I bought an APR chip last week and threw it into my car. I had APR install it into a computer for me and then they sent it back to me. Needless to say I stuck it into the S4 and My car seems to run alot worse with it in it. Its a completely stock s4 and I start off fine in 1st gear but once it climbs to 3000 rpms it starts bucking and I cant seem to get past 3500 rpms in any gear because its bucking so much. on top of that the turbos sounds too much louder than normal. Any suggestions on the problem??

 

I had the same problem w/ mine, I thought it could be a leak or something, so I replaced all hoses w/ samco, and after a few days it drove great, and alot faster than stock

 

Did your regap your spark plugs? That would be the obvious problem You increased the power a good amount and should lower the gap ~.04 and also get a heat range colder plugs

 

I agree withboth above, especially check the y pipe, my friends s4 did same thing when it toreafter chipping. And plug gap would definitely do it too