VW Jetta tdi- the turbo hasn't been working. Apparently, this vehicle is equipped with a ccv (crankcase vent) system and an egr (exhaust gas recirculation) system. Oily fumes from the ccv system combine with carbon particles from the egr system to form a black sticky tar in the intake system. This eventually starts restricting the amount of airflow into the engine, resulting in gradual power loss as the vehicle ages and the intake clogging becomes worse. This is apparently preventable by adjusting the intake air volume of 370 mg/stroke using a computer to reprogram the egr. Replacing the manifold & egr is an expensive proposition that is not covered under the powertrain warranty.

- Charlottesville, VA, USA