this oughta be a stickie.  well mooted, ken.

bill
felton, ca

On Mar 17, 2014, at 2:43 PM, Ken Wilford <kenwilfy@COMCAST.NET> wrote:

> As you are driving and the van is messing up, turn the ignition off and
> then turn it back on (you don't have to engage the starter the engine
> will automatically restart).  Does the van run better for a minute then
> start messing up again?  If so it is a problem with the oxygen sensor or
> the oxygen sensor circuit.  Unplug the oxygen sensor and try driving
> with it unplugged.  The plug is located near the engine coil in the
> engine compartment.  Trace the wiring from the oxygen sensor which is
> screwed into the catalytic converter and you will find the plug.  The
> engine harness side is a thick green wire.  Unplug this and try to
> drive.  If this fixes the problem you can drive the rest of your trip
> with this unplugged and it won't hurt anything, you will just not get as
> good of MPG as if you had a good oxygen sensor.  When you get back home
> install a new oxygen sensor and you are good to go.
>
> If you unplug the sensor and the van is still messing up then it is a
> problem with the oxygen sensor wiring from the plug to the ECU itself or
> the ground for the oxygen sensor wire.
>
> Look at the wiring that is going to the Ignition Distributor.  You will
> see a plug that is on the side of the distributor with wiring coming
> from it.  Trace that back about 6 inches and you will see a brown ground
> wire coming out of the harness.  This should ground on the cylinder head
> on the driver's side.  If you look straight down behind the AC
> compressor with a flash light you will usually see it attached there.
> Inspect this connection.  It needs to be in good condition.  If it looks
> sketchy replace the end.  Also there should be a ground strap going from
> the driver's side head to the firewall just below the coil.  That needs
> to be there and in good condition. If it is really corroded looking or
> just broken you can get a new one at your local NAPA store.
>
> If the ground wiring is good then the problem is with the oxygen sensor
> wiring itself between the end and the ECU plug.  You can repair the
> wiring when you get home, however if you are away on the trip, you can
> do a quick fix which is to cut the wire at the ECU plug itself.
> Unplug the ECU and you will see the plug is held together with a tie
> wrap at the wire bundle and a small phillips head screw on the back of
> the plug.  Cut the tie wrap and remove the phillips head screw. Now you
> can pull the plug apart to get to the back side of the plug where the
> wiring is.  You will see that the plug has numbers on the back side of
> it.  For the 2.1l Vanagon the wire you are looking for is green in color
> and is in location number 2.  Leave about two inches of this wire and
> cut it.  Now put some electrical tape over the end of the wire and put
> the ECU plug back together.  The van will run great all the time
> although you will experience a little less MPG.  You should be able to
> drive it as normal for the rest of your trip and then when you get back
> home you can run a new shielded wire from the ECU plug to the oxygen
> sensor plug and be back to normal.
>
> I have been running into this problem as these vans age the wiring
> harness is degrading.  The wiring to the oxygen sensor is coaxial and
> degrades so that the signal to the ECU, even with the sensor unplugged,
> can be screwy and cause the van to run extremely rich.