Date: Fri, 2 Apr 2004 17:35:52 -0500
Reply-To: Dennis Haynes <dhaynes@OPTONLINE.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <dhaynes@OPTONLINE.NET>
Subject: Re: Digitool and driveablity issues
In-Reply-To: <CGEFJBDNAJIKINDGMKEFIEMFCBAA.antelopewesty@adelphia.net>
Content-type: text/plain; charset=us-ascii
I'm not sure exactly what is being measured as the "O2" ground, but if
it is in fact the ground wire (shield), for the O2 sensor or its ground
circuit, that floating .4 volt is your problem. That floating voltage
gets added to the ~.5 volt the system is trying to regulate at. If the
O2 sensor can not generate over 1.0 volt which is common, the ECU will
continue to enrich the mixture trying to get that voltage. The O2 ground
is a separate wire which runs through the harness going to the
distributor pick up coil. Usually, it is connected at the base of the
oil breather tower. Yes, lets use plastic for a connection for something
this critical! What was VW thinking? Relocate this ground and make sure
the wire to it is good. Replace the crimp if needed. I usually connect
it to one of the fuel pressure regulator bracket bolts.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of Kevin
Sent: Friday, April 02, 2004 4:58 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Digitool and driveablity issues
Hi Volks,
I just rented and installed the Digitool computer from Volkscafe. I
email
them with some questions but figured I shoot a copy to the list for more
words of wisdom...
First here are the symptoms of the van. 1987 Vanagon with digifant all
stock
4spd.
Usually when raining or humid (sometimes dry) the van start to surge
and
bog down and loose all power. (normal this is after it has warmed up but
not
always almost always does it on a restart after a 10min drive) If I step
on
the clutch it will drop to a very muddy idle of about 400 then if I give
it
some gas but not full throttle the rpm decrease and will sometimes
stall.
If I give it full throttle sometimes it will clear it out. A restart
always
fixes the problem some times for the rest of the day sometimes for 1min.
If
I disconnect the O2 sensor (new splice in type spliced by my mechanic)
It
will won't normally lose all power but tends to surge while driving and
top
speed limited to about 40-50mph.
Now the reading of the Tool
TPS light is green at first start up will go green for full throttle
but
never goes back to green again for idle but always works on full
throttle.
I will adjust again to see if it helps. Next the O2 sensor readings the
02
sensor seems to be working fine according to your instruction book my
reads
are between .33 and .93 but the 02 ground is reading a -.4v
consistent.
Can I run the tool with the 02 unplugged to see if the ground still
read -.4v ? That way I can isolate it to the harness if it still read
-.4v
or the sensor if it reads the correct 0v. Would I be correct in assuming
that. Also I don't want to hurt the tool by running w/o the 02 sensor.
Any
suggestions you have on these issues would be great.
Thanks for your help,
Kevin
87 Westy
Burlington VT