[V8] O2 sensor circuit, rewire from Ecu?

[urq]

Why not follow the wiring loom?  It goes through a boot near the hood hinge.
Since the OXS pin at the engine block broke on one of my cars I may be going
down this path myself.  You might even be able to snake a wire through the
jacket of the factory loom ... I've had success with this in the past with
other Audis.  My plan is to fit a Ford OXS connector myself.  

Rather than running direct wires all the way to the ECU, you might want to
set your sights at the Kostal connectors at the firewall.  This is where the
factory wires go, and it allows the modules to be disconnected the same as
the factory designed.  I can tell you from experience, that it is convenient
the way the engine wiring loom detaches, allowing the engine to be removed
without having to remember where all the wires went.  

Do not use a chassis ground for the OXS.  If you are going to the trouble of
adding this new wiring, do it right and use the engine block for your
reference.  It is probably best to look at the factory wiring as a guide.
The ground for the OXS and the ground for the heater should be run
separately.  It would be OK to attach both to the engine block, just run
separate wires for ground.  

In fact, what you might want to do is to keep an eye out for a wiring loom
from a V8Q ... 

The trip computer issues are probably due to poor connections in the
instrument cluster.  Have you confirmed mileage by dividing miles by
gallons?  

Steve Buchholz

-----Original Message-----

Ok, ok, ok.  I've so had it with this car's bloody emissions system.  So,
after running around for 2-3 days, the trip computer is claiming a dismal
10.5mpg average, with avg speed in the 40s, mixed highway and in town
driving.  It also seems that I'm going through gas pretty quick.  Not sure
how accurate the gauge is, but that is pretty bad.

I've tried the O2 sensor 2 times now, and I'm pretty sure the wiring is just
not dependable.  The first time I went in there, I found the connectors had
been broken off right below the rear of the engine where the air cleaner an
IM meet.  So, I had to get creative and redo all that.  I'm not confident
its holding up well because of the difficulties with space causing my
soldering to be less than optimal.

So, I know I've heard mention of someone testing the circuit at the ecu
connection.  And I've found a great place to route my wiring.  The CAT
sensor's wiring formally resided on the passenger side footwell, inboard
right by the trans tunnel, and just an inch or two inboard of the thick
insulation.  I've removed this sensor and spliced the wiring together to
fool the sensor, so I have that grommet free to route my wiring through the
floor.

So, does anyone know where I need to run my wires?  So far, I think that I
would need to run from the O2 fuse in the pass foot well to the O2 heater,
and then one wire to ground on the chassis (on a 4 wire sensor)  and then I
assume two more wires go right to the ECU, is this correct?  Anyone have the
pins and maybe color/pictures?

Thanks a Lot.
Nick.

P.s.  lot of traffic on the list this week, good stuff.  a bit of it is
mine, hope I'm not bothering anyone with all the inquriys!
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