RE: 1998 O2 sensor

["Mark M. Pikas" <mpikas@umiacs.umd.edu>]

> -----Original Message-----
> From: garwillis@msn.com [mailto:garwillis@msn.com]
> >have both of the 98 O2 sensors mounted in the same exhaust 
> tube after the
> >single cat?
> 
> In this case, I doubt it very much. You're very likely gonna be just
> fine. Reason being, what the ECU is looking for in the 
> post-cat sensors
> is any large correlation between O2 swings in the pre-cat and the
> post-cat. Nuther words, it's *expecting* to see very little 
> signal swing
> in the post-cat. The error condition is when it DOES see significant
...
> BTW, I think you're wise to be planning mounting them both 
> back there on
> the one pipe; that'll preclude problems that might occur if you
> attempted to use just ONE sensor to feed both post-cat O2 inputs. I've
> heard that in some cases this doesn't work, due to how the 
> ECU circuitry
> that reads the sensors is designed. You could TRY using just 
> one, and it
> might be able to drive both inputs and keep the ECU diags 
> happy, but be
> prepared to revert to using them both, if not.

Or you can save yourself all the frustration and hassle and just run some
secondary O2 simulators.  The second set of O2 sensors are there just to see
if there are any changes indicating that the cats aren't working, so the
computer is happy if it always sees the same V.  This is a pretty common
thing to do on '96 and up f-bodies, which also come with 4 when modifying
the exhaust or installing older headers.  I believe that they are made by
Casper Electronics (check the vendors at the bottom of www.f-body.org, I'm
sure that one of them has them).  If you want to build your own, I believe
that they are just a resistor and a harness working as a V divider so that
the PCM always sees something like 130 MV (don't quote me on that but I know
that its somewhere in that range).

Mark
----------------------------------------------------------------------------
To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
in the body of a message (not the subject) to majordomo@lists.diy-efi.org