164S O2 Sensor Hell

["Richard Lasner" <rlasner@domain.elided>]

I took my 92 164S in to a smog test station out here in California last week
and was amazed to find that it was running so rich that it was testing far
beyond the allowable limits. After doing the self-test, and getting a
1-2-2-3 code, the car was gone through to find the source of the problem.
Since the spark plugs, vacuum lines, fuel injection and related parts seem
to check out fine, I'm looking at the possibility of the one-year-old
generic O2 sensor failing. I got it from IMPARTS, whose phone and web site
are now disconnected. Are they gone? I bought an OEM sensor from Alfa Parts
in Berkeley. I'll put it in next week and see what the results are.

As the car is running at around 175 degrees almost all the time, I dialed
back the fan turn-on temp. (I have a Zat Cool Control) to around 215
degrees, and was able to get the code to go back to 4-4-4-4, though it still
tests off the scale for emissions. Using an infrared temp gun, it was
determined that the exhaust temperature before the cat was 325 degrees,
while the post-cat temp was 375 degrees. Anyone have experience with what
the proper pre- and post-cat temp should be? I found a suitable new cat
locally for $500, installed, but I hope that only the O2 sensor is shot, and
that the cat isn't dead. Anyone with personal experience with a similar 164
problem that can offer insight? Thanks in advance for the help. Thanks to
Brad for his off-line advice.

Rich Lasner
92 164S Red
AROC
ARA
Mill Valley CA

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