2FCA/2FDA codes after Stage 2 LPFP install

marseille

Specialist
Jul 1, 2019
94
56
0
Ride
E61 N54
Installed a stage 2 LPFP last night. Primed the pump with ProTools before starting. Went to the gas station. Immediately noticed the car takes longer to start. Checked the codes and now have 2 shadow codes. Any ideas? Datalog below.

2FCA Fuel high pressure bei Freigabe der Einspritzung
2FDA Fuel high pressure bei oder nach Freigabe der Einspritzung

MHD v7.1 E40

Ignition Off -> Prime pump -> Start -> Idle -> Shutdown

 
Last edited:

marseille

Specialist
Jul 1, 2019
94
56
0
Ride
E61 N54
I think I've narrowed down these codes and the long crank issue to a bad fuel pressure regulator. Almost immediately upon shutting off the car, the low-pressure fuel sensor drops to 3 to 5 psi on its way to 0 and the rail pressure drops significantly in the 20's on its way lower. Before starting the car, watching the fuel pump prime also shows very little fuel pressure being built by the low-pressure fuel sensor. It's not until the long crank builds up enough low-pressure to help build the rail pressure up to fire off the engine.
 
  • Like
Reactions: Orion1two

marseille

Specialist
Jul 1, 2019
94
56
0
Ride
E61 N54
Here's another example. Car sat overnight. Inserted the key for ignition on (fuel pump primed) and did not start the car. Here's what happened in 20 seconds:

 

doublespaces

Administrator
Oct 18, 2016
9,303
4,331
0
AZ
Ride
2009 E93 335i
Interesting. You could also have a bad HPFP. I'm pretty sure there is a mechanical relief valve inside that alllows pressure bleed out and return back into the LPFP system. Also, your rail pressure dropping in the first log seems normal, I think it tries to target somewhere around 700 PSI at idle.
 
  • Like
Reactions: Orion1two

marseille

Specialist
Jul 1, 2019
94
56
0
Ride
E61 N54
Unfortunately, I think you are on the right track. I replaced the 50K FPR/Fuel Filter with a new OEM. That didn't solve it. The current behavior is like my last graph. If I prime twice it fires off ok. Otherwise, it's a LONG crank. Can the relief valve be replaced or do you have to replace the entire unit? Bummer if not, because the datalogs (PSI) seem good for the HPFP.
 

doublespaces

Administrator
Oct 18, 2016
9,303
4,331
0
AZ
Ride
2009 E93 335i
Unfortunately, I think you are on the right track. I replaced the 50K FPR/Fuel Filter with a new OEM. That didn't solve it. The current behavior is like my last graph. If I prime twice it fires off ok. Otherwise, it's a LONG crank. Can the relief valve be replaced or do you have to replace the entire unit? Bummer if not, because the datalogs (PSI) seem good for the HPFP.

It is not serviceable afaik.
 

matreyia

Major
Apr 19, 2017
1,780
711
0
Ride
335i e93
Unfortunately, I think you are on the right track. I replaced the 50K FPR/Fuel Filter with a new OEM. That didn't solve it. The current behavior is like my last graph. If I prime twice it fires off ok. Otherwise, it's a LONG crank. Can the relief valve be replaced or do you have to replace the entire unit? Bummer if not, because the datalogs (PSI) seem good for the HPFP.

Replace high and low pressure fuel sensors first. Most people don't even think about this and they go on to replace expensive pumps when they should have performed best practice and replaced both sensors when they upgraded parts of the fuel system.

Regardless of a good or bad HPFP, you will need to replace both sensors anyways, so do that first before buying the HPFP.
 
  • Informative
Reactions: marseille

Jeffman

Major
Jan 7, 2017
1,618
1
628
0
Replace high and low pressure fuel sensors first. Most people don't even think about this and they go on to replace expensive pumps when they should have performed best practice and replaced both sensors when they upgraded parts of the fuel system.

Regardless of a good or bad HPFP, you will need to replace both sensors anyways, so do that first before buying the HPFP.
What’s a tell-tale sign that the LPFP sensor needs to be replaced? I installed the BPM4 and my LPFP values are still jumping wildly.
 

matreyia

Major
Apr 19, 2017
1,780
711
0
Ride
335i e93
What’s a tell-tale sign that the LPFP sensor needs to be replaced? I installed the BPM4 and my LPFP values are still jumping wildly.

There is no tell tale sign. Sensor failure mimics pump failure. You cannot tell which one it is. That is why it is best practice to replace the sensors when touching the hpfp or lpfp. Otherwise your assumption that the sensor are good may lead you down a rabbit hole. Nip it in the bud all at once. Just like you replace rotors AND pads each time your pads wear out, so too should you replace related sensors when you replace a sensor dependent device such as any oil or fuel pump. This will save you time, money and headaches if you just follow this recommended maintenance habit....even though it may APPEAR that you might be wasting money on a seemingly good sensor.

Of course common sense dictates that you should NOT change the sensor if you just replaced it oem brand new.

Once I bought a supposedly new sensor from a place online and it was doa. I vehemently denied that it could possibly be the issue until I wasted two weeks replacing every single part I thought was the issue and in the end I ordered a new sensor from fcp euro and lo and behold it was the damn doa sensor that was the issue. Uneven fuel delivery even though I replaced pumps, lines, ekpm...

I say this from experience and NOT guessing. But do as you believe if that makes you more at ease.

Actually I replaced both my sensors when I upgraded to stage 3 lpfp and bmp4 controller a few months ago. Zero issues.
 
Last edited:
  • Like
Reactions: Jeffman

Jeffman

Major
Jan 7, 2017
1,618
1
628
0
There is no tell tale sign. Sensor failure mimics pump failure. You cannot tell which one it is. That is why it is best practice to replace the sensors when touching the hpfp or lpfp. Otherwise your assumption that the sensor are good may lead you down a rabbit hole. Nip it in the bud all at once. Just like you replace rotors AND pads each time your pads wear out, so too should you replace related sensors when you replace a sensor dependent device such as any oil or fuel pump. This will save you time, money and headaches if you just follow this recommended maintenance habit....even though it may APPEAR that you might be wasting money on a seemingly good sensor.

Of course common sense dictates that you should NOT change the sensor if you just replaced it oem brand new.

Once I bought a supposedly new sensor from a place online and it was doa. I vehemently denied that it could possibly be the issue until I wasted two weeks replacing every single part I thought was the issue and in the end I ordered a new sensor from fcp euro and lo and behold it was the damn doa sensor that was the issue. Uneven fuel delivery even though I replaced pumps, lines, ekpm...

I say this from experience and NOT guessing. But do as you believe if that makes you more at ease.

Actually I replaced both my sensors when I upgraded to stage 3 lpfp and bmp4 controller a few months ago. Zero issues.
Thanks. Can you share a datalog of your latest setup? It sounds like everything is working well on your car and I’d like to compare how your fuel pressures compare to mine with BPM4 Stage 2 LPFP, but with old original 2008 sensors. Thanks.
 
Last edited:

matreyia

Major
Apr 19, 2017
1,780
711
0
Ride
335i e93
Thanks. Can you share a datalog of your latest setup? It sounds like everything is working well on your car and I’d like to compare how your fuel pressures compare to mine with BPM4 Stage 2 LPFP, but with old original 2008 sensors. Thanks.

You have NEVER replaced your sensors? Dude. That is insane. They go bad all the time.
 

matreyia

Major
Apr 19, 2017
1,780
711
0
Ride
335i e93
Thanks. Can you share a datalog of your latest setup? It sounds like everything is working well on your car and I’d like to compare how your fuel pressures compare to mine with BPM4 Stage 2 LPFP, but with old original 2008 sensors. Thanks.

Your graph looks like mine did before replacing the controller and the sensors. You need to replace BOTH of your sensors. Even if ONE is not 100% functional, it won't matter what new controller you use...the controller depends on the health of the sensors. So you will get incorrect pressure data to the controller and result in erratic pumping. Just change the sensors. As for making a log... there is no need to log, you would only see my log as looking ultra smooth and it would do nothing for your situation. Imagine a normal smooth log.... if I were to do one right now...that's what you would see. There is no point in doing a log. Just take my word on it. My car is performing indistinguishable from stock straight from the dealership on day one.
 

Jeffman

Major
Jan 7, 2017
1,618
1
628
0

matreyia

Major
Apr 19, 2017
1,780
711
0
Ride
335i e93
You may be right. I may be crazy. Or it just may be the lunatic you’re looking for...
So I’m taking a poll :)

You changed your pumps? You changed your controller...and you still got issues. You did not ever change your sensors.... I bet you a corndog that you need to change them sensors...both of them.
 
  • Funny
Reactions: Jeffman

matreyia

Major
Apr 19, 2017
1,780
711
0
Ride
335i e93
This guy has a failing LPFP

There is a revised updated LPFP Sensor FYI. If you have the brass version that is obsolete.

This guy has a good LPFP still, note the pressure.
 

matreyia

Major
Apr 19, 2017
1,780
711
0
Ride
335i e93
Thanks. Can you share a datalog of your latest setup? It sounds like everything is working well on your car and I’d like to compare how your fuel pressures compare to mine with BPM4 Stage 2 LPFP, but with old original 2008 sensors. Thanks.

Think about your graph here...
1. If you had a bad LPFP - which you know is not the case because you installed a new stage 2 unit, then it would not hold pressure. Here it makes pressure, then goes away, then repeats. The graph shows a voltage sending that is trying to match data from a faulty sensor imo. If you give the controller false data, it will send the corresponding voltage. Since the controller is new, the stage 2 is new... and you are getting these spikes, most likely the controller is sending voltage based on sensor data.

2. If you have a bad sensor... who knows what it sends or how consistent it sends? All I know is once I changed my sensors, everything was ultra smooth and fuel economy got higher. And I didn't even think I needed new sensors, I just replaced them as preventive maintenance.

When both sensors were replaced and I still got spikes, it was before the BPM4 controller was installed and port injection was activated via hobbs switch...which is totally inaccurate due to charge pipe gross fluctuations in pressure. Once both the sensors and the controller unit was replaced...it's been smooth as ice. Only shifting still needs to be tweaked due to increased power.

If you have a bad LPFP Sensor, it will affect the HPFP sensor on the fuel rail...a chain reaction because they are both on the same system. It could be one is good and the other is bad...but you cannot tell which one, so you should do both to eliminate doubt. If you have new stage 2, new BPM4 controller, and both sensors replaced, then you know it is most likely the HPFP. and that would be the end of the line in terms of mysteries. It is cheaper to do both sensors than go replace the HPFP and ignore the sensors...which means, you will still have the same issues because you didn't follow best practice and you chose to keep the original sensors.
 

matreyia

Major
Apr 19, 2017
1,780
711
0
Ride
335i e93
Just so I am not blindly suggesting things...

1. Did you reset throttle adaptations?
2. Did you follow proper waiting time with key in ignition in accessory 'on' position (30 seconds before starting engine)