B58TU MHD Stage 1 fueling issues (Solved!)

DJCarbine

New Member
May 25, 2024
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**SOLVED**
Issue was In Tank fuel pump filter clogged


Having a bit of an issue that I'm struggling to diagnose....

This is on a 2020 X3M40i
On an OTS stage 1 MHD tune, my HPFP rail pressure begins to crash and limp mode is activated along with a drivetrain error code (11A605: Fuel delivery rate to low, full engine output cannot be guaranteed)

The tuner who I am sharing datalogs with says my gen 2 B58 should have more than enough fueling for that level of power, and suggested I look into the FPC module and low pressure fuel pump.


I checked the wiring and connectors at the LPFP and FPC and they were in great shape, no corrosion or signs of heat damage.
Car otherwise starts and drives fine, stock tune has no issues and no rail pressure crashing (holds 5K psi to redline)
Car has the TU hpfp stock as its a 2020 model

Please see below datalog of a rail crash in 3rd gear

I am ordering a FPC module as they are relatively cheap and need no coding on the G chassis.... anyone else have any ideas on what this could be or what I could look at while I wait for the part to arrive?
 
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SLOWESTN54

Captain
Feb 9, 2021
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B.C. Canada
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2007 E92 335i
Having a bit of an issue that I'm struggling to diagnose....

This is on a 2020 X3M40i
On an OTS stage 1 MHD tune, my HPFP rail pressure begins to crash and limp mode is activated along with a drivetrain error code (11A605: Fuel delivery rate to low, full engine output cannot be guaranteed)

The tuner who I am sharing datalogs with says my gen 2 B58 should have more than enough fueling for that level of power, and suggested I look into the FPC module and low pressure fuel pump.


I checked the wiring and connectors at the LPFP and FPC and they were in great shape, no corrosion or signs of heat damage.
Car otherwise starts and drives fine, stock tune has no issues and no rail pressure crashing (holds 5K psi to redline)
Car has the TU hpfp stock as its a 2020 model

Please see below datalog of a rail crash in 3rd gear

I am ordering a FPC module as they are relatively cheap and need no coding on the G chassis.... anyone else have any ideas on what this could be or what I could look at while I wait for the part to arrive?
I have the same car, but that to me just looks like a failing TU pump. I'm currently on a MHD Stage 2 E40 tune, and the moment i floor it my rail pressure shoots up to 5k and holds steady, unlike yours that slowly climbs.
 
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DJCarbine

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May 25, 2024
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I have the same car, but that to me just looks like a failing TU pump. I'm currently on a MHD Stage 2 E40 tune, and the moment i floor it my rail pressure shoots up to 5k and holds steady, unlike yours that slowly climbs.
I should have the FPC and a new LPFP in the mail soon, I've begun sourcing a TU pump as well due to your comment. FPC and LPFP is pretty quick and easy, if that doesn't fix it then I will steal the HPFP from my wifes car (also a TU pump) and swap with mine to see if the issue resolves and post an update

Interesting note about my rail pressure not rising as quickly as yours, I should compare this recent datalog to my previous datalogs a month or so back and see if its a new thing or has always been that way


Thanks!
 

SLOWESTN54

Captain
Feb 9, 2021
1,258
986
0
24
B.C. Canada
Ride
2007 E92 335i
I should have the FPC and a new LPFP in the mail soon, I've begun sourcing a TU pump as well due to your comment. FPC and LPFP is pretty quick and easy, if that doesn't fix it then I will steal the HPFP from my wifes car (also a TU pump) and swap with mine to see if the issue resolves and post an update

Interesting note about my rail pressure not rising as quickly as yours, I should compare this recent datalog to my previous datalogs a month or so back and see if its a new thing or has always been that way


Thanks!
No worries, my thought process was based of I've yet to see many LPFP's fail. I've seen people max out the stock pump, but with your power level you shouldn't even be close. And watching that HPFP line slowly rise makes me think its the tu pump failing.
 
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DJCarbine

New Member
May 25, 2024
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So the FPC didnt solve the issue, but during in take fuel pump replacement I found all this green powder in the fuel bowl and clogging the filter.
Fairly confident this is the issue, going to run some datalogs in the next day or so and confirm. I installed a newer model fuel pump and had to splice into the factory harness due to a wiring changeover on 04/2020. BMW sells a repair harness but it is over $200. I got a used fuel pump with 900 miles on it and the factory harness for 80 bucks on ebay.


20240602_131223.jpg
20240602_131519.jpg
20240602_132019.jpg
 
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DJCarbine

New Member
May 25, 2024
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Any idea what that green crud is? Are you the original owner?
I am the second owner, the vehicle was purchased about a year ago certified pre-owned and it was off lease. Wasn't modified at all, and had around 30K miles when I took ownership. I'm assuming the green crud is due to the car maybe sitting during the winter with E10 fuel and the ethanol doing bad things with moisture/corrosion.

Never had this issue before on any fuel injected cars, tuned or otherwise.

I am also happy to report that the drivetrain malfunction/misfires/drivetrain error is completely gone.




Final culprit was the in tank fuel pump trying to do lines of green coke apparently