It sounds like DigiTool time. The DigiTool allows you to look at the
readings of the sensors in real time, as the ECU thinks they are
reading. Testing the sensors themselves doesn't tell you what the ECU
sees. Where are you located?

Mark

David Clarkson wrote:
> I am still trying to track down the rich running condition on my 90
> Westfalia. I thought that the problem may have been related to the ground path
> and have cleaned up the two ground points under the coil and have moved
> another  ground connection from the coolant tower previously to a better contact
> point. I  also replaced a connection for the green wire that attaches to the
> positive side  of the coil. No change. I also put together the test wiring
> harness discussed in  a previous thread from the article on the Samba. No
> changes with the problem  with the harness in place. I also tried shutting off
> and then restarting the  engine with the engine running to test the o2
> sensor per Dennis' suggestion.  This did correct the problem for a few seconds. I
> then disconnected the o2  sensor and still had the problem so I think this
> rules out the sensor. I had  previously found the correct voltage coming off
> of the sensor (.1-.7 volts). The  temp II sensor has been replaced and I
> have checked the wires to the sensor. I  am going to check the throttle switch
> to see if any problems are evident here  tomorrow. I also am going to use
> probe pins to try and check for voltages at the  computer from the temp I,
> temp II and AFM. Any other suggestions from the list  to check on this
> problem? The problem was an intermittent rich running problem  and now seems to be
> almost constant. Thanks gurus.
>
> David Clarkson
> 90 Westy
>