[T3] my long term issue have to unplug TS1 for a smooth idle.

[Jim Adney]

On 30 Sep 2019 at 13:16, William Jahn wrote:

> The idle didn't hang like it did before. Still when I first started it the
> RPM was a bit higher than 850 it increased by 50 RPM and it then climbed to
> 1200 seems there is a lag before the AAR brings the idle up yet it does get
> to 1200 faster.

The AAR should be partly open when you first start, and then close off 
completely once the engine is warmed up. But what if yours is sticky? If it 
only moves under engine vibration, it might remain fully closed as the warm 
engine cools down. That would give you a low idle when you first start up, 
but would then increase the idle as the vibration lets it open. As the engine, 
and the AAR warm up, the AAR would close down again.

You can test this by putting your thumb over the hose leading to the AAR. If 
it does nothing when the idle is ~900 but slows things down when the idle 
has risen to ~1200, you know that it's at least partly due to the AAR 
changing.  

>  I don't have anything to compare the way mine starts with. Jim when you
> start your 73 what do you notice ?

My idle starts out a bit high, then slows down as the AAR warms up and 
closes. In other words, the AAR seems to be working correctly. I don't think 
my idle every gets even close to 1200. The AAR is NOT actually supposed 
to increase the idle speed at all. It's supposed to increase the engine power 
when it's cold. Ideally, this would be just enough to overcome the increased 
friction of the cold oil.  

Note that the idle speed should be set with the engine warm and the AAR 
fully closed.

If the balance between the AAR opening and the viscosity of the oil is not 
perfect, and it never is, the idle speed of a cold engine in cold weather will 
be diffeent from what it's set at when hot.

When your idle speed gets up toward 1200, that will start to bring the mech 
advance into play, which will increase the RPMs even more. It's possible that 
you have the AAR closing at too high a temp. The adjustment does not 
inclrease or decrease the total opening amount, it only changes the 
temperature range over which the opening occurs. There will always be 
some temp when the AAR is fully open and another when it is fully closed.

I think you took your AT AAR apart and cleaned and adjusted it. I've never 
taken one of those apart, but I've done lots of the MT ones. This has me 
wondering if you have yours closing at too high a temp.


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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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