Hi all, first post. My s5 turbo II is acting very weird. It'll start up fine, but when it gets to about 1500rpm, it will just die, as if you turned the key off, no sputter or anything. However, when I unpligged the AFM, the car ran much smoother, for about 20seconds, then it died. The car was running perfectly fine just a few days earlier, but then I was going to do the fuel pump rewire, so I bypassed the fuel pump resistor relay, by soldering the power wires together and taping off the other two wires, as described in "option 1" in this video

You Tube

. When I plugged the connector back in, I had this problem, so I soledered the relay back in. But the exact same problem occured. I've tried everything, I can't find any vacuum leaks, and we even ran a power wire directly to the fuel pump but it made no difference. Car is completely stock with 40k miles on it. Does anyone know where to start looking for the problem?

 

With the AFM plugged in, start the engine and try to keep it running by pressing in the AFM plunger. If it stays running you probably have a vacuum leak.

 

I would undo whatever you did to the fuel pump wiring 😆. Or at least work backwards if it used to run fine (which it did from mazda). If it's completely stock you don't need to do things like this, it just is treating the symptom not the cause