Like 5-10 MPG literally :(

My car is BPU with the stock fuel pump hotwired. (3 inch turbo back no mufflers/cats, intake, MBC, FULL vac reduction)

After hot wiring my fuel pump and deleting the fuel pump relay and the fuel pump resistor (http://www.stealth316.com/2-fuelpumprelaybypass.htm) because my car was running lean I seriously have the worst MPG ever. It's really hurting my wallet BAD. What could be the issue? Running too rich?

I have the chance to buy an AFC for a good price if that would help at all. I am going to log my car tonight in hopes that someone can tell me what's wrong.

A bad rear turbo wouldn't do this would it? Mine burns oil and is dying.

Any ideas? Thanks <3

sounds like your over running the stock fuel pressure regulator. Fuel trims are probably pegged rich and still not enough to compensate. Your still on stock turbos. I would just keep the wiring stock and maybe upgrade to a walbro. Or get a better FPR

Log it and post your logs. Sounds like either a bad O2 causing it to run super rich, or the FPR over-running. The FPRs are like any other part of the car and can cause issues.

Thanks!

Would lowering boost help?

unlikely... your not using the fuel your injectors are providing anyway, so lowering the boost would theoretically make it worse

Check that fpr. If that's the case, it shouldn't be an expensive fix and is a simple swap :)

how can i check it?

plumb in a fuel pressure gauge. I'd worry more about what your trims and O2s are doing to see if it's a dead O2 sensor, or if there's another underlying issue.

A faulty AFM could also cause this couldn't it?

Do you have a logger? That would point to the issue real quick.

I don't see how it would be possible to be running lean, then hotwire the pump and see 5-10mpg due to overrunning the FPR. I hotwired my pump and saw a pressure increase, but I barely saw a change in my MPG. Something else is going on here.

totally forgot to ask :/ If you saw it running lean beforehand what are your trim numbers now?

You know go fucking figure that my logger battery is completely fucking dead. >:( As soon as I pull it off of the charger it dies. Awesome!! I can almost physically see my gas gauge go down!