This is a subject that I have been thinking about and also talking to others
about for a while.  Talked to a guy that runs a business selling Catalytic
Convertors and also Oxygen sensors.  I asked him if splicing the three wire
oxygen sensor was a good idea.  He said "No" because the ECU is looking at
microvoltage inputs from the Oxygen Sensor and a butt splice would cause a
resistance (although a small one) that would make the ECU get false readings
(he called it a "lazy" oxygen sensor).  He said maybe a solder splice would
be acceptable, but I have seen most folks idea of soldering and it ain't
pretty (leave this to the pros).  He said that he only sells direct plug in
oxygen sensors for this reason.  He was not financially motivated in telling
me this since he didn't have any 3 wire Vanagon oxygen sensors to sell.  This
was merely his experience.

So does anyone else have an opinion on this one?  I mean I would love to sell
the cheapy universal 3 wire sensors but not if they are going to cause
performance problems or loss of mpg in a customer's van.  The price
difference is quite a bit though.  The universal (u-splice-it) is $30 while
the plug in oxygen sensor is normally $120 (however I have a special on it
for the next couple of days for $100).  I would actually make more money
selling the universal one but, as I said, I just don't feel comfortable with
this.
Ken Wilford
Van-Again
John 3:16