Fuel Pressure Regulator questions

[-bimmerboy-]

Okay so i was recently told at the local "e30 shop" here in Nashville that i needed to buy an adjustable fuel pressure regulator to take advantage of any modifications done to the car....is this true? Do i really need one of these things? All i have is the miller maf., miller chip, 19# injectors, long tube headers, 272 cam, hd valve springs, hd rockers, hi flow cat, single 3' piping from cat back to flowmaster, and a cone filter.

[SmokeE30]

Injectors flow differently at different fuel pressures so if your injectors are rated to be 19lbs at 3 bar and your running them at 2.5 bar they will flow less. With an adjustable FPR you could compensate for this but it really depends on what your setup is, I wouldn't call it a requiment just like standalone isn't required, but it is useful.

[Earendil]

Injectors flow differently at different fuel pressures so if your injectors are rated to be 19lbs at 3 bar and your running them at 2.5 bar they will flow less. With an adjustable FPR you could compensate for this but it really depends on what your setup is, I wouldn't call it a requiment just like standalone isn't required, but it is useful.

Right. It may or may not be required, as the ECU can compensate to some degree by leaving the injectors open for a different amount of time. However the assumption that the ECU makes is that the pressure is 2.5bars, so things like your economy gauge will not function properly. In other words, it depends on your definition of "required" :)

[jlevie]

19lb injectors are beyond what the stock DME can adjust for. To use those, even without other mods, you need a chip tuned for those. In this case with the other mods you need a chip tuned specifically for the that combination. Which probably means several hours of dyno time and a custom tune.

[-bimmerboy-]

19lb injectors are beyond what the stock DME can adjust for. To use those, even without other mods, you need a chip tuned for those. In this case with the other mods you need a chip tuned specifically for the that combination. Which probably means several hours of dyno time and a custom tune.

I have the miller 19# chip that is for the maf. Is that good enough?

[MR 325]

Yes that's good. Don't buy an adjustable FPR. You don't need it! Just make sure you have the correct 3 bar FPR from a M20B25 car.

[Alex Mc]

Yeah, 3.0bar is for 'i' engines.. 2.5bar is only for eta motors, which I don't think is what's being discussed here.