im having an odd issue with my s4 t2, for some reason it bucks when i try to keep a constant speed like on the freeway or whatever, and the only time it stops is like when i give it gas and go into boost, and whenever i let off the gas it starts backfiring. it runs and drive perfect fine no loss of power once or ever, i just werid and i dont know what it could be. all my emissions have been deleted, and its never been a problem before, just kinda started doing it, any suggestions?

 

We had a surging problem in the 3-4k range with our S5 Tii. Turned out that the porting, Bonez cat and Corksport exhaust all conspired to make us run lean in that range even with the RTek1.8 and 720/1000 injectors. So maybe your mods and emissions removal are biting you.

Another thing to consider is that while cruising you should be in closed loop so maybe your O2 sensor is going bad.

 

Reset the throttle position sensor. Procedure is in the FSM as well as online. If that doesn't do it, check the o2 sensor as stated above.

 

id check the tps or look into a fuel problem maybe?

 

I had this issue before....after I replaced the TPS and ECU, it was gone. Most likely was the faulty TPS.

 

Had that issue on the fd. Went away after I got new fuel. Maybe bad gas?

 

I had to adust the tps on my car like 3 times before I got a similar problem to go away. Don't know if that helps, but if I were you I'd start there. I had no emissions though with a modded tb. That may have had something to do with it on mine.