Fuel Pressure Regulator Questions

[Robo's]

Just got a Nismo Fuel Pressure Regulator and i know most are going to say take it to a dyno, which i am, but i want to know before i get there.

1) To increase flow, i turn the screw out just like a bleed valve.

2) When i increase flow, my A/F will be filthy rich as i won't be changing the values on my PFC.

[blind_elk]

FPR has nothing to do with flow - it simply controls the pressure in the fuel lines.

So:

1) to increase pressure, RTFM

2) when you increase pressure, yes, your A/F will be richer than it is now.

[Robo's]

Anyone else

[Busky2k]

I wouldnt blindly start changing the fuel pressure without a gauge. But yeah everything will become richer as pressure goes up, but if you have O2 sensor compensation turned on, light load operation shouldnt be affected.

[djr81]

Anyone else

<{POST_SNAPBACK}>

How bout if I have a go. There are two interelated parameters: Flow (ie the amount of fuel flowing through the injector rail) & pressure (ie as seen by the injectors). If you increase the rail pressure the pump output will drop, ie the higher pressure the pump has to work against the lower its flow rate Pretty straight forward really.

However, the opposite happens to the injectors, ie the higher the pressure in the fuel rail the more fuel the fuel injectors will flow. Hence, the higher pressure you dial into the regulator, the richer your motor will run.

[Robo's]

So if i see 98% injector cycle now, even if i turn up the pressure i will still see 98% injector cycle but the motor will be running richer than before

[DRFTR33]

So if i see 98% injector cycle now, even if i turn up the pressure i will still see 98% injector cycle but the motor will be running richer than before

<{POST_SNAPBACK}>

thats right.with the increase in fuel pressure your injectors will just spray more fuel during the time that they are open for, making it run richer at the same injector duty cycle

you have the right idea. if you had after market management and you increase the fuel pressure you can lower your duty cycle

thats what i have done with mine