I recently bought a 1998 A4 quattro 1.8t awd. Next day the engine light came on(steady not flashing) and I noticed the car shakes at idle(gentle shake not too rough). It drives really good and smooth- no abnormal sounds or anything like that. Fuel economy is about 10 to 11L/100km. I took it to Mr. Lube for a free ECM scan. The codes were: P0134( o2 sensor) and P0304(cylinder 4 misfire). So I'm guessing it is the misfiring that is causing the shaking. Since the car runs very good and has a nice pick-up, I'm ruling out any compression problems - although it could be anything. Any one has any idea what else could it be causing the misfiring?. Could faulty MAF meter cause misfiring? or a bad o2 sensor can cause misfiring?

Oh.. and how can I tell if my car is chipped or not

Any feed back muchly appreciated

 

From my experience it's the coils.
I replaced all of them myself, OEM parts available @ audi ($180/4).

Easy to install!

 

Replace all 4 coils.

O2 sensor code was triggered because car's running rich if the engine is misfiring.