Hi Earl,

Wow! 27 MPG!?! In a Vanagon???

Did I miss some of this thread? Is yours a deisel?

tony

----------
> From: Earl Smith <earlsmit@islandnet.com>
> To: Multiple recipients of list <vanagon@lenti.med.umn.edu>
> Subject: 84 dont smoke no more
> Date: Tuesday, April 29, 1997 2:26 PM
> 
> 
> >
> >The story so far:  about two months ago a sudden increase (or should it
be a
> >decrease?) in mileage from 27 mpg to 10 mpg. About a month ago, increase
of
> >about
> >ten thousand percent in black smoke emission.  (Sure discourages
tail-gaters!) 
> >Lots of excellent advice and suggestions from you folk, change of ECU
and Temp.
> >sensor 2, adjustment of AFM.  Minimal improvement.
> >
> >Friday, finally took it to a mechanic.  It took him three hours to
figure out
> >what was causing the problem and I think it was a great piece of
detective
> work.
> >
> >Wire coming from the O2 sensor on the 84 is a single lead that plugs
into
> >another
> >lead coming out of the wiring harness.  That harness lead goes into the
> multipin
> >connector.  For reasons known only to themselves, VW engineers made that
> harness
> >lead a co-axial cable with the shield grounded.  Somewhere along that
lead,
> >inside the harness, the insulation around the inner wire broke and
allowed the
> >signal to ground on the shield.  
> >
> >The mechanic, Niel, took endless trouble to explain the operation to me.
 Seems
> >at 600 degrees the O2 sensor generates a 0.5 volt signal to the
computer.  Over
> >that voltage indicates a rich mixture and the ECU decreases the fuel
flow.
> >Under
> >0.5 volts indicates a weak mixture and the ECU feeds in more gas.  A
grounded
> >wire will produce a 0.0 voltage so guess what the ECU does?!!.  Niel
simply
> took
> >apart the multipin connector and checked the voltage at the pin, then
cut
> >off the
> >faulty lead and replaced it with a single wire lead.  Now ole Smoky
purrs like
> >a kitten and I am looking forward to 27mpg. again.
> >
> >
> >
> >