2013 E70 X5 35i N55 fuel issue

[andrewwynn]

I think you can command the lpfp on but won't be able to read the fuel pressure at the same time.

I think n55 won't prime until you hit start but may of you hit start without the brake pedal down.



18-17 Mpa full throttle. 2600. 101.5 psi low pressure pump.

I'd get an actual gauge on the low pressure and figure out if your sensor is sending bad data.

[rvaughnp]

Originally Posted by pshovest

Does the engine run at all?
Put 2 gal of gas in tank to rule out a tank level gage problem.
Remove and reinsert all coil connectors.
I think "rail pressure" is the measured value and "nominal value" is the target/expected value. Your fuel pressures seem low.

N55 may be different, but when I unlock my E70 N52 or open door after being asleep, the fuel pump primes. We need to confirm the LPFP is delivering ~5barg. Check fuel pressure after unlocking and before cranking using scanner. If you can't see it thru scanner, my N52 has Bundy fittings near brake booster that allow a pressure gage to be connected to the LP side of the HPFP.

Does Foxwell allow you to run the LPFP?

It'll run, but poorly at first and then go to limp mode where it will idle decently but reving it "bogs". You can hear it in the videos.
I have heard differently on the opening door with this year model N55.
Foxwell does read and the measurement I have taken shows: 680 kpa / 98 psi "Fuel Pressure (low pressure).

[rvaughnp]

Originally Posted by andrewwynn

I think you can command the lpfp on but won't be able to read the fuel pressure at the same time.

I think n55 won't prime until you hit start but may of you hit start without the brake pedal down.


18-17 Mpa full throttle. 2600. 101.5 psi low pressure pump.

I'd get an actual gauge on the low pressure and figure out if your sensor is sending bad data.

Yes on the priming. I have searched and found the same on this yr/model. It does not prime on door open or other. It is - key on start/ power on.
I'm reading 98psi with my foxwell. Purchased an actual oem HPFP sensor so we'll see if that changes anything.

[andrewwynn]

I wonder if there are multiple sensors. I have two readings in my foxwell under the high pressure and they both track almost identical. What do you see?

Graph the low pressure and make sure it's dead flat.

[pshovest]

Are there any other codes after engine "bogs" and goes into limp mode? Strange that this occurs when it didn't before valve cover replacement.
Read codes while in limp mode w/o turning off ignition.
Remove and reinstall coils to make sure they are fully seated.
ETK shows there are two sensors, high & low pressure. Both sensors should read the same before starting the engine. If they do, they are likely OK as I wouldn't expect both to have problems.
98 psi seems OK, based on AW's post, but reading is only as accurate as the LP sensor. A bad LP sensor that reports higher than actual fuel pressure will cause HP problems.

Force the LPFP to run w/Foxwell and CAREFULLY crack the HPFP and injector fuel lines to purge them of air.

[rvaughnp]

Originally Posted by andrewwynn

I wonder if there are multiple sensors. I have two readings in my foxwell under the high pressure and they both track almost identical. What do you see?

Graph the low pressure and make sure it's dead flat.

I don't believe there is a LP sensor. At the tank pump there are the 2 wires powering the pump and 2 for the level sensor.
With that said... my Foxwell is reading a LPFP reading of constant 98.6 psi with motor not running and with motor running! figure that one out!!!
https://youtu.be/pLk7BJmd9hk

Thats why I was asking about the two identical readings. If you are sure, I would like to know.
My understanding is the nominal press is "desired" and the other is actual pressure being read.
The fact that my rail pressure is staying the same while the nominal is changing doesn't make sense.
I have ordered a BMW sensor and paid to expedite, so hopefully itll be here by Wed and I'll if that changes anything.

[rvaughnp]

Originally Posted by pshovest

Are there any other codes after engine "bogs" and goes into limp mode? Strange that this occurs when it didn't before valve cover replacement.
Read codes while in limp mode w/o turning off ignition.
Remove and reinstall coils to make sure they are fully seated.
ETK shows there are two sensors, high & low pressure. Both sensors should read the same before starting the engine. If they do, they are likely OK as I wouldn't expect both to have problems.
98 psi seems OK, based on AW's post, but reading is only as accurate as the LP sensor. A bad LP sensor that reports higher than actual fuel pressure will cause HP problems.

Force the LPFP to run w/Foxwell and CAREFULLY crack the HPFP and injector fuel lines to purge them of air.

I am getting 2BEE High Fuel Pressure, plausibility, cold start: Pressure too low.
I have check the coil and they are seated, have checked the injector plugs, seated.
Not sure where you are getting the LP sensor.
Not sure why one would have to "purge" air out of an injector that opens and closes on command. They are self purging. And, I've had the car running.
"Force the LPFP to run w/Foxwell..." it's not going to push past the HPFP into the injector lines. I have put 12volts to the LPFP and "bleed" the line, just to make sure it was working. But again, its not going to push pressure through the HPFP into the fuel rails. And.... I've had the car running. No way is there still air in the lines.

[pshovest]

Deleted.
On second look at the ETK, the LP sensor ended with the 2012 model (4/12 production). Not sure how the 98 psi is being read or measured.

[rvaughnp]

Originally Posted by pshovest

Deleted.
On second look at the ETK, the LP sensor ended with the 2012 model (4/12 production). Not sure how the 98 psi is being read or measured.

My yr /make has the spring/diaphragm HPFP not the mechanical one. There is definitely not a sensor on the incoming line on my car.
Yeahhhh… I’m really not looking into the LPFP thing.
My question goes back to the difference in Rail Pressure / Nominal pressure and reg Rail pressure and what would cause them to not be similar?!

[andrewwynn]

Something is very weird about that 98.6 or my case is 101.5. Itt never changes.

So I found something likely more useful..






Fuel pump voltage and volume. See what you find. The peaks were heavy throttle to 40 mpg.