[T3] My final question on IAD's

William Jahn willjahn975 at gmail.com
Thu Jul 20 10:09:42 PDT 2023

 I looked around for info. All I could find basically is the MPS port was
moved to the top left side and the temp sensor was moved to the right side.
I read the idea of moving the MPS port to the top was to keep oil or oil
vapor from getting into the MPS . This may be true since I have had a few
of my old oles that no longer work and never found oil in them.

 Tram sent me one with no play at all in the shaft and it has the PCV pipe
but the MPS port is on the bottom left and the trans modulator port on the
bottom right both are right next to each other. and it is for an auto
trans, (proper linkage for the kick down) .

  I did notice on the 72 and 73   IAD the two trans ports have a built in
restriction same as the MPS port but on the one Tram sent the MPS has the
same orifice/ restriction as the late model but the trans port does not so
maybe this is how they made it work with one port. I did read somewhere
that many create a loop in the MPS hose to bring the bottom port higher up
to help prevent oil vapor from entering. .

On Tue, Jul 18, 2023 at 9:49 AM Jim Adney <jadney at vwtype3.org> wrote:

> On 17 Jul 2023 at 14:32, William Jahn wrote:
> > I was curious why there are two ports tee'd together on 72 and 73 fuel
> > injected Auto trans models which seem to be California built cars. The
> is a
> > CA built and Federal . I looked at mine and both ports are after the
> > throttle  plate.
> >
> >  Do I need two for the trans to shift? Or will one do? I cannot find any
> > info on this.
> I don't know. Mine is the same and it's always bothered me, too. I THOUGHT
> one of the ports was in front of the throttle plate, at least at idle, but
> I haven't
> spent any time studying it. I've never seen any info on this.
> I've always wondered if there was an orifice somewhere in the conductance
> between those two ports, but I've never taken anything apart.
> On mine, one of the hoses wraps over the top of the #2 air runner, and
> time
> has crushed the hose flat there. I've wondered if this means that that
> hose is
> no longer working. Everything still works, except that the 2nd to 3rd
> shifts
> tend to slip unless I'm accelerating hard. No problem with 1st to 2nd or
> on
> any downshifts.
> --
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
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