Im looking to buy a 95 A6 quattro from a buddy. We are both techs and he got the car from a customer. It currently has a 97 2.8 in it which is obd2 but the car is a 95 obd1... Has the CEL on but I cant communicate with the engine controller only the trans. The engine is making a noise ive never heard before and throttle response sucks, thinking the cats are clogged but maybe the newer motor has something to do with it? im kinda lost, I have not tore into it at all yet. He says all compression is even and in spec, it acts like its a few teeth off on timing.

 

Audi 2x2 to OBD2 Adapter
Maybe it can help you .
But I am not sure ,