[dor1angray]

Hello fellow BMW enthusiasts!

I am running into an issue with my F32 randomly going into a limp mode and shutting down the engine shortly after. In the majority of cases, I am able to start the engine and drive after clearing the error memory.

These are all the errors from different incidents:

11A002: High fuel pressure, plausibility: pressure too low
110001: Cylinder injection shutdown: catalyst protection due to too low pressure in the fuel system
481B03: Motor current too low
11A401: High fuel pressure when injection is released: Pressure too low
11B401: High fuel pressure during or after the injection is released (2nd environmental condition sentence after time delay): Pressure too low
21A023: Combustion engine: false start or engine stopped without driver influence

After googling for a while, it was my understanding that the HPFP is the culprit and I started looking for alternatives to replace the stock one with figuring out stage 1 dorch engineering one would be the best starting point (considering I have bm3 license and will be able to code it).

Everything else in the 435i is currently OEM, no other upgrades.

Reached out to dorch engineering and they were very positive HPFP is not the reason (quote “HPFP issues are non-binary and do not get resolved by simply clearing the memory”, i.e. if HPFP breaks down, it does not recover and the engine cannot run or/and idle normally) and that it was likely EKP or LPFP suggesting I diagnose them somehow and replace either of them. Plus they noted the motor current for pump stating it could be that the EKP overheats and causes this.

Can anyone vouch on the best practice in this case? How do I figure out what’s causing it and what I should be looking at replacing first?

Taking the vehicle to the dealership did not result in any solution as they were not able to reproduce the issue (as dumb as this explanation is considering I have all logs saved for them).

Any help would be appreciated.

[thejeremyman9]

Agree with dorch, the HPFP is mechanical, so it really can't fail intermittently. So, you are back to looking at LPFP or EKP. Those are more challenging to diagnose, but are there any patterns for it, like it only happens after driving for a while, or when its hot? One thing people have done is remove the back seat area and drive with the EKP exposed to see if it still happens and if the EKP is overheated when it happens.

[fe7565]

Before you check for overheating, may want to do some fundamental checks on the EKPM. If you only have a multi-meter and no oscope, then check to make sure you read about 60 ohms between the H and L pins of the PT-CAN, connected and disconnected. Then check for average voltage from H pin to ground (should be around 2.6V) and from L pin to ground (about 2.3V).


You sure your bm3 mod is not putting too much demand on your stock fuel system where the EKPM and the pumps cannot keep up?

[dor1angray]

Originally Posted by fe7565

Before you check for overheating, may want to do some fundamental checks on the EKPM. If you only have a multi-meter and no oscope, then check to make sure you read about 60 ohms between the H and L pins of the PT-CAN, connected and disconnected. Then check for average voltage from H pin to ground (should be around 2.6V) and from L pin to ground (about 2.3V).


You sure your bm3 mod is not putting too much demand on your stock fuel system where the EKPM and the pumps cannot keep up?

Thanks for the input! No customization has been done, will only apply those once I know all hardware is running smoothly, so, no, bm3 cannot be the culprit at this point.

RE: voltage gauging, I am your fellow weekend warrior without a multi-meter and oscilloscope at hand unfortunately… Any other quick and dirty low tech way to tell between the faulty EKP and LPFP known to the humanity?

[dor1angray]

Originally Posted by thejeremyman9

Agree with dorch, the HPFP is mechanical, so it really can't fail intermittently. So, you are back to looking at LPFP or EKP. Those are more challenging to diagnose, but are there any patterns for it, like it only happens after driving for a while, or when its hot? One thing people have done is remove the back seat area and drive with the EKP exposed to see if it still happens and if the EKP is overheated when it happens.

Thanks for confirming their claims. Replacing a HPFP in N55 can easily take a whole day not to mention additional costs. The dealer quoted $2100 for the service.

The shutdowns happened mostly after lengthy trips and when climbing uphill or going downhill. I even thought the cause may be the promptly changing atmospheric pressure because this seemed to be the only pattern I could zero down on.

Regarding the overheating EKPM, there was one occurrence out of 5 when the engine died when going downhill at -10°C after only running for 5-6 minutes (plus 7-8 minutes idling while parked prior to that). It would probably not have enough time to overheat considering we attempted to start the engine for 30-40 minutes after clearing the errors, and only called towing service when we felt we were starting to freeze to death… And this was the only time when clearing errors did not help to restart the engine and we had to tow the car 80+ miles home (where it started just fine the next morning as if it thawed off).

Does this context help narrow down the symptoms?

[fe7565]

Originally Posted by dor1angray

Thanks for the input! No customization has been done, will only apply those once I know all hardware is running smoothly, so, no, bm3 cannot be the culprit at this point.

RE: voltage gauging, I am your fellow weekend warrior without a multi-meter and oscilloscope at hand unfortunately… Any other quick and dirty low tech way to tell between the faulty EKP and LPFP known to the humanity?

Harbor Freight or Walmart should have those $10 Chinese mutlti-meters. Unless you are Chuck Norris or you have $2100 to give to the dealer. may want to invest in one. Going to troubleshoot a car on your own without it is like showing up without a ring to your own wedding and expecting to hear the word "yes, I do"

The EKPM supposed to go into emergency mode if it there is a problem. In that case the low pressure fuel pump goes into a 100% drive status and operating on its own. You can try to unplug the larger connector going to the EKPM (PT-CAN High/Low, Power, Ground) and leave the other connector plugged in (that is the low pressure pump control harness).

But, if you have a PT-CAN bus issue, or any bus issue, the problem could be anywhere on that bus and may show up as an error with a component that is good but is affected.

Are those error codes you posted from ISTA?

[sqwinny]

When most people have this issue it’s due to leaky fuel injectors. Typically the n20/n26/n55/s55 have to have them replaced around the 60k mark due to them being filled with debris as there isn’t an inline fuel filter, just one in the fuel tank as the fuel filter “sock” for the fuel pump itself.

HPFP is mechanical and runs off a lobe on the camshaft, but you’d have car starting issues if the LPFP is dead/low pressure.

You can log voltage in bm3 to determine LPFP or not.

It happens but is very rare but the HPFP can leak from time to time causing replacement. But that’s rare and should have been fixed as this was more of a brand new issue with the n63 and n63tu before 2014

[dor1angray]

Originally Posted by sqwinny

When most people have this issue it’s due to leaky fuel injectors. Typically the n20/n26/n55/s55 have to have them replaced around the 60k mark due to them being filled with debris as there isn’t an inline fuel filter, just one in the fuel tank as the fuel filter “sock” for the fuel pump itself.

HPFP is mechanical and runs off a lobe on the camshaft, but you’d have car starting issues if the LPFP is dead/low pressure.

You can log voltage in bm3 to determine LPFP or not.

It happens but is very rare but the HPFP can leak from time to time causing replacement. But that’s rare and should have been fixed as this was more of a brand new issue with the n63 and n63tu before 2014

Ok this is something very new as neither dorch engineering folk nor any forums mention injectors as the culprit in this specific context. For one, I believe that EKPM vs. LPFP are being considered since the issue is intermittent and in the majority of cases is resolved by clearing the errors and restarting the car after 5-7 minutes without an issue (as of something cooled down, e.g. overheating EKP module.

Can bad/clogged injectors result in the same vehicle behavior? Would you recommend replacing OEM injectors first before looking elsewhere? If so, is there a brand/model you would particularly recommend considering I am targeting at FBO+Stage 1 HPFP?

Lastly, is the process of diagnosing EKP in bm3 described anywhere? I am very new to this. I would greatly appreciate if you could point at the manual or briefly list the steps…

Thanks a lot.

[thejeremyman9]

Your codes and symptoms do not seem to suggest injectors to me, especially since you can clear them and then proceed without issue. I am not sure about LPFP/EKP diagnosis specifically, but its probably in the service manual or ISTA somewhere.

[sqwinny]

update, after putting all those codes into this amazing resource: bmwfault.codes

This all points to your ekp. there isn't really a way to test it. a used replacement on eBay is ~ $30-40 USD. heck if you have a friend you can take it out and swap it for a good 10 minutes to see what happens.

[fe7565]

Originally Posted by sqwinny

update, after putting all those codes into this amazing resource: bmwfault.codes

This all points to your ekp. there isn't really a way to test it. a used replacement on eBay is ~ $30-40 USD. heck if you have a friend you can take it out and swap it for a good 10 minutes to see what happens.

You can test the EKP. I bought two of them on EBay before I realized that mine is not broken. So I started testing the bus and following the network instead of random troubleshooting. Found an open wire between the ESG and the GWS that knocked out both my GWS and my EKPM.

I guess $30 is not a pricey lottery ticket buying a used EKPM and see if he won. But if the OP is not mechanically inclined and not willing to invest in a $10 multimeter along with looking up diagrams, then maybe better to just drop the money and have someone fix it.

[dor1angray]

Originally Posted by fe7565

You can test the EKP. I bought two of them on EBay before I realized that mine is not broken. So I started testing the bus and following the network instead of random troubleshooting. Found an open wire between the ESG and the GWS that knocked out both my GWS and my EKPM.

I guess $30 is not a pricey lottery ticket buying a used EKPM and see if he won. But if the OP is not mechanically inclined and not willing to invest in a $10 multimeter along with looking up diagrams, then maybe better to just drop the money and have someone fix it.

Originally Posted by fe7565

You can test the EKP. I bought two of them on EBay before I realized that mine is not broken. So I started testing the bus and following the network instead of random troubleshooting. Found an open wire between the ESG and the GWS that knocked out both my GWS and my EKPM.

I guess $30 is not a pricey lottery ticket buying a used EKPM and see if he won. But if the OP is not mechanically inclined and not willing to invest in a $10 multimeter along with looking up diagrams, then maybe better to just drop the money and have someone fix it.

Thanks for the input. Several considerations:

1) Buying/replacing EKPM is not an issue. The main two issues with blindly replacing EKPM are

—not really about wasting 30-40 bucks but rather how to really test if the cause of the issue is eliminated with the new/used EKPM (the described incidents with the engine shutdowns happen very sporadically, so do I just drive, wait and hope that on the next family trip the issue does not repeat itself and we are not getting stranded on the highway?)
—how to code the new EKPM as from what I understand this is not a plug and play replacement and one needs to flash it into the system.

2) Do I rather buy a new EKPM since it is so difficult to replicate the issue that even at the BMW dealership they found no problems when clearly those are persistent?

3) Do EKPMs go bad with age without any custom LPFPs? From what I read, those only overheat when either LPFP is malfunctioning or when LPFP is upgraded putting a lot more pressure on the EKPM.

Any input on these three items would help greatly.

[fe7565]

Originally Posted by dor1angray

Thanks for the input. Several considerations:

1) Buying/replacing EKPM is not an issue. The main two issues with blindly replacing EKPM are

—not really about wasting 30-40 bucks but rather how to really test if the cause of the issue is eliminated with the new/used EKPM (the described incidents with the engine shutdowns happen very sporadically, so do I just drive, wait and hope that on the next family trip the issue does not repeat itself and we are not getting stranded on the highway?)
—how to code the new EKPM as from what I understand this is not a plug and play replacement and one needs to flash it into the system.

2) Do I rather buy a new EKPM since it is so difficult to replicate the issue that even at the BMW dealership they found no problems when clearly those are persistent?

3) Do EKPMs go bad with age without any custom LPFPs? From what I read, those only overheat when either LPFP is malfunctioning or when LPFP is upgraded putting a lot more pressure on the EKPM.

Any input on these three items would help greatly.

Generic error codes will give you generic clues. Get ISTA+ so you can pin-point the issue and also perform diagnostics on the ECUs. AT this point you can't tell if your EKPM ECU is even seen by the PT-CAN bus.

I already described earlier in great detail how to test the EKPM. I went through this recently myself, that's how I know.

If you get the correct EKPM part number, it is plug and play. In my F30 there was one part number that was "not exchangeable retrospectively", all others were. Check REAL OEM.

If for some reason you need to code the EKPM, you can use ESys, do not need a token. You do not need to flash (program), only inject the CAFD and code.

Yes, the EKPM is subject to overheating, especially if you modify the stock fuel supply. Is your EKPM overheating? You can't eliminate that possibility until you go through the steps I just outlined above.