Re: O² Sensor Diagnostics

["David Teitelbaum" <jtrealty@xxxx>]

Read D:04:14 and 15 in the Workshop Manual. Then get an old analog
dwell meter (the kind with a needle that moves, not a digital) and
hook up to the diagnostic plug as per M:03:01 to pins 2 and 3. Now
compare the readings you get to the pulse ratios on D:04:15 5 A-E. If
your mixture screw is way out of adjustment they may be off. You
should at least see the readings fluctuate and they should be close
when cold or at full enrichment. If the readings never fluctuate then
the sensor may be bad. Before replacing the O2 sensor test out the
entire circuit as per D:04:12. A grounded LG circuit (pin 7) or a bad
switch could cause the Lambda to stay full on. If the car has over
30,000 miles the O2 sensor should be replaced after adjusting the
valves and resetting the Lambda counter.
David Teitelbaum
vin 10757


--- In dmcnews@xxxxxxxxxxxxxxx, "Harold McElraft" <hmcelraft@xxxx> wrote:
> Dave
> 
> When the oxygen sensor is disconnected it tells the lambda computer 
> to default to a fuel rich condition by sending a default frequency 
> to the frequency valve. The sensor senses oxygen, that's all. It 
> does not know rich or lean, etc. So, in order for the sensor to do 
> its job correctly, everything else has to be working properly. 
> Exhaust leaks can cause too much oxygen, misfires can cause too much 
> oxygen, and vacuum leaks can cause too much oxygen and so on.
>