problems accelerating...

[b5boy]

i just bought a 97 a4 1.8t not really sure what is done to it, other than a full exhaust and CAI. anyway it runs great in first gear boosts good but when i go into second and reach full boost the wideband drops to 10.00 which is really rich?? i believe. does anyone have an answer or idea to what could be causing this? i am thinking maybe a boost leak? or it needs a tune. it will kind of sputter when i really get on it in second, but fight through the sputter and pull out of it? any ideas or thoughts are welcome [:)]

[Seerlah]

Boost leak makes you run lean, not rich. What is your A/F ratio at idle?

Step 1: Find out what mods were done to your vehicle (detailed specs)

[b5boy]

its all over the place anywhere from 10.6-14.2 it will just bounce back and forth between that when driving normaly it hangs around 13.0-14.2 but when you get on it and it reaches full boost it drops to 10 flat... i tightened all the boost and vacuum lines last night and seems to be running a little better but still has the same problem. im having a guy that tunes them look at it on monday so hopefully he can point me in the right direction! thanks for the help though!

[CoreyRS]

did you ever resolve this?

My car was behaving similarly and I am pretty sure it was a failing diverter valve (Forge Splitter in my case). I took it out, disassembled, degreased the piss out of it, and my car runs much smoother.

If you have a stock diverter valve, listen for fluttering to determine if it is broken.