I have just installed a AFR gauge from autometer.. I had to lengthen the wires a bit but I soldered it.. and I took te ground, +12V from the ECU..
The problem is that the gauge shows lean most of the time.. except when 'm on very light throttle on slow speeds.. when I open up the throttle 3/4 it light up the left most lean LED.. at idle.. it so lean it is of the scale..
but.. I smell gasoline now and then en my car backfires a lot so I think my car is running very rich.. and that the lambda sensor is broken..

some more information about the car.. it idles good.. 1500rpm when cold.. and a steady 700rpm or so when warm.. performance is good.. boost is 0,5bar (just installed a boost gauge wohee.. ) at wot in third @ 4000rpm.. fuel consumption is.. well I don't think about it.. at 1,42 eur the liter..
so what could it be..

btw the car is a S5 1991 turboII.. eurospec

 

or should I say the oxygen sensor is broken?
I'm going to measure the voltage.. it should be between 0,5V and 1V right?