What causes LPFP Stage 2 pressure to bounce around so much?

[Jeffman]

Did a log last night chasing down an ignition issue and noticed my LPFP pressure bouncing around (64-87 psi during WOT log - see Datazap chart).
I’m:
Fuel-It Stage 2 Walbro 450 in tank.
E13 Fuel (mostly 93 Oct Shell VPower + some left over ethanol)
67,900 miles original miles on the LP sensor
Stock EKPM3 module (I always get the 2AAF Fuel pump plausibility code when outside temps > ~50F)

What causes the pressure swings? Could it be the under-powered EKP module? Is it time to replace the LPFP sensor and/or the Walbro? Would installing the new TorqueByte EKP module smooth out the pressure delivery?
Thanks.

datazap.me | Jeffman | FF E13 1.2 15.999 PR 72F Flat switched 1 / 2 coil wires

datazap.me

 

[GreyNBlueE92]

Wondering this as well, I thought maybe the bigger pump could flow enough fuel at a lower pressure and the car is ok with it but not sure... I have 130k miles on my ekp2 and see pressure as low as 63-64 up to 75ish psi

 

[Milan]

Go to Evolution of Speed's page and look up their fuel pump module, explains it perfectly

 

[Jeffman]

Go to Evolution of Speed's page and look up their fuel pump module, explains it perfectly

I did. I believe it only explains fuel pressure oscillations in the context of having a Hobbs switch turning on and off. But I have no Hobbs switch. Hmmm...
The website says, “Other solutions that utilize a Hobbs switch to activate additional fuel pumps actually work against the DME closed loop pressure control system. When the Hobbs switch activates, the DME is faced with a step increase in line pressure that it reacts to by lowering the output duty of the pump still under its control. The end result of this approach are massive fuel pressure oscillations caused by the DME software frantically attempting to servo the low system fuel pressure towards the target pressure levels.”

BPM4 Low Pressure Fuel Pump Controller EKP replacement

TORQBFM SOFTWARE DOWNLOAD CLICK HERE As many of you may have heard, we have been working with Torqbyte on developing of a fully integrated PT-CAN -based LPFP control module for performance-minded owners that prefer doing things the right way rather than entrusting their car’s fueling to other...

www.eospeed.com

But you may be on the right track here.

Who here has installed the BPM4 module and has much smoother reported LPFP pressures as a result of the module with just a stage 2 Walbro?

Thanks.

 

[Milan]

I think it's always true once you go to a 450, that pump out flow the stock one by a ton

 

[Jeffman]

I think it's always true once you go to a 450, that pump out flow the stock one by a ton

Indeed. I’d love to see a LPFP log before and after installing a BPM4.

 

[Jeffman]

I think I answered my question. In the BPM4 thread

Ad: - BPM4 (LPFP) Fuel Pump Control Module Released

In for more feedback. Thinking about ditching all the extra BS and simpilizing my fuel system. What would you like to know ?

bmw.spoolstreet.com

@martymil posted a log after receiving his BPM4 for Christmas last year. His LPFP pressure was quite steady.

datazap.me | martymil | Log 1545891436

datazap.me

Since many of Marty’s Datazap files are public I took a quick look at what he posted just before Christmas 2018 when he didn’t have the BPM4 LPFP controller and see that his LPFP pressures were bouncing around quite a bit.

datazap.me | martymil | Log 1545378742

datazap.me

This is the data that I was looking for!

I’ll finally be ordering a BPM4.

 

[matreyia]

Did a log last night chasing down an ignition issue and noticed my LPFP pressure bouncing around (64-87 psi during WOT log - see Datazap chart).
I’m:
Fuel-It Stage 2 Walbro 450 in tank.
E13 Fuel (mostly 93 Oct Shell VPower + some left over ethanol)
67,900 miles original miles on the LP sensor
Stock EKPM3 module (I always get the 2AAF Fuel pump plausibility code when outside temps > ~50F)

What causes the pressure swings? Could it be the under-powered EKP module? Is it time to replace the LPFP sensor and/or the Walbro? Would installing the new TorqueByte EKP module would smooth out the pressure delivery?
Thanks.

datazap.me | Jeffman | FF E13 1.2 15.999 PR 72F Flat switched 1 / 2 coil wires

datazap.me

Same exact symptoms as me...then I replaced the contoller with torqbyte and not a single isse again. Rock steady.

 

[veer90]

stock EKP is trash.

either hardwire with relay and fpr/return with your pump of choice or pony up for EOS controller.

 

[martymil]

The torquebyte controller is awesome but If you have a stage 3 pump or better you are going to need a better connection to the 2nd pump as the two post bolt system tends to get hot and melt through the plastic hat

Eos has their billet hat which seems to be the only proper solution for now

 

[matreyia]

The torquebyte controller is awesome but If you have a stage 3 pump or better you are going to need a better connection to the 2nd pump as the two post bolt system tends to get hot and melt through the plastic hat

Eos has their billet hat which seems to be the only proper solution for now

Tried searching for the billet hat on their site... no luck.

 

[martymil]

Contact him.directly

 

[scrllock]

The torquebyte controller is awesome but If you have a stage 3 pump or better you are going to need a better connection to the 2nd pump as the two post bolt system tends to get hot and melt through the plastic hat

Eos has their billet hat which seems to be the only proper solution for now

Per EOS you can just use screws with less resistance: https://bmw.spoolstreet.com/threads...ontrol-module-released.4377/page-6#post-67342

 

[martymil]

I'll be testing an oem integrated way by using the tank level connector (exactly the same size pins) for the second pump and relocating the tank level wiring to another connector.

Picked up a second pump from the wreckers which gives me all the pieces I need for next to nothing but billet hat is the way to go and far superior.

 

[scrllock]

EOS also directed me to these, too:

Electrical Bulkhead Stud Kit, 6 Pack

Electrical conductive bulkhead studs

www.radiumauto.com

@martymil What was your experience with stage 3 on the bpm4? Did you use different screws or get their billet top hat already?

 

[martymil]

I had the post melt through my hat but I'm not doing the post crap on my car again, I'll wait till I can do it properly

 

[Jake@MHD]

It can be fixed with lpfp pid tuning but I haven't had time to dig all that up.