I did a s4 na (eu spec with distributer) to s4 turbo swap.

I got the car started and everyting seems to be working. However when i turn on the ignition I can hear a buzzing sound from behind the engine. Also when i put my finger on the fuel pressure regulator or the fuel return hose I can feel it vibrating. Is this normal ?

 

Going to need a lot more info than that. Is this buzzing like a warning buzzer? Or is it just a vibration sound? As for the pressure regulator/return line, that is what is supposed to happen when you have the engine running.

 

ignition on, but engine off? if the buzzing and vibrations perfectly coincide, then you're probably just hearing and feeling the fuel pump pumping.

what pump did you get for your swap?

 

The buzzing is most likely comming from the FRP (vibration). I can hear it with the ignition on and engine off.
I got a FD fuel pump.