[Sweden]

Hi!

So this is my first post as I thought I could use some help from you guys. So til now I have been googling and reading a lot but have not yet desired what to do. Prepare for a quite long post incl. recording.

I have a problem with my high pressure fuel supply.

Fault codes:
29F2 - Fuel high-pressure system, fuel pressure
2FBF - Fuel pressure on release of injection

When does the fault appear?
It can happen anytime with even load on highway or under heavy load with low RPM.

How often does it happen?
It varies, sometimes I can drive for a thousand miles, sometimes five miles.

What happens?
The first thing I notice is the half engine light with LIMP mode (29F2). The car jerks once, probably from switching from high to low pressure. I'am able to keep driving. But when pressing the throttle there is a long delay before it accelerates. When I depress the clutch, the engine often shuts of like there is no idle. It is really hard to drive but it is possible if keeping the throttle pressed at all times. It jerks a lot and with a long delay every time I press the throttle. There is no problem starting the engine after a stall. Still with same problem thought. Sometimes it can be driven normally after a restart (in LIMP mode).

I screen recorded INPA last time it happened. The recording starts with a start up after it stalled. As we can see the high pressure varies a lot and not stable at 200 bars as it should be. The low pressure is quite stable I would say?


First the engine is started after it stalled a few minutes before the recording.
0:05-1:10 idle and small touches on throttle.
1:10 starts driving carefully
1:16 enters LIMP mode
1:23-1.33 idle
1:33-1:52 driving

My quess is the HPFP, maybe more specific the quantity control valve, as the high pressure is unstable, but the low pressure is fairly stable. But after reading at bimmerprofs were he claims 99 out of 100 the HPFP is not the cause, then I feel that I want to be more sure since the HPFP is quite expensive.
I feel like it's a bit odd that it runs so poor efter the HPFP has been disengaged though, could it be the control valve that is "loose" and disturbes the low pressure even thought it's powerless?
Or could it even be leaking injectors? But the two codes above are the only ones and I have no missfires from what I can tell.

Most often I can just reset fault memory and it's back to normal again, with perfect pressures in high and low pressure system.

About 8000 miles ago I changed 3 injectors in one bank to index 11, the other 3 are index 7 and index 2. At that time all injectors were fine. I also changed all sparkplugs. 1800 miles ago I mounted a Noxem 129 from bimmerprofs and readapted engine. 1200 miles ago I installed a new AGM battery. All original BMW spare parts except Noxem. First time I had 29F2 maybe 2000-2500 miles ago.

Any help would be much appriciated, I can get more INPA or ISTA readings if needed.

Thank you!!

[R3V0K3D]

Hi, have you fixed this problem? Im getting exactly the same stuff as you're getting with my dads e93 325i n53, HPFP has been changed, injectors too including Low pressure sensor.

[0l0dom0l0]

Originally Posted by R3V0K3D

Hi, have you fixed this problem? Im getting exactly the same stuff as you're getting with my dads e93 325i n53, HPFP has been changed, injectors too including Low pressure sensor.

Did you use a genuine HPFP and how long ago was it replaced?

[R3V0K3D]

Originally Posted by 0l0dom0l0

Did you use a genuine HPFP and how long ago was it replaced?

Hi, sorry for late reply. Around a year ago - the previous owner said that its an not original pump (HPFP), I also replaced both of the rail sensors with OEM ones from BMW directly. ISTA diagnose showed no problems with HPFP so im out of ideas.

[Will_460cs]

non genuine pumps are junk. best to replace - you cam verify with live data

[R3V0K3D]

Originally Posted by Will_460cs

non genuine pumps are junk. best to replace - you cam verify with live data

In ISTA? Do you know where can I monitor, or do I need to check it with INPA? Got both.

[0l0dom0l0]

Replace with a genuine pump and the fault will be fixed.

[Will_460cs]

Look under fuel pressures you should be at 200bar - but it’s a guaranteed fail if a non genuine pump has been used / Asia rebuild.

[Will_460cs]

Just google your error codes the fault is explanatory in this case;


Diagnosis shows fault code 29DC (Cylinder injection cut-out, pressure too low in high-pressure system) and/or 2FBF (Fuel pressure on-release injection, pressure too low), and in some cases, also in conjunction with 29F1 (Fuel high-pressure, plausibility) and 29F2 (Fuel high-pressure, fuel pressure undershot)


Personally I always change low pressure fuel pump at same time as high pressure as this is best practice (unless already replaced), this will change the only fuel filters that are present in the system as they are in the lpfp.

[R3V0K3D]

I see. I have scanned it with another tool, the thing is that when the car gets in limp mode, the sensor reads 5bar - before that its 200bar all the time (or atleast around +/- few bars). At 5 bars, the car wouldnt even run... Ill try with the LPFP first, and then ill report back, as I dont think that its been ever replaced. Thanks guys.