Engine Sputtering after 351W swap(EFI)

[jimberg]

Dark_5.0,

His computer should be able to compensate by reducing injector pulse length based on feedback from the O2 sensors. If he were to lower his fuel pressure, he'd get a bad spray pattern, like you said, which would cause inconsistent and incomplete combustion. That could lead to more problems in fuel management since it could cause false O2 sensor readings. As you probably already know, air/fuel ratio is controlled by the computer and not what the fuel pressure is set at. If his MAF sensor is calibrated to match his 30# injectors, he should be okay. 48psi is too high which is why I brought up how much HP my engine puts out. If I can get 345rwhp with 39psi, he clearly should be able to support whatever he's getting at 39psi. Maybe he can even drop it to 30psi to see if things improve, but I wouldn't go any lower than that.

Bluethunder87, when you drop your fuel pressure to 39 or even 30 psi, be sure to reset your computer and then let your car idle for about 10-15 minutes so it can relearn it's idle.

You should really upgrade to a 155 or 190lph fuel pump depending on what your plans are. It seems that the 155 is good for at least 345 rwhp.