I had the exactly (and I mean exactly) the same problems as you on my
90 Westy.

My fix (after many, many sensor changes) was to run a new O2 ground
wire from the ECU connector back to the engine and grounded it on the
engine.

Laurence Smith
Hamilton, ON
90 Westy (fanumbos)

> -----Original Message-----
> From: Vanagon Mailing List
> [mailto:vanagon@gerry.vanagon.com]On Behalf
> Of Mike Finkbiner
> Sent: Tuesday, March 19, 2002 11:09 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Cough, Choke, Splutter!
>
>
> I am having an interesting problem with my '87 Westy.  I
> drove about 300
> miles to Seattle, getting about 14 mpg, significantly worse
> than I normally
> get.  When I got off the freeway and started trying to find
> a parking place,
> the van started running rough, loosing power, and trying to
> die. I parked,
> and went into the bookstore I had come to, figuring I would
> let it cool down
> and see how it was running then.
>
> After an hour I came out, started it up, and it ran OK.  A
> few minutes
> later, though, it started acting worse than before, no
> power, wouldn't
> accelerate, engine pulsing, backfired.  I managed to pull
> off the street,
> and checked my digitool.
>
> The O2 sensor, which should have been running around .5
> volts, was, IIRC,
> over 9 volts (!), so I moved the stuff out of the back,
> unplugged the O2
> sensor, fired it up, and things ran fine.  I figured I must
> have a bad
> sensor, or a wiring problem, and hoped I could run it in
> open loop until I
> got home.  The digitool reading was now .35, which seems a
> bit low for the
> default setting.  I thought it should be about .5.
>
> Things went OK for the next 100 miles.  Gas mileage was
> better, and the van
> ran OK.  Then, in a pouring rain in slow moving traffic, it
> started losing
> power, and trying to die.  I re-started, and things went OK.
>
> The next 180 miles was some city but mostly freeway.  The
> van ran fine, but
> only got 13.5 mpg when I filled up in Seattle.  I headed east over
> Snoqualmie, and it seemed to have reasonable power, but
> still only 14.6 mpg
> when I filled up in Royal City.
>
> I stopped for dinner in Othello about dark.  When I got out
> and headed out
> of town, it was just like the time in Seattle, engine
> pulsed, wouldn't
> accelerate, kept wanting to die.  Backfired a couple of
> times. The engine
> wouldn't keep running unless I kept my foot into it.  While
> stopped at a
> light, I did see a cloud of dark smoke come from the back
> of the van.  Each
> time I re-stared, it would run OK for a short time.  I
> poked and prodded,
> couldn't find any obvious problems, so spent the night there.
>
> Next morning I got the multitester and looked for ground
> problems - didn't
> find any.  No obvious disconnected wires, except the O2
> sensor, and no loose
> vacuum lines.  When I warmed it up, things ran fine.
> Couldn't make it act
> up.  So I headed home, and in that stretch got 13.8 mpg (Ugh!).
>
> After I unloaded, I reconnected the O2 sensor, to see if
> that would cause it
> to malfunction.  No problem.  The digitool readings were
> bouncing up and
> down around .5.  The van ran fine around town.  Ran fine
> this morning going
> to work.
>
> Coming home for lunch, the digitool readings for the O2 sensor were
> negative, -.1 / -.2 or so, until it warmed up a bit.  When
> I got home,
> idling in the driveway the readings were negative again,
> -.15.   After
> lunch, I had a milder episode of the same problem.  No
> backfiring, but no
> power, wouldn't accelerate.  I pulled over, disconnected
> the O2 sensor, and
> it ran fine.
>
> The throttle position switch indicator light comes on when
> it should.  The
> AFM seems to give the same sort of readings it usually
> does, no jerking, but
> I haven't had it on that setting when I have had problems.
>
> Seems to me that there are several potential sources of the
> problem -
>
> 1) I did not dance widershins around the van before leaving
> on the trip
> 2) The wiring to the O2 sensor has an intermittant short or ground
> 3) The ECU is going bad
> 4) The digitool wiring is causing a problem
> 5) Something else
>
> The ECU is a two year old Bosch.  The Temp II sensor was
> new last summer.  I
> have the wiring harness on the AFM, and have cleaned the
> wiper path.  The O2
> sensor is a Bus Depot generic, about two years old.  The
> one it replaced was
> also soldered, and the wiring that connects it to the
> wiring harness near
> the coil looks worn.
>
> The fact that it re-starts easily, and run OK for a brief
> time afterwards
> indicates that it's some sort of sensor problem, or a
> problem with the way
> the ECU is dealing with signals.  Re-setting it by turning
> it off will solve
> the problem until it settles down.
>
> I hate intermittant problems like this, and am not sure how
> to figure it
> out.  At first I hope replacing the O2 sensor would do it,
> but after it
> acted up while in open loop, it doesn't look like it.
>
> The 9 volt reading I think I saw in Seattle worries me.  If
> it had a partial
> short through the wires, could that have damaged something?
>
> Any suggestions for things that could be causing these
> symptoms?  I thought
> if the O2 sensor was grounded or shorted, the ECU would
> just go to open
> loop?
>
> Thanks for any suggestions!
>
> Mike Finkbiner
> '87 Westy
> Moscow, ID
>
>
>
> Mike Finkbiner
> mike_l_f@hotmail.com
>
>
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