Originally posted by XtremeRS

Originally posted by BumpinTalon yeah that explanation makes sense, I understood that part totally. but should I have 43.5psi even at idle? I am not sure if I am stuck in the FMU school of thought, where they have really low idle pressures and insane boost pressures, or if I am just not understanding something really basic here.

Yeah, I usually tune fuel pressure to a fully warm idle. Even stock FPR that are vac referenced, will increase fuel rail pressure a little bit, as vac gets closer to 0(WOT for a non boosted engine). But since there is no positive pressure acting on the injectors, fuel pressure stays fairly consistant. The thing about FMU's and the like, is that when you want to run larger than stock injectors with a stock ECU, you have to lower the fuel pressure in order to get less fuel spray out of the injector, since the actual injector pulsewidth(injector "on" time) remains the same from the stock ECU.

Ahh alright thanks for clearing that up.