I have a b5 S4 with the GIAC flash. The boost gauge i have reads in hkPa. When i got the flash done my boost levels went up to 1.2 and that was normal (about 16-18psi). So I was haveing fun for about two months with the flash and then one day it stopped making boost. Now its max in 3rd gear is about .6 hkPa.

My first thought was simple boost leak. So i brought the car to the shop and had the system tested, Found no leaks!! So now i am under the asumption that the GIAC has put the car into a safe mode for some reason. We pulled codes and found nothing.

So now i think the problim is from something michanical that does not have a sensor on it. I have tested the DV (baily motorsports) and they are fine, good suction and the piston stays up when i put my finger over the vacume hole. I dont think its the waist gates becaus that would cause the car to spike, right? So I am lost now.

If anyone has had this happen and knows or even has an ideo please help. I hope its not the turbos.