[T3] '72 FI won't idle down

[Jim Adney]

On 10 Jun 2026 at 17:46, Max Welton wrote:

> Reason I asked is that I have an AAR and it was leaking air when warm.
> Basically it wasn't closing completely. I was able to adjust it to
> minimize the leakage.

The AARs never close perfectly. Even when "closed" they still let thru an 
insignificant amount of air. They should be "closed" well before the engine is 
fully warmed up. I believe VW/Bosch says at 122 F.

The test is to cover the AAR inlet when the engine is fully warmed up and 
running. The idle speed should not change.

If you do the same test on a cold engine, you should hear a signifcant drop 
in RPM.

Putting your thumb over the inlet and feeling for vacuum is the wrong test. It 
will always mislead you.

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