There's already an existing article on adjusting camshaft torsion after doing a timing belt on a SOHC PD engine here http://www.myturbodiesel.com/1000q/multi/PD-adjust-Idle-TDI.htm but I added a video today:http://youtu.be/pAEmqvUpKEY Basically, this is an optional but suggested step after replacing the timing belt on any VW TDI or Audi TDI pumpe duse engine (PD). A SOHC engine is shown, I'm not sure what extra steps a DOHC would require. This could also fix a rough idle if the rough idle is caused by timing that is off or has retarded over the life of the timing belt. Another common cause of rough idle is a bad flywheel or bad camshaft. See the FAQ for more on these separate topics. This will not adjust idle rpm speed since that is computer controlled. This only adjusts the camshaft timing. PD engines not only have to open the valves but they also pressurize the fuel injectors. The solenoid (or piezoelement on newer Euro market engines) then releases the fuel.