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

Tue Oct 1 15:37:13 PDT 2019

I'll reply to both posts here. I didn't have the engine running when I
pulled the hose between the AAR and IAD . I had the engine off, just wanted
to see what position the valve was physically  in. When I adjusted the +/-
on the spring to get it to close sooner it's was easy to see which way
would cause it to open sooner. On the electric AAR there is a roll pin in
the lower shaft that fits through a slot that is fixed to the metal base.
To remove the valve once you get the lower heater can off and the upper
elbow to connects to the oil bath the pin has to line up in that slot to
pull the valve out. On each side of that roll pin when the valve is
installed there is a stop . It's a pie slice shape so the valve can only
move a certain amount either way. It's the roll pin and the stops that will
not allow you to get the spring on wrong, it will only fit one way. I'll
find the link to the photo's on Samba .

 On being Rich or lean , yes I realize it's the ratio of fuel to air. Yes I
am assuming that when the engine is cold and cold is dependent on ambient
air temps , it seems since TS2 is say 2300 ohm it's signaling the ECU
through some circuit to add more fuel to air, the AAR just adds more air, I
felt ok TS2 is telling the ECU to hold the injectors open a bit longer more
fuel to keep the mix or ratio balanced the AAR is the added air . Somewhere
in all this TS1 does it's little signal  on the fuel end to the ECU . With
the throttle closed the AAR is the only source of additional air to what
ever amount of fuel the ECU based on what both temp sensors read tell the
ECU to hold the injectors open a bit longer.

 I've been told most TS2 units when the engine is hot drop to 75 ohm or
below and the ECU can't see below 100 + ohm. I've been told , I don't know
this to be true. I know my TS2 dropped to 65 ohm after a 45 minute drive on
a 75 degree day and TS1 was 120 ohm , I left the engine running to check
TS1 and checked TS2 as soon as I shut the engine off . I know by that time
the AAR was closed shut.

 I drove the car today 4 mile round trip . Yesterday I gave the MPS another
16th turn now it's near a total of 3/8s turn from the start point. I
started it and it did not climb to 1200 RPM is read 1000 and dropped to 800
in drive. Drove the 2 miles shut it off for 5 minutes still 1000 and 800 .
The next 2 miles back stopped at the post office let it idle. Then drove
1.5 miles to rite aid it was off for about 30 minutes when i started it it
was at 800 RPM in park . the extra heat with it off would drive the sensors
lower less fuel to air AAR was closed . I have read about the TS1 after
shut down going lower causing it to run crappy for a bit yet this flies in
the face of the ECU not seeing resistance less than 100 ohm. I felt this
affect on a 10 mile drive 85 degree day after it sat for over 30 minutes
and it ran crappy for a bit then cleared . I've read about a 150 ohm
ballast in series with TS2 yet read this was for cold weather Russ Wolfe
posted this long ago.

 I have no idea why the idle was low today after it sat for 30 minutes
unless it was TS1 , it didn't run crappy the idle was just low and came
back . Before I only had TS2 in the mix and it ran crappy for about 5
minutes.

 Before 2009 I had none of these issues it ran as you described your 73
does. It ran fine with the original engine that I know had at least 88,000
miles on it before the odometer quit it probably had more miles unless the
engine was changed yet I didn't see any evidence of that yet I have no
idea. It had a X case and everything was there and looked original , all
the seals were dried out still had the red hoses from heads to oil bath.
Once I changed all of that and found the VR was just rust inside causing it
to run on/off rich black smoke out the exhaust it ran perfect. I could see
who ever owned it was not big on oil changes. It ran great from 86 to 97
then the engine was quiet one day the next I started it and it had this
loud internal rattle . I tried to pin it down to the cooling fan or cam
gear rivets nothing wrong there and it still ran great for another 4 months
until I rebuilt the 72 U engine . I used the same MPS the D and it ran
great. this engine only has 36,000 on it and 22 years since I rebuilt it .
I replaced all the gaskets and hoses three months ago because I was told
they were old and they were. It was determined it was vacuum signature that
changed via engine wear which in turn changed what vacuum the MPS saw.
Can't imagine that the old engine had the same vacuum signature as as the
original one did. Yet with the same MPS and all new seals and lines and
gaskets and a fresh engine all I noticed is it had more power with new
cylinder kits with rings had to have higher compression plus it had flat
top pistons and the heads I had done.

 Now I'm lost. I read all this stuff on Samba yet to be quite honest the
stuff I read does not reflect why it has these issues now. It might be the
ECU yet it does seem to see TS1 in some respect or why would unplugging it
change things , that does not mean it's not possible . I have no idea how
the ECU works. I think I can rule out the MPS since two that I know hold
vacuum and read what they should on both coils and there is no short to
ground from any of the 4 terminals.

On Tue, Oct 1, 2019 at 1:51 PM Jim Adney <jadney at vwtype3.org> wrote:

> On 1 Oct 2019 at 10:21, William Jahn wrote:
>
> > Yet you said the AAR open or closed , the mixture should be
> > approximately the same. Does this mean it still does have some affect of
> > making the mix richer?
>
> Assuming we're leaving the temp sensors out of this, and also assuming
> that
> the FI pressure sensor and brain are working as PERFECTLY as the
> designers hoped, extra air at idle should not make the mixture leaner or
> richer.
>
> Look at it this way:
>
> Extra air + the right amount of extra fuel = no change in richness.
>
> Less air + the right amount of fuel reduction = no change in richness
>
> > Yet you said " If the idle changes significantly, it means that less
> > air is getting thru the AAR. The amount of idle speed change will give
> > you an idea of how far the AAR is open." I'm confused because I find
> > the more air through the AAR there is is when I see the idle change the
> > most.
>
> Yes, I think we may be saying the same thing. I'm just trying to get you
> to do
> the testing in an easier, and more informative way. Pulling off the hose
> between the AAR and the IAD is not something you should do while the
> engine is running, so it doesn't tell you anything about how the AAR is
> changing during warmup.
>
> If you use your thumb, while the engine is running, to see if closing off
> any
> air thru the AAR changes the idle speed. You can do this calmly and
> non-destructively while the engine is idling. This is a functional test,
> looking
> only at what effect the AAR is having. It does not rely on anything
> related to
> how the AAR works or what it looks like inside. As such, it may not
> satisify
> ones curiosity about what's going on in there, but it answers the question
> of
> whether it's working right or not.
>
> If closing that hose causes no change in idle speed, the AAR is closed.
>
> If closing that hose causes a small change in idle speed, the AAR is
> partly
> open.
>
> If closing that hose causes a large change in idle speed, the AAR may be
> fully open.
>
> >  I can see why the Idle air screw does not change the mix yet it is a
> path
> > around the closed throttle valve where the AAR is also a path around the
> > throttle valve , it's just a different path that slowly reduces as the
> > valve closes until it becomes no path , both past a closed throttle
> plate.
> > The idle air screw is fixed once it is adjusted for proper idle speed ,
> > once it is set then it still passes air and the same amount whether the
> AAR
> > is open or closed
>
> This is all correct.
>
> > the AAR is simply additional air needed because of a cold engine with a
> > richer mix because of the TS2  needs more air to run and because of
> > cold thicker oil , it this what you are saying? .
>
> I suspect the problem here is that you're equating more fuel with a richer
> mixture. That's not what richer means. Richer means an increase in the
> ratio
> of fuel to air. The goal of the D-jet system is to keep that ratio
> constant, as
> long as the other operating conditions remain the same. It may not
> succeed,
> but that's what it's trying to do. [I'm talking about idle here.]
>
> That's not to say that the D-jet FI tries to keep the ratio constant under
> all
> conditions. Part of its design is to alter the richness (ratio) depending
> on
> need. It's probably richer under load, and we know that it's richer when
> cold.
> How does it change with RPM? I don't know, but the Bosch folks who
> designed it probably had something specific in mind.
>
> --
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
>
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