been running the k&n filter with the stock airbox removed... the filter is connected directly to the maf sensor like i've seen some people do... after a couple of days of driving around and enjoying the sound, i got the P115C code back... after doing some more research on that one, i figured i would clean the maf... so i took the maf off and sprayed with maf cleaner... reinstalled it and took it for a drive and about 10 minutes later, it came back on... i've checked all the piping around the area and it seems fine. the turbo inlet pipe is connected securely... that code is hard to get rid of... i'm either thinking of adding a 90 degree angled pipe between the filter and maf to see if that will help... although i've read that some people have had success with fitting a filter directly onto the maf... or just going back to the stock airbox... any thoughts?
I'd go back to stock and clear the code, just to see if it comes back. If it doesn't, you'll know what the problem was. If the code comes back, the problem is elsewhere, but at least you'll know it wasn't the k&n setup.
i had a coolant leak problem which had to get fixed first... i took it to the dealership and they fixed it... it wasn't cheap... but whatever they did... also cleared the cel... i figured they would just clear it for me... but it would come back anyway since all they were doing was replacing the water pump and thermostat... but ever since then... no cel... nothing... car runs great... and i've made no additional changes to the intake so i'm happy