Emissions....

[Eric Storhok <alfa@domain.elided>]

All the advice has been good answering the question to get close.  There 
are two things that get warm when running hot, the engine and the 
catalyst.  Oviously, the catalyst is more important...  I was under the 
impression that the proper way to do the test was on a fully warmed engine, 
but then again, I do not live in California and don't know the rules.

As for the O2 sensor- when new, its .2-.8, as it ages, it will be .35-.65 
and sort of work.  But it will work...  If you have a dead O2 sensor, more 
than likely, you will see <.2V all the time.

And the temps, I'm not sure on the skin temp.  But on the differential, if 
the outlet is hotter than the inlet, the cat is working just fine.

Anyway, based on what you say, I'd guess that the catalyst is partially 
dead.  You don't report any serious drivability problems, so perhaps the 
sensor is somewhat working.  On a car that old, especially an Alfa that has 
a tendency to burn oil at high milage, It's highly likely that the catalyst 
is coated with Phosphorus, which is the most common catalyst poison these days.

I will note that if you can rig it up, a 3 wire sensor will be better, as 
it will be hot all the time, and make sure the whole system is working in 
closed loop mode all the time.

Good luck!
Eric Storhok
Ann Arbor, MI



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