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

[William Jahn]

The D unit is a 311 906 051D/ 0 280 100 101 , it's the exact same unit as
the 311 906 051E/ 0 280 100 116. Both have the same nose and have no full
load enrichment in the MPS and no slots in the cover and both have the
black plastic cap and the ground wire tab which none of the others had. If
one were to remove the numbers one could not tell the D from the E . When I
installed the E it didn't change how it ran at all.

 I had this D unit on this car for years and it worked fine even passed
smog in 97.

 You may be right in that it's covering up another issue. The one thing I
noticed once I adjusted it that is different than unplugging TS1 is it no
longer has the issue when I gave it gas when the idle was 1000 then climbed
to 1200 which I thought was a sticking throttle because fixed that didn't
stop the RPM hang . this did. I need to drive it today to see how it starts
cold and how it drives once hot and how the idle reacts. Once I do this I
will report back , as you say it very well could be an ECU issue in the TS1
circuit the only thing about that is the sensor read proper and it does
change  things quite a bit plugged in and unplugged so it seems like the
ECU see's TS1 in some respect.

On Mon, Sep 30, 2019 at 11:12 AM Jim Adney <jadney at vwtype3.org> wrote:

> On 30 Sep 2019 at 10:17, William Jahn wrote:
>
> >  I have a spare MPS 311 906 051 D that used to work fine. I decided to
> > clear out the epoxy locking the one 7 mm allen adjustment screw .
>
> The D should have a slotted screw adjuster, with 2 more adjustments
> beneath it. There are 3 adjustments total in that version, as well as in
> the C
> version.
>
> >  I did not want to screw with the E mps the 116 it is still from the
> > factory adjustment yet felt the D since it's the same exact unit as the E
> > and did work fine before all this . If one removed the numbers from the E
> > and D MPS you cannot tell one from the other.
>
> Those 2 should look quite a bit different. Perhaps you're talking about an
> early E, a 016, as used in '72. That would look exactly like the 116. The
> D
> has slots in the cover and looks quite different.
>
> >  I know adjusting the MPS is done by some in the know yet I tried it and
> so
> > far things are much better with the slight adjustment and TS1 connected.
> > 1/8th turn in not much and I didn't ruin the E116 MPS .
>
> If you stick to less than a half turn, and keep careful track of your
> starting
> point, you're probably okay. You're turning the adjusting screw CCW, which
> is the correct way to make it richer. 1/8 turn, or less, at a time, is the
> way to
> go.
>
> I'd still like to see you try different 116 MAP sensors and different 048
> brains
> to test your original parts by substitution. Changing the MAP sensor may
> cure your current symptoms, but it MIGHT just be doing so by covering up a
> problem in the brain. In other words, it might be the same as unplugging
> the
> temp sensor.
>
> --
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
>
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