[T3] Temp sensor and MPS problems on new motor

Jim Adney jadney at VWType3.org
Sat Feb 27 14:33:49 PST 2016


On 26 Feb 2016 at 19:32, Jessica Chase wrote:

> We haven´t had a chance to make much progress on our FI system issues,
> but we have a new brain on the way. Also, Daniel has been taking
> resistance measurements of our TS2 (head temp sensor) after the motor
> has warmed up, usually at either end of his commute. In a week where
> temps have ranged from the low 30´s all the way up to 60, the
> res?stance readings have ranged from 90 ohms to 79 ohms. These are
> pretty low readings from what we gather, so our next move will be to
> ballast the sensor. 

I would just leave it alone. People make WAY too big a deal about the 
exact value of this.

> After work today, Daniel went through 4 tries at starting but on the
> 5th try nothing happened. The idiot lights came on but the starter
> didn´t spin around. He had to push start it to get home. After the car
> got home, it fired up no problem after being parked. We had a problem
> with idiot lights but no starter over the summer on a really hot July
> day after a long highway drive. Today, the car had been off for 6
> hours and it was 33 degrees out! ItTMs a little confusing. W?at do you
> all think? 

There are 4 things that I can think of that can cause these problems:

1) Starter brushes worn out: replace. I have brushes, but you have to 
tell me which starter you have and whether it has 2 or 4 brushes.

2) Starter brushes sticking in their guides: open the starter and 
clean out all the brush dust.

3) Braid from solenoid to starter corroded thru: replace.

4) FI wire 18, which goes to the starter solenoid, has to pass around 
or thru the engine "firewall." If the insulation rubs thru there, it 
can short to ground and short the incoming voltage from the ign 
switch also to ground, rendering the starter inoperative. This can be 
intermittent. You can tell this mode by noticing that the idiot 
lights go out when the key goes into the START position. This 
happened to me on my '68 MANY years ago; I fixed it by installing a 
rubber grommet in one of the firewall holes there and then running 
that wire thru the grommet.  

4a) If that wire is connected, by accident, to a terminal that is 
always hot, it can't keep the starter from working, but it will make 
the engine run rich all the time.

Last week I suggested that you unplug wire 18, the pressure SWITCH, 
and the TVS. The car will drive perfectly normally most of the time, 
but the idle may be a bit strange and it won't have as much power 
under full throttle. It's just a way to eliminate those 3 items from 
your troubleshooting. I recommend that you do these 3 things, but 
just as a test.   

> Then, we were driving together and heard a strange moaning sound from
> the area of the motor. I thought it might be because my bike was in the
> back and was picking up some vibrations from the motor but no dice.
> Even with the bike out there was a moan. I turned off the headlights
> after parking and the moan went away. When I put the lights back on,
> the moan came back. It seemed to very clearly be coming from the
> generator. Are we crazy, or is this a thing that happens? 

Sounds like it's electrical demand driven, which seems odd. I don't 
think I've ever come across that, but I'd check the generator pulley. 
Feel down in the groove in the part where there is no belt and all 
across the face of the pulley. You're feeling for annular cracks in 
the pulley. I'm trying to think of something that would make more 
noise when there's more tension in the belt. It could also be just a 
belt that's worn rough on the undersidef, or even a bad bearing.

When you adjusted your pressure sensor last week, which way did you 
turn it and how far?

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