MHD Issues

[Jkc19delta]

First Post!
Link to datazap (80% throttle towards the end of the log, beginning was backing out of the driveway and heading to end of the street)

FBO M-Sport 08 E90 N54 AT, VRSF 3” catless DP, VRSF Charge pipe w/ tial bov, VRSF street exhaust, BMS DCAI, BMS OCC, ARM 7” FMIC, VRSF silicone 3” inlets, one step colder NGK spark plugs gapped to .022, Eldor coils, and recent walnut blast (coils, plugs and walnut blast <200 miles). Recently changed boost solenoids and all vacuum lines at the same time as the walnut blast.

Initially, I flashed my car to MHD V10 Stage 2+ 93 Oct as that was the fuel I was running. The car ran fine on my way to work; however, after work (about 9 hours later), the car was struggling to accelerate. On a relatively straight backroad, I wanted to take a log to see what was going on; when I went WOT in 3rd, the car went into Limp Mode almost instantly, so I pulled off to the side to turn it off and back on. After turning it back on, the car idled for all of 30 seconds (generous length), and then RPMs fell to 0. I cleared codes with only ignition on and made it back home. Earlier today, I reflashed to Stage 2+ 91 Oct and reset adaptations. After doing so, the car ran fine for about a minute (very generous) and then went back to struggling (also a metallic sound coming from underneath the passenger seat area). I went to take a test drive, and the car was stuttering whenever I depressed the throttle; it’s very jerky, and it also seems like it’s struggling to make a boost.

I’m sorry about the poor quality of the log. I was honestly scared to go WOT. After flashing, I encountered these issues and read on various other forums and posts that I should reset all adaptations minus the battery. I did this, and the car improved for about 20 seconds, and then the rail pressure dropped significantly. At 80% throttle, my rail pressure was under 800psi, which, from reading other posts, is way under the 1500-2000psi target. The LPFP was sitting between 70-80psi, which I gathered is pretty standard. My main question is whether I should replace the sensor or the entire HPFP? Or do y'all think it could be something else entirely? Should I flash it to the stock map? I included my current codes and the codes that were present before reflashing and resetting adaptations.

Current Codes:
2AAF - DME: Fuel pump, plausibility;
2DED - DME: Power management, closed-circuit current violation

Codes before reflashing and resetting adaptations:
2FCA - Fuel high pressure bei Freigabe der Einspritzung;
2FDA - Fuel high pressure bei order nach Freigabe der Einspritzung (2. Umweltbedingungssatz nach Zeitverzoegerung);
2FDB - Fuel high pressure nach Freigabe der Einspritzung;
29E2 - DME: Fuel injector rail, pressure-sensor signal

 

[pbondar]

My guess it’s the HPFP…

 

[Jkc19delta]

My guess it’s the HPFP…

Thanks for the response, I thought so but just wanted another opinion before I buy a new one!

 

[JohnDaviz]

My guess it’s the HPFP…

Agreed

 

[ktb_e92]

In simple terms, 2FCA, 2FDA, and 2FDB translate to a fault in fuel high pressure during and/or after the release of injection. In short, 95% of the time it's due to the HPFP failing. Your rail pressure is pretty erratic and doesn't even see much more than 1,000psi, even when you got on it a little as mentioned. That seems too major to be an injector failure or else you'd see different codes and not run as poorly as you're describing. I'd start by replacing the HPFP. Get the $1,100 one, very hit & miss with the cheaper FCP re-manned and similar. I personally know multiple people who have gone through 2-5 of the cheaper re-manned options before sending it back for the actual BMW-sold one and never have issues after. FCP & ECS sell the BMW one with a lifetime warranty just like the cheaper re-mans.

As far as the 2DED code, I feel like that's a coincidence. That could be anything, mine usually trips that code after sitting for a few days but still starts right up and never returns once cleared. Keep us updated.

 

[Jkc19delta]

@ktb_e92 Sorry for the long time between the original post and this update. The part came in on Friday(29th). The old HPFP, inlet pipe, and spark plugs were replaced, and adaptations were reset via MHD on Saturday(30th).

At first, the fuel rail pressure was between 2400 and 2600 PSI, but it dropped to around 800 PSI after warming up. I depressed the accelerator and got RPMS up to around 2500-3000, and as soon as I took my foot off the gas, the car sputtered and struggled to stay running. I did this a second time, and the car cut off. I turned the car back on and tried again, and it struggled to stay on after pushing the gas; I did this a couple of more times, and the car didn't shut off but sputtered and struggled, so I just decided to stop.

I am not entirely sure what it could be now, but I am thinking, potentially, about the fuel pump control unit, the entire fuel pump module assembly, or just the fuel filter. Do y'all have any thoughts?

Thanks for all the insight given already, as well as any additional knowledge/advice!

The worst part about this is I work full time, I'm in college full time (commuter student... yay!), and this whole mess is just in time for finals week

Pic of my poor baby just b/c

Edit to add - still get the following codes:
2AAF - DME: Fuel pump, plausibility;
2FCA - Fuel high pressure bei Freigabe der Einspritzung;
2FDA - Fuel high pressure bei order nach Freigabe der Einspritzung (2. Umweltbedingungssatz nach Zeitverzoegerung);

2nd edit to add another thought: What about the high-pressure fuel pressure sensor that's on the fuel rail? Could that be the culprit?

 

[ktb_e92]

All good, glad it seemed that install went well aside from the price you have to pay for these HPFP's which is the worst part. What HPFP did you buy? There could be a chance that the rail pressure sensor needs replaced. If that's the case and your car acts fine after, it's up to you whether you want to get your $1000 back by either selling the pump on marketplace or returning it, if it falls within policy. I'd also make sure you keep an eye on the low pressure behavior because there could be a chance something on that end could be causing the issue too. If the readings are within reason (60-90psi) from the time you start the car till the time it starts to act up, that's how you can rule out the low pressure system.

Like you mentioned, the common causes of a failing LPFP include a code for plausibility, caused by the failing LPFP itself, fuel pressure regulator, or an old & clogged filter. An EKP module is also a possibility, but it's much more common to see that fail when someone starts to run an upgraded LPFP setup that happens to not be able to keep up with the added voltage demand. By that point, it may be worth buying a whole new LPFP assembly so you don't have to keep digging back into the tank for future failures after just finishing up one repair. It's up to you whether you want an upgraded one or not depending on your power goals. It's such a proactive move by going with a bucket-less setup due to the higher flow supply for any horsepower up to the 600's. Keep us updated.

Very nice E90 by the way