[T3] 73 auto trans type 3 ARR ?

Mon Jun 12 11:11:11 PDT 2023

 I was thinking about this idle speed problem last night. I went through
what I thought it might be and then I still don't feel I have found the
problem.
Just because the timing did return to the base setting and then advances
does not mean the distributor is hanging. It could still be a vacuum leak
or any number of issues.

 All I have ruled out so far is the AAR does close once driven because
running I felt no change in the idle speed blocking off the oil bath hose.
I don't see any suspect hoses or lose connections. I could not change the
idle by moving any vacuum hoses and I am willing to replace all of them
again.

 I did replace the intake gaskets with the proper ones and recall when I
did that I forgot to torque the left side #3 & #4. Ionly drove it a few
miles and checked both sides again and found the right side needed a bit of
a re torque just 1 ft lb so it was not loose.

 Now I am not sure where to go with this. I do know it does not miss fire
and the MPG has not changed. It accelerates fine with no bogging or
hesitation. No bucking. It starts fine , the only issue with that is the
start after it sits for a day then I need to use the primer switch to wait
until the air is purged and it fires right up. Once it starts it will start
all day long no issue.

 I thought of the TPS. All I know is it is adjusted properly and I hear all
the clicks , since it accelerates smoothly I have to wonder at idle is it
possible for it to cause this. I've never run across that before. Only know
if it is adjusted wrong it won't idle well. I do have two I got from
George/Tram along with a few MPS of the same type as the one on this car ,
not the same part number but I used one before that was the same type wrong
number and it worked just like the proper one.  I have 2 ECU he sent that
are not the right number. Also a good wire harness from an earlier year
right before VW added the EGR system all it is missing is the EGR circuit
which I don't need. And it has all the plug boots, all of mine are either
missing or barely exist.

Some history.
 To be quite honest. When I decided to replace all the lines and gaskets I
was after an issue chasing an erratic miss. that I could only feel and hear
at idle . If I was near the tail pipe I could hear it as well as feel it.
The only thing that stopped it was to disconnect the IAD temp sensor. I
went down the road of adjusting the MPS I had in the car at the time , the
wrong number of the same exact type and was told to get the engine hot and
plug in the temp sensor and adjust the MPS till the miss stopped. I did and
it worked but not long after it would not start . I had the proper one on
the bracket from before I never tampered with and the test one held with
one bolt on the same bracket . All I did was move the connector and vacuum
line back to the proper one and it fired right up . The one I have on it ,
the proper part was brand new and not even tarnished.

 To attempt to explain the erratic miss. It was not one cylinder , it was
random and affected all . I could not isolate it by pulling a plug wire. If
I had the engine running, trans in park and gently gave it gas the RPM
would rise up and down by 100 RPM , even if I held the pedal steady it
would do the same thing. The only time the RPM would offer a smooth
transition was when it was past the 2500 RPM mark then pressing or holding
the pedal the up/down idle would cease. And the same thing the miss felt
and heard at the tailpipe.

 Point is with the last bit of ramble is changing all those hoses and
gaskets and everything else I did, did not change one tiny thing. It did
not run any better or idle any better . The fix was to unplug the temp
sensor.  I felt better doing this job because all the hoses and seals were
long overdue and the 4 runner hoses were oil soaked and just plain old.

 I am fine with that temp sensor unplugged , I have read with it unplugged
the mix richens up by 10% , this was proven by adjusting the MPS , I turned
the one allen head screw adjustment toward the richer end.  I am not going
there again.

 Now all I have to do is find out what is causing this insane idle speed
and being that it is in a sense intermittent all I can do is try to pin it
down and if it means trying the simple parts first to see, it becomes a hit
of miss and not the way I prefer to do things. I do have a good
understanding of how this system works . It's just a difficult simple
system that there is no tool to diagnose other than electrical tests and
visuals..

On Sat, Jun 10, 2023 at 11:23 PM <jadney at vwtype3.org> wrote:

> On 10 Jun 2023 at 16:46, William Jahn wrote:
>
> >  I got new Intake gaskets from you Jim. I did this work at the end of
> 2019
> > . I cleaned everything and even sealed the IAD back cover gasket using
> > silicone on both sides. Let it set up the 4 bolts loose then when dry
> > tightened them. I replaced every vacuum hose  and the injector seals and
> > all the fuel line . I made certain the IAD lined up perfectly with the
> > runners , and had to bend 2 slightly.
>
> Okay, sounds like you've got all those things covered.
>
> Have you checked the tightness of the two screws for the cold start valve?
>
> How about the hoses for the AT vacuum modulator?
>
> Does your engine still have the EGR valve and plumbing? If so, have you
> blocked it off?
> Checked the short hose that connects the 2-piece pipe to the IAD? (I made
> a blockoff plate
> for the flange to the EGR valve inlet and sealed it with one of those tiny
> VW metal manifold
> warmup gaskets. The heat exchanger also got a blockoff plate and gasket.
> My EGR filter fell
> apart and has been completely removed.)
>
> You could try flushing out the idle air channel with something like WD-40.
> And check the
> '72-3 crankcase breather that vents into the IAD cover; could there be
> something intermittent
> there? (Flush the breather port in the cover and the PCV valve in the
> breather box with
> WD-40 to make sure they're not clogged with gooey oil.)
>
> Keith's suggestion of looking for a leak with an unlit propane torch is
> always something to
> consider, but I've always found this to be hard to interpret. Maybe I've
> just never come across
> a large enough leak.
>
> If all those seem okay, yeah, maybe there's a problem with the
> distributor. You should be
> able to see if the timing always comes back to the same point at idle with
> a timing light, but,
> again, that's hard to interpret, since the timing SHOULD change between
> 800 and 1400
> RPM. Maybe you can just watch how it moves as you move the throttle and
> RPMs up and
> down.
>
> --
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
>
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