I have a few codes and a large problem. My 03 1.8t a4 was running fine, then a little while ago I had a quick misfire and an check engine light, which went away. Then it came back much worse. Now every time start to hit anything above 8 or 9 psi boost my engine starts misfiring like crazy. I am running apr 1+ software. Now here are the issues I havent put on an exhaust yet, which the tuner said would be ok. I am also using siemens 380cc injectors which eurocode said were compatible. My codes are...

18062.P1654 dtc memory of instrument cluster
17536.P1128 bank 1 mixture adaption - system too lean
17522.p1114 bank 1 sensor 2 internal resistance too large

These are besides the misfire codes. I already sent an email about the injectors. But do need a new MAF, a new rear o2 sensor, an exhaust or all of them??

 

I would clear the codes. Check your spark plugs, which ones are you running, gap them to specs? I'm running the same injectors and the only year that they aren't compatible is for the 02 model according to ECS, I don't know why though. I don't think you need a maf, but it wouldn't hurt to clean it. I had my O2 sensor give me a cel on my A6 but I never got around to it and the cel went away.