[T3] Temp sensor and MPS problems on new motor

[Jim Adney]

On 28 Feb 2016 at 21:30, Jessica Chase wrote:

> The belt is a NOS 9.5x1000 Optibelt with only 975 miles on it. It´s
> v-shaped on the underside, has no teeth, and fits really well. We took
> off the pulley and it looks completely fine though the piece that
> slides over the woodruff key comes off quite easily if that means
> anything. Since Friday evening, we´ve gone out of our way to run the
> car with the lights on (even in the daytime) and the moan?ng sound
> hasnTMt come back. What the heck?!?! 

Sounds just fine. What the heck, indeed?

> We had to push start the car again today. It took 5 tries to get it
> started cold. Then, we took a very short drive and after sitting for
> about 45 mins the starter would´t spin. Wire 18 isn´t frayed and when
> we turn the key the idiot lights don´t dim or go out. Any use in
> installing the Bosch hard start relay kit? We have one. Any other
> moves we should make? 

Next time you have trouble, see if tapping on the side of the starter 
fixes the problem. If so, the brushes are probably just hung up and 
need to be freed. They could also be just about worn out. I wouldn't 
bother with the hard start relay just yet. I've never had to install 
one.

> The starter is 311 911 023 B. It was hard to read the Bosch part # but
> it seems to be 0 001 211 012 then the Bosch symbol then 013. We could
> only see one brush, but from this part # can the correct amount of
> brushes be inferred? Oh, and here´s a picture of the starter body and
> another of what the connectors looked like. Altogether quite clean but
> after these pics I polished them up with 800 grit paper and put some
> dielectric grease on everything 

That's probably the original starter, installed in 1969. So it may 
indicate that your brushes need attention. This is a 2 brush starter 
with copper field coils.

> http://images.thesamba.com/vw/gallery/pix/1471142.jpg
> <http://images.thesamba.com/vw/gallery/pix/1471142.jpg> 
> 
> http://images.thesamba.com/vw/gallery/pix/1471141.jpg
> <http://images.thesamba.com/vw/gallery/pix/1471141.jpg> 
> 
> When we adjusted the pressure sensor last week, we went CCW to richen
> it. It seemed that we went too far as the AFR #´s were very rich and
> we got horrible gas mileage. Normally, we´ll fill up every Monday
> unless we go on a weekend trip.

I recommend keeping a log of odometer mileage and gallons at each 
fillup. You can do this in the form of a sort of spread sheet, where 
you have columns for odometer miles, miles since last fillup, gallons 
purchased, and miles per gallon. Keep this in your glove box and 
write down odo miles and gallons each time you fill up. You can go 
back later and calculate miles since last fillup and miles/gal. That 
will give you real numbers to work with.

Gallons per week and days per tank have really ambiguous meanings.

How far CCW did you tweak the pressure sensor?

> Today we disconnected wire 18, the pressure switch, and the TVS. The
> idle was a bit strange. It seemed to wander around a lot and the AFR
> #´s did the same thing. However, everything else was fine. In fact,
> the motor wasn´t underpowered at all. We hit 40 in 2nd gear with no
> problems! The AFR´s here were actually BETTER with everything
> unplugged than with it all plugged in. There was never a number higher
> than 15 for more than a split second. So what on earth does that?tell
> us??? This is getting kind of maddening!! 

So maybe we're narrowing in on something. Drive like this a bit more 
to make sure your problems don't reoccur, then plug one component in 
at a time, testing each one. Find the one that makes things 
misbehave.

Did you ground wire 18? When correctly connected, it will be grounded 
thru the solenoid. Next time you have a chance, measure the voltage 
on the end of that wire for me, with the engine running and the wire 
disconnected. If it sits up around 12-14 V, it's richening the 
mixture while being disconnected. That would confuse this picture.

> With all of our pressure sensors, we´ve noticed that the AFR leans out
> under hard acceleration until the pressure switch kicks in. Then
> there´s uphill acceleration. We could be cruising at 13 but if we have
> to push it up a hill in 3rd, the AFR will spike into the 16´s. 

I don't know normal AFR numbers, but this sounds pretty normal. The 
pressure switch should richen things under WOT. That should be the 
same for uphill and flat driving. The only difference should be that 
flat WOT can only be sustained for short times, while a good hill can 
go on for many minutes.

If your only complaint is that things get too lean under WOT, then I 
wonder if your pressure switch doesn't toggle at the right vacuum. Do 
you have a vacuum gauge that you could connect to your pressure 
switch, so you could suck on a hose and listen to when the switch 
clicks? You would need a length of hose, a Tee, and some time. If so, 
get me some numbers and I'll compare with numbers I get with switches 
here. I have several spares.  

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