[JPuehl]

I have an early '12 135i with N55, FBO and PS2 and the HPFP has been having an issue keeping up >6k rpm and am wondering whether I need to upgrade the HPFP or LPFP. I run 19 psi tapering to 18.5 >=6k rpm but sometimes I have misfires because it gets lean because the HPFP can't keep up. I don't plan to run E85 enough to justify the cost of an upgraded HPFP. I know I have options that don't require upgrading anything; 1. shift @ 6k, 2. lower boost even more >6k, 3. lean >6k a bit. I'm wondering if an upgraded LPFP will help, but if not I'll upgrade the HPFP, I just don't want to upgrade the HPFP thinking I'll run E85 (because it's not convenient so I won't).

I have read that upgraded LPFPs will supply more fuel but if the HPFP "can't use it" then it won't make a difference.

[Schmidty335i]

I am in the same boat as you. I have a PS2 and above 6k i get misfire codes on only above 16psi. i upgraded my LPFP to a stage 2 no difference. I bought a Spool Performance FX-150 and just got it in this week. I plan on installing it this weekend. hopefully that fixes my issue.

[JPuehl]

Originally Posted by Schmidty335i

I am in the same boat as you. I have a PS2 and above 6k i get misfire codes on only above 16psi. i upgraded my LPFP to a stage 2 no difference. I bought a Spool Performance FX-150 and just got it in this week. I plan on installing it this weekend. hopefully that fixes my issue.

Interesting, your setup sounds very similar to mine PS2, FBO, JB4 + BEF. I'm interested in hearing about your results of the FX-150. Since it's a HPFP I would hope it resolves your issue. I've heard the XDI works well and is a bit cheaper, either way if an upgraded LPFP didn't help you a HPFP upgrade may be needed.

[Spooly]

Originally Posted by JPuehl

Interesting, your setup sounds very similar to mine PS2, FBO, JB4 + BEF. I'm interested in hearing about your results of the FX-150. Since it's a HPFP I would hope it resolves your issue. I've heard the XDI works well and is a bit cheaper, either way if an upgraded LPFP didn't help you a HPFP upgrade may be needed.

Any reason you are choosing not to run meth? You won't need too much more to add meth to your current system since you already have the JB4. You can simply run meth when you need it, and otherwise run a slightly less aggressive tune. I think that would easily take care of your fueling issue. Port injection is another option.

[CoffeeBean]

Yeah with the F30 style HPFP your only option other than port injection is to upgrade it. Better LPFP won't make any difference if the HPFP is maxed out. With port injection you can bypass the HPFP because it runs only off the LPFP.

[Schmidty335i]

Originally Posted by JPuehl

Interesting, your setup sounds very similar to mine PS2, FBO, JB4 + BEF. I'm interested in hearing about your results of the FX-150. Since it's a HPFP I would hope it resolves your issue. I've heard the XDI works well and is a bit cheaper, either way if an upgraded LPFP didn't help you a HPFP upgrade may be needed.

Update: Got my Spool HPFP installed yesterday and it works great! got rid of my misfires that have been plaguing me for months. Yes, i have pretty much the same setup as you PS2, FBO with a BEF. i think the xdi might be more expensive but i havent checked in a a bit. you have 3 options you can look at Spool performance, XDI and Dorch.

[Turbod]

I've seen a bunch of misinformation in different places about the need of a LPFP upgrade before a HPFP upgrade. If you replace the HPFP and you're planning to turn it up at all then I would look into a LPFP upgrade since there is no sensor to monitor how it is doing. No need for the LPFP until after a HPFP though.

I'm also an advocate for methanol injection and the JB4 makes it a simple add-on.

[ferocity02]

The Dorch HPFP is a better option than Spool, better engineered kit at less cost. I have FX-150 but wish I waited for the kit from Dorch.

[Schmidty335i]

Originally Posted by ferocity02

The Dorch HPFP is a better option than Spool, better engineered kit at less cost. I have FX-150 but wish I waited for the kit from Dorch.

what do you not like about the FX-150? it has a lifetime warranty and i got mine for a steal with their group buy. they included the HPFP, ethanol sensor and filter too. Couldn't be happier with the results. but honestly if they last i dont see why any one would be much better than the others. whatever one a person can get the best deal on at the moment is what i would suggest. Or wait a few years and see if any of the options out right now start failing.