Date: Mon, 27 Dec 2010 16:47:39 -0500
Reply-To: Ken Wilford <kenwilfy@COMCAST.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Ken Wilford <kenwilfy@COMCAST.NET>
Subject: Re: Progressive rough running - until ignition reset
In-Reply-To: <4D18FB21.3040008@charter.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
John, check out this article I wrote about this exact problem in my
newsletter:
Vanagon Oxygen Sensor Syndrome
Why is my van running like crap?
I have been having so many people call me lately with the exact same
symptoms: Van is running extremely rich, bucking, losing power, and even
visible smoke out of the tail pipe. The van will start up fine and run
well until it is warmed up, then this starts happening. But if you turn
the ignition off and then back on again while driving down the road the
van will start to run good again for a minute or so. If you are
experiencing this problem, I am here to say that I know exactly what the
problem is and I can help you figure it out yourself without spending
hundreds or thousands of dollars at the mechanic. The problem is in the
oxygen sensor system. How I know that for sure is that when the van is
started up, the computer looks at every sensor except for the oxygen
sensor. It uses a built in reading for that until the van warms up. When
you turn the ignition of and back on, this resets the computer and for a
little while it runs off of the built in reading and then switches back
to looking at the oxygen sensor readings again. Now that we know where
the problem is, we can focus our talents on figuring out what part of
the oxygen sensor system giving us a hard time. Grounds. First let's
make sure that we have a good ground from the firewall to the cylinder
head on the driver's side. There should be a strap there and it needs to
be in good condition. If not, fix this first. Next there should be a
ground connection that is coming out of the wiring harness that goes to
the distributor and is also is grounding on the driver's side head in
the same place as the ground strap. If you trace the wiring that goes to
the distributor hall plug back about six to eight inches you will see
this brown wire coming out of the harness. Be sure it is there and not
broken, and has a good end on it and is securely fastened to the head.
If not then repair this.
Oxygen sensor. Now that we know the grounds are good, the oxygen sensor
itself is the next suspect. To test it simply unplug it from the fuel
injection wiring harness. You should find the connector in the area
below the ignition coil. Just trace the wire up from the oxygen sensor
and you will find it. The oxygen sensor is located in the middle of the
exhaust connector pipe for 1.9l Vanagons or in the catalytic converter
for 2.1l Vanagons. If you unplug the sensor and the van runs better then
you need a new oxygen sensor.
Wiring in FI harness. The most insidious part of this problem is that,
more and more, I am finding this problem is caused by the oxygen sensor
wiring inside the main FI harness. That means to fix the problem you are
going to need to replace part of the FI harness itself. If you have done
the other tests and you are still having problems then most likely it is
with the oxygen sensor wiring inside the Fuel Injection harness (aka
engine harness). It is a coaxial wire that has an inner signal wire and
an outer shield. Over time the insulation between these two breaks down
and now you are getting bad oxygen sensor readings sent to the computer
even though everything is fine. You can check that this is your problem
by unplugging the ECU from the ECU plug. In the 1.9l Vanagon the ECU is
behind the driver's side rear tail light in the engine bay. In the 2.1l
Vanagon the ECU is under the rear seat. Over to the driver's side you
will see a black metal box. Take it loose from the firewall and flip it
over and there is the ECU. Unplug it and look at the plug. You will see
a small phillips head screw on the back side. Take this loose and cut
the tie wrap that holds the plug to the harness. Now you can take the
plug apart. You can gently pull on the center section of the plug while
removing the cover. Once the cover is off, if you look at the plug more
closely you will see it has numbers on it. For the 1.9l Vanagon you want
look at pin number 5 or for the 2.1l Vanagon you want to look at pin
number 2. This is the oxygen sensor signal wire and it should be green
in color. Leave an inch or so and cut this wire. Tape the short end up
and put the plug back together. The van should run great now with no
rich running or bucking. You can run it like that forever. The oxygen
sensor just fine tunes your mixture to give you best fuel economy.
However many people are going to want to fix this right. We are offering
a kit of wiring that you can just plug into your ECU in place of the
wiring you just cut that will repair the problem permanently. The kit is
$59.
On 12/27/2010 3:46 PM, John Rodgers wrote:
> Volks,
>
> I have a general Vanagon troubleshooting question - today driving home
> from an enjoyable Christmas gathering with all my family, the van
> engine started twitching - a little skip at first, then as the miles
> rolled it got worse and worse. I was sweating getting home in all that
> snow and rain and raw weather we were having, and sure as heck didn't
> want to stall out and spend time on the side of the road in that
> weather. I managed to make it off I-65 at the southern exit onto Shelby
> Co 25 on towards Columbiana. By the time I got to the last hill just
> outside town - I was down to about 10 miles an hour, and coasted down
> that hill into town to the main stoplight. The plan was to go through
> the light on green, and pull over in a BigBox store parking lot. Didn't
> get the chance. Light changed, and the engine stalled. I turned off the
> wipers, the heater fans, and the head lights, shut off the ignition, and
> then hit the switch again. She fired right up, purring like a kitten. No
> more trouble......... until well up the road. Same thing over again.
> Just a little twitchy at first, then got progressively rough. This time,
> while coasting, I turned the switch off, and back on. The engine cleared
> it throat, and purred like a kitten. Did it twice more before I got home.
>
> So - what could be happening that turning the ignition off and back on,
> results in temporary clearing the problems. At first I thought fuel,
> then some king of ignition trouble, then an electrical fault for sure.
> Electronics somehow.
>
> Any ideas??
>
> Thanks,
>
> John
>
> --
> John Rodgers
> Clayartist and Moldmaker
> 88'GL VW Bus Driver
> Chelsea, AL
> Http://www.moldhaus.com
>
--
Thanks,
Ken Wilford
John 3:16
www.vanagain.com
Phone: 856-327-4936
Fax: 856-327-2242
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