well I rebuilt my S4 N/A with a small street port and now it is running like crap! I got it to start,run, and idle. BUT when I step on the pedal it is real speratic, sputtering, backfiring(popping). I made sure that the mark on the main pulley was lined up and that the CAS was lined up properly. I don't have a timing light but have tried adjusting the CAS a little at a time and it hasn't helped. I have adjusted the screw on the top of the UIM... Any advice would be greatly appreciated.

 

AFM plugged in?

 

Yes it is

 

Have you checked the Injector wiring?..

 

"need help tuning" besides a streetport, what other mods have you done?

 

Yeah, makes sure the injectors aren't wired backwards. It will cause similar symptoms.

 

Im also having similar problems with my streetport. It feels like it wants to run fast but it seems to be bogged down. To me it almost seems like its not getting enough gas. Everything is still stock.. Do i need bigger injectors or a better fuel pump to get the full potential out of my streetport?

 

Stock fuel system will support 200hp, so no u don't need to up ur fuel system.

 

For the op, check ur injector plugs and spark plug wires.