>I whiled away 1.5 afternoons this weekend doing the O2-sensor-as-mixture-
>tester trick.  Paid $45 for generic three-wire O2 sensor, $25 for cheapest
>Radio Shack DVM.  Wired so I could power the heater leads from the cigarette
>lighter, and see the voltage display as I drove.
>
>As I had read posts about the idea, I had pictured sticking the sensor into
>the tailpipe (eg on a copper pipe to protect the wiring) but with sensor in
>hand I realized this won't work:  pigtail end of sensor must be in outside
>air for it to work.  I tapped the sensor into a pipe that is a press fit
>into my tailpipe.  
>
>Very educational to watch the display.  "Sweet spot" setting of mixture
>(on 77 CIS engine) is very narrow and has nothing to do with best (ie
>stoichiometric) setting at idle.  I can't imagine pulling the plugs often
>enough to get it right without a tester that can go on the road.  Does this
>match the experience of others -- that CIS system is rich at idle in order
>to be neither rich nor lean at speed?  Or do I need to install clean plugs
>and try again?
>
>B.
>

Nice work!  I'm not sure many others have experience with the O2 sensor, John?

On my Haltech meter, with the apparently very expensive LED's, I was reading
two to three "green" lights, which is about five lights over stoich.  I have
no idea how many volts that is.  This was when the car was running well and
cool.  When I tried to drop the mix down I don't think I got quite the same
performance, either on the road or at idle.  However, I only had one day's
experience with the set-up running so I really don't know.

Eug,