Date: Thu, 24 Jul 2014 08:15:56 -0400
Reply-To: Larry Alofs <lalofs@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Larry Alofs <lalofs@GMAIL.COM>
Subject: Re: diagnostic help? running rich(?)...
In-Reply-To: <CAHTkEuLu2S3yr59X=bO95hc_fi-GsSXubkiCJpBK=pUv_bNMYg@mail.gmail.com>
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Yea...What Chris said.
Devise a way to connect the meter to the signal wire of the O2 sensor
while it is connected to the harness. Be sure you have a good ground
connection for the negative meter lead. When the engine is running and the
sensor and engine are warmed up the voltage should go back and forth from a
tenth of a volt or less to about nine tenths of a volt. The meter reading
may look rather erratic depending on how fast it updates. At idle the
voltage movement may be sluggish, but at 2K rpm or so it should go up and
down in a second or two.
If you have the sensor out, you can test it with an ordinary propane
torch. Move various parts of the flame over the sensor tip and get it
quite hot. You should be able to get 0.8 V or so and it should go back to
0 quickly when the flame is removed.
If youknow which terminal at the ECU receives the O2 signal, you should
check the continuity of that wire from the sensor and make sure that it is
not shorting to ground.
Good luck,
Larry A.
On Wed, Jul 23, 2014 at 6:39 PM, Don Hanson <dhanson928@gmail.com> wrote:
> Hi all, 84 vanagon, inline Jetta 1.8liter running on Digifant system,
> same as the older Vanagons.
>
> Ok so here's the symptoms and the pertinent back story, if someone could
> send me after the right fix I would certainly appreciate it..
>
> I recently replaced my 02 sensor and fixed a loose vacuum line and the
> engine has been running great...until just now. It began running very
> rough, but running smooth again for a few seconds after turning off the
> ignition and back on...So I 'nursed' it home and put it up, crawled under
> to check the O2 sensor...the last thing I fixed...Sure enough, that O2
> sensor plug (flat, four prong) was partly loose...re-plugged it and
> ......after a few seconds, it again began to run really rough again and it
> smells really rich. Turn it off and on....smooth for a few seconds and
> back to rough.... So, I unplug the O2 sensor plug, re start and it stays
> smooth....
> So me thinks I have a problem involving the O2 sensor (it was a new
> one, I installed it about 400 miles ago only) or one of the wires or
> something that gets a signal from the O2 sensor...What the heck should I
> began with here?...I did use some contact cleaner and make certain the plug
> connection is good.
> I am about to go out and open up my wires between the plug and the
> sensor to check and make sure those splices are good...Is there anything
> else that may be causing this? Oh, I also checked that the ground wire for
> the O2 sensor has a good connection. Yes it seems to.
>
> Help. I don't want to run with a disconnected 02 sensor because I
> have been getting such great gas mileage since I put the new one in....2+
> mpg better than before I replaced it. Oh yes....messing with the
> throttle switches and the connections on the Temp II sender, that makes no
> change in how it runs...
>
> Don Hanson
>
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