Mods
Curt Brown ported head (stock size valves)
Curt Brown 70mm Stock Ported Intake manifold
Precision 6266 JB Sa0 kit .82 vband T3
GSC S3 Cams /w Kiggly springs & retainers
Full blown 70mm throttle body
Spoolinup COP
BR Double Pumper
BR Race FMIC
Precision 1000cc Injectors
Standard Arp head studs
Tial Q BOV
Tial 44mm mvr wastegate

Just got tuned a week ago and car was fine. I noticed I started to get some knock an afr would go lean around 5500 rpms from 11.7 to 12.6 up top... So far I have swapped fuel pressure regulators, pulled the fuels pumps both are working and getting power. Checked the fuel filter, it's good. I even did a boost leak test no leaks... I completely stumped and it's frustrating...

 

Data log?

Im having the same problem now. Drove it for 6 weeks and no issues. Went to leave the store and it started leaning out to the 15s mid throttle crusing.

I logged it and didnt find anything. Im thinking its a dying fuel pump or I have a leak in a line internal in the tank.

 

I had the same issue and it turned out to be a bad WB O2 sensor. Log O2 volts and see if the decrease when your WB shows lean. What's base FP? Is your siphon drilled? What boost is being run?

 

Think is was wiring