Good point, Mark, but measuring the voltage should give me an idea if
the ECU is being driven by a faulty O2 sensor.

Charles
'85 Westy

At 07:37 PM 8/30/2006, Mark Drillock wrote:
>While there may be good reasons for checking the effect of disconnecting
>the oxygen sensor, the fact that an engine runs better with it unplugged
>in no way proves that anything is wrong with it or it's wiring.
>
>The oxygen sensor provides an exhaust gas feedback signal to the ECU but
>it can only see the combined gases of all 4 cylinders put together. If
>one cylinder is putting out a much different oxygen level than the other
>3, this throws the combined reading off and the oxygen sensor signals
>this off reading to the ECU. The ECU may then attempt to correct this
>combined reading but can only do so by adjusting all 4 cylinders at
>once, even the 3 that were in fact working fine. This can result in an
>overall worse running engine than would be seen with a disconnected
>oxygen sensor in spite of the fact that the oxygen sensor was doing it's
>job properly.
>
>Mark
>
>
>Sam Walters wrote:
>
>>Charles,
>>
>>Attached are some files for assistance in diagnosis of fuel injection
>>system difficulties.
>>
>>Disconnect the O2 sensor and see if the problem goes away.  If so, it is
>>either the O2 sensor or its wiring.  You can run this way for a day or
>>two to compare.  Wiggling the wire is no test of the O2 sensor.
>>........................
>>