[T3] Aux Air Regulator....

[Jim Adney]

On 20 Nov 2012 at 23:31, J. Jonik wrote:

> -  I have Volt Ohmeter, but haven't done that high tech (to me) check
> of Throttle Valve Switch.  But, just to know... when the TVS is set
> properly, when-where should the TVS click happen when moving the
> throttle...by pushing on the accelerator cable link?  Is this Such A
> Close Adjustment that it can't be done by ear? 

If you'll read the instructions, the first thing it says is to do the 
adjustment with the key OFF. With the key OFF, only the 68-9 TVS will 
make a click. This is a mechanical microswitch "click" which you can 
adjust those switches with. On all the other years, there is only 
silence. The click you hear with the key ON in later years has 
nothing to do with the idle contact, so you can't use it to adjust 
the 70-on TVSs.

> - The lurching happens a lot when driving first five minutes...but
> isn't so bad later. When on highway at 55 mph, it happens but not so
> noticeable.  Same elsewhere when just driving ahead. Fourth gear is
> the best.    But When in city streets, going from stop sign to stop
> sign, going through the gears over and over, it's much more
> happening.  But, no sign of backfire, stalling, or the like.   Engine
> sounds great...except for the lurches.  Frustrating.   It seems THIS
> Close to being perfect.

It's vaguely possible that the badly out of adjustment TVS might 
cause this, if you find yourself driving right at the mis-set idle 
threshold. Try to get the TVS set correctly before you do anything 
else.

There is a lurching that happens at very light throttle when trying 
to drive at constant speed in  3rd at maybe ~25 mph or 4th at ~35. I 
don't have a solution to this. It can be reduced by anything that 
reduces drivetrain backlash, like replacing worn CV joints, but I 
haven't been able to eliminate it.

If you get a lurch at highway speeds, try unplugging the TVS. If this 
cures it, a new TVS may be your solution.

For others watching this struggle, please keep in mind that the TVS 
does not need to be periodically readjusted. You can check your 
adjustment without changing it. Except for '68-9, don't follow the 
Bentley; the proceedure is wrong there for '70-on.

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