Hi Joe,

Have you tried running open-loop(i.e. 02 sensor disconnected)? It sounds
like it might be stumbling when it goes into closed loop.

Mark Ingalls
85 GL

>From: Joe L <mejoe@EMAIL.TOAST.NET>
>Reply-To: Joe L <mejoe@EMAIL.TOAST.NET>
>To: vanagon@GERRY.VANAGON.COM
>Subject: Sing: All I want for Christmas is my Westy back!!
>Date: Sat, 22 Dec 2001 12:31:18 -0500
>
>         After running fine for the longest time my 83.5 (Water Cooled)
>Westy is
>suddenly sick. The troubles came on quickly and without any warning signs I
>could detect. One day fine, the next BLOOOOEY!! I was going on a  short
>trip
>and was just pulling away from the house and accelerating through the gears
>when, without warning, the  engine bogged down and quit. Thankfully it quit
>at the end of my block so no tow was needed but I did have to push  it back
>to the front of my house because it simply refused to start.
>
>         The next day I went out to try to see what was wrong. It started
>right off.
>With the transmission in neutral I worked the gas pedal to see if I could
>detect anything unusual in the way the engine sounded or ran. For about a
>minute or so from the "dead cold start" it ran fine and "rev'ed" without
>complaint, then came the troubles. There was some new "bogging down" or
>"stumbling" at the very beginning of the  throttle travel just above idle.
>This "bogging down" did not occur every time but often enough to let me
>know
>that  it was not a "fluke" and that "something", "somewhere" was wrong with
>my baby. There was also an occasional muffled back-fire that came, not from
>the tailpipe, but from the area of the air cleaner. With the engine running
>I took a quick look in the engine compartment to see if there was anything
>obviously wrong like a disconnected  vacuum line. It was just a quick
>once-over but I saw nothing.
>
>         At this point the engine had been running for about 15 minutes
>and, except
>for the above mentioned  "stumbling" was running fine.  I decided to take
>it
>out for a short drive to check symptoms with the engine under load. Pulling
>out from the curb, as soon as I put it in second the engine "bogged down"
>and quit.  While coasting to the side of the road I tried a restart. It
>started, ran rough for a couple of seconds and again  quit. I tried a few
>restarts but during these the engine refused to start at all.
>
>         I sat on the side of the road for maybe 5 minutes working up the
>ambition
>to push it back to the house. Just  before climbing out to begin the push I
>tried one last time to start it, this time it did. I drove it to the end of
>the block, turned around and headed for the driveway while I still could.
>My
>baby was obvously struggling but she made it.
>
>         Pulling back into the driveway I put it in neutral and worked the
>throttle
>as before. That same "stumbling" slightly above idle speed showed up along
>with occasional muffled "backfire" that seemingly came from the area of the
>air filter. She has been in the driveway ever since.
>
>         Since then I have replaced the fuel filter, plug wires, rotor,
>cap, temp
>sensor II (the one in the thermostat housing) reset the idle speed and
>timeing. I also replaced every "thin" vacuum lines I could see (Any
>"obscure" vac lines hidden deep that amatures usually miss?); all without
>decernable effect. I have noticed that from a dead cold start (first of the
>day) she will seemingly run fine and will "rev" without complaint but a
>couple of minutes into the warm-up and the troubles arrive.
>
>         Rather than continuing to throw parts (and money) at her I appeal
>to the
>collective wisdom of the list for help.
>
>         Any hints/help/advice is MUCH appreciated. It's a drag having sick
>"kids" at Christmas.

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