I have a 2000 Audi a4 b5 1.8t. so I've been having a problem well under boosted I hit around 18-20lbs and it makes a loud pop sound, and won't accelerate and surges and then accelerates when the Boost drops down to like 15. I just replace the spark plugs so that can't be the issue. Also I was running a mode shake machine ran fine then I installed a test pipe and after that when the car started to act up. So the mode shake broke so have friend rebuiling it soon. So I am running the n75. Little extra I bought the car from a guy who own the car senses 2004 he did put a gaic tun on it which I don't have the files for, I'm thinking the tun might be out of wack too. Any feedback​ would help.

 

hi, friend
i have the same problem with you,if you have the solution please tell me.
best wishes to you.

 

I'm still not sure what's it up. I'm thinking it might be my o2 sensers might be bad. Cuz I did switch out my coil packs and still same issue. What's going on with yours