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Re: [T3] '69 Fastback purchased

On 4 Feb 2005 at 10:12, Everett Barnes wrote:

> > I don't think the Bentley shows them, but they might be in the info column
> in the FI system check list. Bosch just gives 3 resistances at each of 3
> temps for each sensor.
> >
> Where is this check list?  I did find a value of 2500 ohms in the listing
> for using the FI tester box on the head temp. sensor.  There is no outside
> temperature correlation.

Troubleshooting charts b and c are as close as the Bentley gets. Here's the 
Bosch data:

Cylinder head temperature sensor
	Bosch calls this Temperature Sensor II
	Bentley calls this temperature sensor I

	7 kOhm to 12 kOhm at -10C (+14F)
	2 kOhm to 3 kOhm at +20C (+68F)
	680 Ohms to 1.0 kOhms at +50C (+122F)

Intake manifold (or case) temperature sensor
	Bosch calls this Temperature Sensor I
	Bentley calls this temperature sensor II

	860 Ohms to 1200 Ohms at -10C (+14F)
	260 Ohms to 340 Ohms at +20C (+68F)
	90 Ohms to 130 Ohms at +50C (+122F)

I think they are generally fine as long as they are neither shorted nor open 
(neither 0 nor infinite Ohms.)

> All 4 are firing according to my timing light and a visual check.

Verify by pulling SP wires from the dist cap one at a time. It's also useful to 
pull injector plugs one at a time, too. If pulling a SP wire slows down the 
engine, but pulling an injector plug does not, then you have a leaky injector. 
(Be careful pulling injector plugs; don't pull on the wires.)

> > Make sure that the pressure sensor hose is attached at both ends.
> >
> It's is.  The hose is older but I trimmed the ends so they are tight.  I did
> notice the adjustment screw is not sealed so hopefully no one adjusted it.

The hose is probably fine, but I would assume that the PS has been tampered 
with. Since you found that the pressure was low, I would guess that someone 
tried to adjust both things in an attempt to get it to run. I believe turning 
the adj screw CW should make the mixture leaner. Just turn it a half turn at a 
time; I don't think you have anything to lose.

On that topic, I still plan to set up to recalibrate these. One of our listees 
has offered to send me one 4-pin connector body, which I haven't received yet, 
but I still need a second one. Anyone else got a junk one lying around?

> From reading posts in the archives, it sounds like the head temp. sensor
> makes the mixture richer only when the resistance is higher.  So if mine is
> too low, the car should not be running rich and/or wasting fuel?

That sounds right to me. While other people claim to have replaced many of 
these over the years, I don't think I've ever replaced one unless it was 
mechanically damaged.

Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA

List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org

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