AAR is an air valve that lets in more air when the engine is 
cold and then closes off as the AAR warms up; the AT AAR is 
electrically heated and that is what that wire is. If the engine is 
running well and tuned properly, the effect of all this is supposed to 
be to keep the idle speed ~constant during warmup, but it's not a 
perfect system.

>  Upon fixing the relay I have run a new wire to the A.A.R.
> suspecting a short as the wire had heated up with slight melting. 

That sounds like a good idea because otherwise a short would 
blow the fuse which also serves the fuel pump, which would leave 
you stranded.

> When I fixed the relay I hooked the AAR air line back up and all works
> but shortly after a somewhat temperamental startup the engine surges
> and idles kinda rough. After warm up the engine smoothes out a bit but
> still not normal. This evening I have again disconnected the AAR and
> again plugged the air hose and it seems to run better.

There's no harm in that, and in a moderate climate you may not 
even notice much of a difference. The AAR really comes into play 
when it gets COLD, meaning -30 to +30F.

> My question is does this idle problem directly stem from this device
> and how do I test it. For now it is disabled.

Connect the wire and start up the engine cold. Remove the hose 
from the AAR to the air cleaner. Blocking off the AAR air inlet with 
your thumb should cause the idle to slow down, and you should 
feel a vacuum on your thumb.

If you do the same test on a warm engine (with the AAR wire 
connected) you should not notice any change in idle speed since 
the AAR should be ~closed. You MAY feel a bit less vacuum on 
your thumb. 

You can also disconnect the AAR wire and measure the resistance 
thru the AAR to ground. I don't remember the correct number, but I 
suspect that you should get 20-30 Ohms. You could also do this 
test from the fuel pump relay end of the wire to verify that you don't 
have a short any more.

-
Jim Adney
jadney@vwtype3.org
Madison, WI 53711-3054
USA

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