'91 200q temp/O2 sensor

[tgsgronback@mindspring.com (Steve Gronback)]

I've just completed some tests that should be of interest to at least some
of the listers.  My good friend the Volvo/Honda expert finally had enough
fun listening to me bemoan my poor running Quattro, and took pity on me.  He
has several suspicions in spite of all the work done by the local Audi
enthusiast shop.

First; both temp guages have run low all winter.  The multi function switch
was replaced...waste of money...blank look when I mentioned it didn't seem
to correct the problem...you've heard it all before.  Could it be the
thermostat?

Test; My guy, who wishes anonymity, simply put a laser temperature testing
device on the engine...point and click.  Engine is running 20 to 40 degrees
F. cold.  Seems to cycle the fan at the right temp, but thermostat is not
doing its job.  Took the car out for a quick spin, then checked it again
ASAP-temp right back down to 190 F. or so.

Any one changed a thermostat lately?  Looks like the radiator needs to be
pulled to get at it.  Your comments and suggestions (as always) are greatly
valued.

Second; the car just doesn't run right, and no one until now has had any
success diagnosing the problems (I've ceased hoping its only one thing).

Test; Went right for the O2 sensor with one of those Fluke meters you guys
talk about.  The meter has a guage that gave a readout on a bar graph that
showed the O2 cycling voltage up and down.  Conclusion...slow O2 sensor is
causing computer to mismanage the system.  Instead of quickly cycling in a
medium range of possible voltages, this one slowly seemed to oscillate from
one extreme to the other.

Perhaps the experts on the list could comment or add specifics-I would if I
could.  The suggestion was to replace the O2 with a generic Bosch 3 wire O2.
The wires will have to be spliced, but apparently the one he uses for
certain Volvos is the same except for the connectors.

PS  Best Wishes, Peter

Steve Gronback
TGS Studios
91 Audi 200q
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