Lpfp psi drops under wot

JayN54Sosa

Lurker
Aug 16, 2022
12
0
0
Forest city, NC
Ride
E92 335i FBO+e85
My lpfp psi drops from the high 60s to the low 30s under WOT. I’ve went through 2 offbrand OEM pumps and now on a OEM VDO brand pump. My first old one was terrible and I admit it’s fixed a lot of the issue with new ones. However I still sometimes can get a solid pull in but mostly it’ll dips super low and my car goes in limp mode.

New HPFP, new LPFP, spark plugs, coilpacks, injectors seem to be fine, lpfp sensor is fairly new.

car is 2007 335i e92,msd81 upgrade DME, vrsf intercooler, catless downpipes, dualcones, chargepipe and blowoff valve, mhd stage2+.

I just recently am running e30 mix and it does pretty good with it and I’ve done some successful pulls but it’s almost the same as if it’s pump 93, still dips low sometimes and goes right back to normal after my pedal input is like 10-25%
 

GreyNBlueE92

Sergeant
Oct 3, 2018
263
91
0
26
OH
Ride
2007 E92 335i
Fit a walbro in there and you should be good. Factory pumps can barely keep up with E mixes unless your boost is kept low
 
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digitalashley

Specialist
Apr 8, 2019
65
21
0
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135i n54, E87 N54
Not sure what pump you have is rated to do flow wise but if it's not enough like a walbro 450 for example maybe try one of those and. If your not using factory stuff to connect the pump up leaks in lines will cause psi drops. Also which ekp module do you have 2 or 3 that's another thing to keep in mind if your pump has high current draw it may be causing issue with heat at the ekp module. I doubt this is a current issue with your setup but something to keep in mind if you upgrade, as they can get very warm as you may see online
 

JayN54Sosa

Lurker
Aug 16, 2022
12
0
0
Forest city, NC
Ride
E92 335i FBO+e85
Yeah, log will help. Also where were these pumps purchased from. If you say Amazon or Ebay you can be sure they are counterfeit.
I’m running a OEM VDO one off fcpeuro, which couldn’t keep up with 93 octane OR e30. My other 335i is perfectly fine but this one has been a non stop battle for me
 

Torgus

Colonel
Nov 6, 2016
2,415
1,929
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Boston
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ACF 6466 E92 + METH
Fit a walbro in there and you should be good. Factory pumps can barely keep up with E mixes unless your boost is kept low
This.

OP, I am surprised you spent the time to put in a new factory pump. Throw in a walbro. The factory pump does 'ok' but nothing impressive. You can easily run out of pump on factory turbos.
 
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digitalashley

Specialist
Apr 8, 2019
65
21
0
Ride
135i n54, E87 N54
I don't know jack. But I had fueling pressure issue on ijeos car and this is definitely much more drastic. I would suggest after looking at that log you need to swap your ekp with the other car you have and see what happens just plug it in and Then log. If it's the same I'd say it's your regulator or lpfp sensor or a decent leak inside the tank. But I doubt that as it's stock the pump doesn't sound weird right? And it was an pressure issue is why you replaced it?Ekp seems more likely as it's just 30psi the whole time you have throttle down. But I'd swap the ekp over first to test then check for leaks if that didn't help . And hopefully someone else chimes in with some good info as well. But yeah definitely be careful. Any errors?
 
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ShocknAwe

Captain
Jan 24, 2018
1,309
624
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Charleston, SC
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N54/3 1er ///Mutt
Either EKP or the actual LP sensor/line.

It's not completely flat like I first thought now that I see the chart on a screen, but damn close you only have like 2psi variance and it's at 30psi which is 20-30psi past failure.
 

JayN54Sosa

Lurker
Aug 16, 2022
12
0
0
Forest city, NC
Ride
E92 335i FBO+e85
Either EKP or the actual LP sensor/line.

It's not completely flat like I first thought now that I see the chart on a screen, but damn close you only have like 2psi variance and it's at 30psi which is 20-30psi past failure.
I never can find the actual part numbers for the lp lines
 

JayN54Sosa

Lurker
Aug 16, 2022
12
0
0
Forest city, NC
Ride
E92 335i FBO+e85
Either EKP or the actual LP sensor/line.

It's not completely flat like I first thought now that I see the chart on a screen, but damn close you only have like 2psi variance and it's at 30psi which is 20-30psi past failure.


New log with another EKPM3 off a different car and I also coded it.I also made a new post updating everything if you feel like checking it out.
 

ShocknAwe

Captain
Jan 24, 2018
1,309
624
0
Charleston, SC
Ride
N54/3 1er ///Mutt
A lot better. Still not good.

Have you checked your bucket to make sure the return lines are properly sitting inside? Or not kinked.
 

NoGuru

Captain
Jan 9, 2018
1,202
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Just North of Detroit
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BMW 335is
Yeah, still terrible, I would not rev out that car until you fix it. I agree with ShocknAwe, look for a kink or hole in the line inside the tank.