LPFP Psi Too low?

[Bimmerny]

running Mhd v9 stage 2+, i believe i may have a hardware issue but wanted to confirm with you guys.

My current low pressure fuel pump psi is ranging between 66psi-68 psi at idle.

Recent maintenance includes an arc terminator ekp3, Lpfp fuel pressure sensor & VDO fuel filter/ fuel pressure regulator Unit.

Currently running a single Walboro 450 with approx 30k miles on it, prior to changing the
fuel filter/ fuel pressure regulator Unit idle lpfp psi was at 78 psi.

If i am not mistaken Target idle lpfp psi should be 72 Psi, would appreciate any insight

 

[Bimmerny]

Bump, could use some help

 

[eastsidaz]

Bump, could use some help

It's fine. It's more important at WOT got any logs?

 

[Bimmerny]

It's fine. It's more important at WOT got any logs?

Log 1: https://datazap.me/u/kush/log-1745590384?log=0&data=3-12-24-25&solo=3-24&zoom=0-92&mark=66

Log 2: https://datazap.me/u/kush/log-1745590369?log=0&data=3-25

Log 3: https://datazap.me/u/kush/log-1745590384?log=0&data=3-12-24-25

 

[ktb_e92]

Weird how it's doing that at idle, when before some of those part changes mentioned, you were seeing higher pressure. 70ish-80ish psi is what most peoples' LPFP psi sit at during idle. Otherwise, under boost yours seems to be fine. I saw occasional spikes down into the 50's, but if it were really an issue you'd see a negative trend tanking towards the 50's and 40's rather than a fairly consistent oscillation like how it does right now, which is how all of our cars basically are. For good measure, you could give it a shot at resetting the Lambda Sensors + Regulation adaptations along with Octane Rating. Aside from that, I wouldn't worry. Fueling parameters are hit & miss with OTS maps in terms of how spot-on they are. When you start adding more power / go with a custom tune and see it starting to drop more, then I would revisit troubleshooting what it could be.

 

[Bimmerny]

Weird how it's doing that at idle, when before some of those part changes mentioned, you were seeing higher pressure. 70ish-80ish psi is what most peoples' LPFP psi sit at during idle. Otherwise, under boost yours seems to be fine. I saw occasional spikes down into the 50's, but if it were really an issue you'd see a negative trend tanking towards the 50's and 40's rather than a fairly consistent oscillation like how it does right now, which is how all of our cars basically are. For good measure, you could give it a shot at resetting the Lambda Sensors + Regulation adaptations along with Octane Rating. Aside from that, I wouldn't worry. Fueling parameters are hit & miss with OTS maps in terms of how spot-on they are. When you start adding more power / go with a custom tune and see it starting to drop more, then I would revisit troubleshooting what it could be.

What started all of this is that i was out one day driving and when attempting to get into boost the car felt Naturally aspirated. I go on mhd monitoring and see lpfp psi is maxing at 85 psi steady. Thats when i upgraded the Ekp to the arc terminator and did the LPFP fuel pressure sensor. Then i was seeing 78psi for idle lpfp which i felt was too high.

Bought the VDO fuel filter unit from fcp euro, first one was defective and couldn't build more than 2 psi. Second unit i installed worked but was first at 70.9 psi, then next few start ups went to 68 psi and then 66psi and even saw 64 psi at idle which is throwing me off. Part of me thinks the VDO fuel filter is still is causing an issue unless the low pressure pump itself might be tired.

Check out my older logs from a few years ago and you see much more consistent lpfp psi.

Old log 1: https://datazap.me/u/kush/log-1612664088?log=0&data=3-11-19-20&solo=11-19&mark=30-65-82-32

Old log 2: https://datazap.me/u/kush/log-1612663987?log=0&data=3-11-20&solo=3-11&mark=123

 

[BoostedBafoon]

Can you check voltage output from your ekp? Just to be sure. Do you know if the arc terminator is pwm or not?

 

[oVeRdOsE]

I kept the venturi valve with the walbro 450, and I did some test.

- pump directly connected to the line with blackmarket 90° fitting = 72psi on idle.
- pump with the venturi = 69-70psi on idle. And yes randomly one day I saw a 68psi.
(ekpm3 with active cooling)

seems either the venturi leaking a bit by design, or my hose to the venturi is leaking. Wont be surprised if my hose is the issue, it poped out 3 times. On the last time Ive added many tywrap, fck that need to hold.

My logs looks good tho, pushing 26psi on a 6262 turbo.

 

[Bimmerny]

Can you check voltage output from your ekp? Just to be sure. Do you know if the arc terminator is pwm or not?

I didn’t check it but i did check that the fan on the ekp was working fine, i don’t think its the ekp as prior to changing the fuel filter unit it was at 78psi. Also i believe it’s not Pwm

 

[Bimmerny]

I kept the venturi valve with the walbro 450, and I did some test.

- pump directly connected to the line with blackmarket 90° fitting = 72psi on idle.
- pump with the venturi = 69-70psi on idle. And yes randomly one day I saw a 68psi.
(ekpm3 with active cooling)

seems either the venturi leaking a bit by design, or my hose to the venturi is leaking. Wont be surprised if my hose is the issue, it poped out 3 times. On the last time Ive added many tywrap, fck that need to hold.

My logs looks good tho, pushing 26psi on a 6262 turbo.

Would you mind posting pics or Pm me a pic of how it looks with it plugged in directly

 

[Bimmerny]

The odd thing is that with the defective Fuel filter Unit i installed. i heard a pop noise come from the fuel filter side when i tried to start the car for the first time and could never figure out what it was

 

[BoostedBafoon]

Probably the diaphragm or whatever they use internally to regulate pressure in that thing. I have yet to cut one apart to see but, if its anything like a standard static regulator. Its a good chance it may have failed again. Poor manufacturing or maybe your pump is over powering it. I know that the 274 walbros have an internal bypass thats over 100 psi or something. It could be too much volume and pressure at full blast on initial start up? My EKP is the same way, just turns my fuel pump on full speed all the time. But I have a completely different fuel system to handle it so to speak.

 

[Bimmerny]

Probably the diaphragm or whatever they use internally to regulate pressure in that thing. I have yet to cut one apart to see but, if its anything like a standard static regulator. Its a good chance it may have failed again. Poor manufacturing or maybe your pump is over powering it. I know that the 274 walbros have an internal bypass thats over 100 psi or something. It could be too much volume and pressure at full blast on initial start up? My EKP is the same way, just turns my fuel pump on full speed all the time. But I have a completely different fuel system to handle it so to speak.

Just curious could you check what your lpfp psi is at while idling?

 

[BoostedBafoon]

Mine starts out at like 73 psi and after it's all warmed up sits around 72. But I have an external regulator so I dont think that helps you much.

 

[Bimmerny]

Mine starts out at like 73 psi and after it's all warmed up sits around 72. But I have an external regulator so I dont think that helps you much.

That sounds like where it should be at, did you set a target psi?

 

[BoostedBafoon]

Yes, I set my external at 73. But I should reiterate that is not a target set in the DME. For me it is a physical adjustment, ie I have to turn a screw to adjust my fuel pressure now. Your new EKP setup will not follow any fuel pressure targets set in the DME either if it is relay based. It will just turn on and run at full voltage.

 

[Bimmerny]

Yes, I set my external at 73. But I should reiterate that is not a target set in the DME. For me it is a physical adjustment, ie I have to turn a screw to adjust my fuel pressure now. Your new EKP setup will not follow any fuel pressure targets set in the DME either if it is relay based. It will just turn on and run at full voltage.

Makes sense, What made you switch to external regulator?

 

[BoostedBafoon]

Makes sense, What made you switch to external regulator?

Much better control and fuel volume. But I have dual pumps and dual 3/8 feed lines and a hole mess of other nonsense no one needs. But I have odd ideas about the way things should be done.

 

[BoostedBafoon]

But to the point, it's not really an issue for you as maddening as that may sound. Your idle is ok and WOT is ok. I wonder if you have the original filter you replaced and tried putting that back in what you would get.

 

[Bimmerny]

Yes, I set my external at 73. But I should reiterate that is not a target set in the DME. For me it is a physical adjustment, ie I have to turn a screw to adjust my fuel pressure now. Your new EKP setup will not follow any fuel pressure targets set in the DME either if it is relay based. It will just turn on and run at full voltage.

I knew what you meant sounds like a very clean setup, i think i have some other issue going on