As many European Petrol heads know, BMW has been building amazing diesel power plants since the early 1980's. Unfortunately for us in the USA, we didn't start seeing the popular models diesel equipped until the late 2000's. The Sedans and SUV's have been proven to get better mileage and performance then their comparably equipped Gasoline counterparts. Reliability and performance are easy to achieve if some simple maintenance and performance task are performed.
A common issues to be dealt with currently on the BMW diesels is Carbon build up. Due to the nature of the direct injected engine, its common for the intake manifold, swirl flap passages, EGR, and Throttle body to be "plugged" up with carbon. This can lead to poor performance, misfires, failure of hard parts, and limp mode. It is very common for vehicles to exhibit rough idle, check engine lights, poor fuel economy and limp mode. It is not uncommon for vehicles to be diagnosed as needing new fuel injectors, when in reality the carbon build up is causing misfires.
The solution for this carbon build up, is simple, remove the carbon build up. This is easier said then done. The only way to properly remove the carbon build up is to remove the intake manifold and other components and then walnut blast the cylinder head passages and ultra sonic clean the intake and other components. Walnut blasting on the BMW diesel engines usually needs to be performed every 60k to 80k miles depending on the vehicles driving habits.
Walnut blasting should always be performed by a trained technician, as improper use of tools or blasting media can lead to permanent engine damage, or hard to diagnose issues. Since walnut media is being directly blasted on to the intake passages, and intake valve face, it is easy to introduce media and foreign objects directly into the cylinders.
After media blasting and cleaning of the components the computer systems need to be reset, adapted, along with the computer increment wheel changed. This is a BMW procedure to ensure correct fuel adaptation after carbon cleaning. We also recommend a DPF cleaning at this same time, or at least a DPF Regeneration. We have a tool for performing on vehicle Diesel Particulate filter cleaning and regeneration.