My daughter has a1998 A4 with a 4 cyl turbo engine. I replaced the head (timing belt tensioner issue) a few months ago. The pistons looked good when I had it apart. Her car started using oil. The car also started running rough at idle, sometimes dieing out in stop and go traffic. I pulled the intake off the throttle body and it is slick with oil. Can the turbo be causing this? If so I will replace the turbo, but how do I clean the Mass Air Flow Sensor and where is it located (I am thinking this is the idle problem, may be coated with oil)? If anyone has any other ideas, please steer me in the right direction.

 

A blown oil seal on the turbo can cause the oil issue, it could also be just a bad pcv system. The maf is attached to the airbox. Just remove it and spray it down with some maf cleaner