Fuel Pressure regulator

[Technick]

Just do not get carried away with to much fuel pressure, 32-35psi at an idle (stock cam) is normal, 40-44 psi at WOT (no vacume) is also normal. For drag racing you can get away with raising the pressure above that, say to 48-52 psi and maybe make a little more power, BUT, in daily street driving you will find that you will have some driveability issues with the pressure set that high. At WOT the ECU does not make any A/F raito changes, it goes to a predetermined "map" and stayes there. By going with more pressure you are enrichening the A/F ratio of the engine. Now at normal cruise and idle the ECU "looks" at the 02 sensors and "see's" the richer A/F ratio and trims back the pulse width of the injector to try and lean the engine out to "prefered" 14.7:1 A/F. So since the injector is "leaned" out and the pulse width is not what the ECU see's normally in that situation, it hunts back and forth trying to find a happy medium. Then you feel this driveability issue and think "man this thing needs MORE fuel" so you raise the pressure some more and the ECU leans it back out ect ect. can be a vicious cycle. So start on the conceritive side of the pressure issue. Especially with bigger injectors you may find that LESS pressure makes the car run better as the ECU does not have to trim the pulsewidth back so far. Remember less pressure equal MORE volume from the pump, More pressure equal LESS volume from the pump.