Low O2 sensor readings

[Fred Miranda]

Sounds like a ground problem, engine to chassis or exh.

Fred

At 10:18 PM 5/22/97 -0400, you wrote:
>
>I hope yall can help with this one.  Doesn't everyone love a good mystery!
>
>I have been getting a lot of 13 codes on my Monte (O2 sensor fault).  I
>connect a DVM to it and it seems pretty normal, around .4V at cruise, .5 to
>.6 V under acceleration, .3x V or so at idle.  However, at idle in gear,
>when watching the O2 voltage on the DVM, using turn signals make it flip
>flop around by about .15V or so.  Turn on lights, it drops near .30 or .2x,
>turn on AC and blower motor and the O2 voltage drops to .1x volts!
>
>This is wreaking havoc with the computer (CCC), I believe it is retarding
>the timing completely after these codes keep setting.  If I clear them, as
>soon as the system goes closed loop, the 13 code sets again.
>
>I have tested the alternator, it's OK.  Even bolted in a brand new one, same
>symptoms.  Had the battery tested, it's OK.  One thing is peculiar.  At idle
>with everything on, voltage across the battery terminals reads 13.x V.
>Good.  However, the guage on the dash reads more like 10 or 11 V.   I know
>those things aren't perfect, but it reads way low.
>
>Can anybody give me any suggestions on what the problem could be or how to
>chase it down.  I really would appreciate it.  Surely this can't be normal. :-(
>
>Thanks.
>
>Ed Hilker aka "Chief"
>84'SS - 700R4
>
>
>