Re: V8 O2 placement

[PDQSHIP@aol.com]

In a message dated 95-12-30 17:57:41 EST, you write:

>
>Q1: if the one sensor "H" setup is a nice solution, why then did they go to
>two sensors for the v6 cars?  i can't imagine that two sensors would be
>any cheaper.  or was it done to provide redundancy and longer intervals
>between replacement? 
Prolly cuz the v6 has a single cat.......  Usually the duals are found only
with a twin bank with one cat, but the number is still an average of the two
readings.......  A v6 could benefit from an "H" set up, but I have yet to see
one installed on a car.....   when a O2 can't register each bank, some
serious emmissions regulations comes into play......  But as long as you have
a single lambda freq valve sytem, the redundancy argument applies....
>
>Q2: why are v8s so prone to OXS problems?  is it the OXS itself?  or is
>the motronic system deficient?
My guess is it is the O2 itself.......  But, an O2 sensor is a 40k part max,
and I know there are a lot of 4-ringed owners that more than double/triple
that figgr.......  When I had the Dodge turbo, with the tweeks it would eat
O2 sensors about every 6 months, thank goodness it was a single wire O2 and
cheap.....  But, I could always tell the state of the sensor by idle quality,
with a brand new O2 it was rock steady, with an older one it would be erratic
and actually stall when the A/C on........  The "torque" pipe on the v8 has
prolly the most heat next to the Cat chamber, and this could help warmup
(altho with three wire hookup, I'm not convinced this is a necessity) and
emissions.   The only way to ck it would be to put the O2 downstream in both
pipes just before the cat, but then you get the redundancy argument.......
  I put a 3 wire O2 on my scirocco, and put it way down stream (originally in
the y of the exhaust man), just before the cat, and it worked for 60k before
raising it's ugly head......   

The electronic ignition systems are more sensitive to O2 input than say a CIS
sytem, cuz on a CIS the idle baseline is set lean, then the O2 will add fuel,
which is not the cas with the electronic systems, which means that if the O2
is slow (which is what happens as it goes "bad"), the emissions will be "out"
almost immediately........


Scott