Please help. I have read all the posts I can find on these o2 sensors but can't seem to find my problem. The car starts and runs fine. As soon as it warms up, it begins to smoke black, and when holding a steady speed the motor really acts up. As if someone were tapping the gas pedal really fast. The engine pulls fine while accellerating and while slowing down, only when trying to maintain a steady speed. I went to the Audi dealer and they said the o2 sensor is bad and the computer is bad. I replaced the o2 sensor with a new one and tried a working computer form a good car. No change. We diagnosed the car again and again I was told the o2 sensor is not giving any readings. They suggested that perhaps the o2 sensor is not getting any power.

Does anyone know how to check for power and if there is no power coming, does anyone know werhe it should be coming from?

I am really up to my ears with this car and just want to be able to sell it. The rest of the car is top notch.

thanks in advance for your help!!