Subject:                              Time:  10:14 AM
  OFFICE MEMO         Other O2 Options?                     Date:  11/5/95

At 90K+ miles, it appears to be time for me to replace the O2 sensor on my '89
Syncro, according to VW's mainenance recommendations.  It passed our CA smog
check with no problem a couple of weeks ago, but it idles very rough and won't
hold consistent RPMs at mid-throttle - dips, weaves, hunts around.  So before
I start digging deeply into the FI system I thought I'd at least take the
no-brainer approach first and follow the recommended maintenance by plugging a
new O2 sensor into the catalytic converter.

That is, it was a no-brainer until my VW FLAPS quoted me $120 for the sensor
and the shop across the street quoted me $65.  My suspicion is that this
represents the difference between the special VW sensor (Bosch part
#0258-003-913) and a generic 3-wire sensor (type 13913?).  

My VW FLAPS, of course, claims that the parts are *not* interchangeable, and
that they see Vanagons that have been retrofitted with the generic parts that
have their CO all out of whack and won't pass smog.  However, a note from Jim
Macklow (macklow@sybase.com) in the Bosch-Fuel-Injection FAQ in our Vanagon
archives *does* mention use of a Ford/Mercury O2 sensor that had been sold to
him as VW-compatible (only the plug was different - I think you have to solder
it in yourself) for -yes- $65.19.  He doesn't mention how well it worked,
though.

SO, the question for my esteemed fellow Vanatics (or did we decide on
Vanagonians?) is: Are these two O2 sensors really interchangeable and what
kind of FI Hell am I descending into if I try retrofitting the cheapie part? 
No doubt *someone* one the list has had to deal with this one before - it's
the same part on all Digifant exhausts ('86 - '91).

I'd also be interested to know if 1) Do I really need to replace this part if
my CO emissions are nice and low already, and 2) Am I being naive that aging
of this part could be contributing to my poor idle performance?

Thanks in advance for all the *great* feedback I know I'm going to get on this
one...

Steve Hoge
'77 Loaf         (Da Rust Bucket)
'89 Syncro GL (Da Stutter Bucket)