Oh..I think I got this!..you removed your OMP to go Premix..Correct?..If you did this,and it is an S5 then it would Go into "limp mode" because Even though you Took off the OMP,It is Electrical..the OMP Needs to be there..the Best thing to do in this case is to Hook the OMP Back up to the Electrical Connections and TIE it to something away from the Engine.Just let it Dangle..it doesn't need to be On the engine,It just needs to be hooked up in the wiring aspect of it.,.Try that...The S4 OMP is Mechanical,so it isn't hooked into the Electrical system,and the S4 has no CEL,and won't go into Limp mode..it's just the S5 that will do this..anyhow..I hope I am Right!,and If so PM me..I like when I can Help out!..cheers,STYX>

that's what he has done already. It's not throwing a CEL, and the car corrects it's "burping"

Burping???? let me in on your lingo homie!!!

lol, whatever it's doing!

Check your fuel pump ground.

Where is the fuel pump ground located??