[T2] A/F ratio measurement

[c.dreike]

Howdy Volks,

Spent a couple of hours today with Sami D.  looking at his engine. 
Sami's complaint is high head temps when going up a steep long hill in a 
low gear (am I correct on that?). (kinda sounds like Mike Soultanian's 
problem we heard about a couple years ago. Don't know if he ever figured 
it out)

We set up a wide band A/F sensor on the outlet of the tailpipe with an 
angle bracket and hose clamps. We seemed to be getting reasonable 
readings. 11.8:1 under heavy acceleration and around 12.5:1 under 
lighter loads. This evening I was thinking about this and realized that 
he has a catalytic converter on his exhaust system. Is there a 
difference if we had measured upstream of the Cat? Rather than 
downstream as we did?  Do we have an accuracy problem because of the cat?
Thanks "Brain".

BTW we were able to check compression on cylinders 1 and 3 at 120 and 
117 respectively. Should be OK I would think.

Spark plugs were brand new with about 50 miles on them. Mostly freeway 
driving. Clean as the proverbial whistle. No carbon, the insulator white 
as can be.  Any ideas?

Chris