Bad lambda unit???

[fireant911]

How does one determine if the lambda unit is wasted? I have been attempting to record the voltage readings from the Oxygen Sensor and have found that when measuring the voltage from the Oxygen Sensor connected I get a reading of about 0.011 volts maximum. When I disconnect the sensor and measure directly from the sensor I record a value of between 0.750 and 0.950+ volts. The car is running very rich (based on the 'gassy' smell from the exhaust) and has terrible fuel mileage (17 mpg - highway). I disconnected the computer lead underneath the passenger seat and could detect and audible difference in the way the car was running - upon reconnecting this lead the engine goes back to normal. There is absolutely no difference in the running of the car whether or not the Oxygen Sensor is connected or disconnected - I have purchased two new Oxygen Sensors so that should not be the problem. My mechanic has recently adjusted the fuel pressure so it should be in proper specification. Bill Verburg, Lorenfb, and the other lambda experts, is my lambda unit shot?

Are there any additional tests that I can perform to conclude that the lambda unit is not operating properly? If the unit is indeed shot where does one find a used, functioning, reasonably priced replacement unit?

[Steve W]

You can't read the O2 sensor output properly while it is connected to the Lambda unit. Doing disconnected as you did the second way, is the only way to read it. As you found, the voltage is indicating a very rich mixture, so I would first try to adjust the mixture by leaning it out at the mixture screw in the flow sensor. Turning it counterclockwise reduces the amount the flow sensor plate lifts, thus reducing the amount of injected fuel.