Lamba sendor readings - advise needed

[Quinton McCombs]

I have been having a problem with my Mazda Rx7.  I have posted this message
to the Rx7 mailing list a few weeks ago but no one responded.  I was
wondering if someone on this list could give me thier thoughts.

I have had a problem for the longest time from running too rich.  I
connected a digital volt meter to my O2 sensor to get some readings and I
have seem some very strange behavior.

First when the car is at idle (about 1K RPM), the O2 sensor normally reads
around .85v.  As I continue to idle the voltage will drop at ablout a rate
of .01 volts per 5 seconds.  I am assuming that the exhast temp is just
cooling down.  I have not monitored it long enough to see what it settles
down to.  After about 5 minutes it wil settle around .65v.  Is this a
correct assumption?

Next, I seems to been running lean intermittantly.  I finally figured out
that any electrical load on the car (head lights, brakes, fan, power
windows, etc) will cause the O2 reading to drop by .02v - .03v almost
instantly.  Now I am not sure it the O2 readings are accurate at all.  Any
idea what could be causing this?

Finally, I have noticed a strange problem which appears under full load at
>6k RPM.  The car acts like it hits fuel cut for about 1 - 1.5 seconds.  I
noticed that when this happened by O2 reading dropped from around .83v to
.65v.  Just after the car picked back up, the O2 reading went back to .85v.
 When this occurred I was running approx 10PSI @ 6500 RPM 3rd gear.  I have
a PFC FCON with a fuel cut defensor.  Other mods as well, but these are the
only ones that I could see affecting the fuel delivery.  Ideas?

Also, what are acceptable readings from the O2 sensor under full trottle,
crusing, idle, and deceleration?  Under full throttle I will run anywhere
from .91v to .83v.  Level ground maintaining speed voltage is anywhere
between .30v and .65v. Very slight acceleration .80v - .85v and just
slightly more will drop it to .75v - .80v.  Idle is around .82v - .85v (for
a little while).  Deceleration will drop to very small negative voltage (I
want to say around -.025v range).