[Warishuku]

Hello guys good day.

First of all, I really, REALLY tried to find a post with the same issues that I have (I used the search function and never showed up), so if there is a post or sticky with the same issues, I'm really sorry for not being able to find it, and please, feel free to share the link of that post.

OK here is the thing: I've been chasing an ignition issue on my 335i E92 '08, and now I'm in a point that I need your help in order to determine if the problem is HW or SW related.

A little background info:
-I bought this car last february 28th, completely bone stock, 110k km (almost 69k miles, very low! ).
-The car had an slight frontal impact, but no mechanical damages, only headlight damage (Bye bye adaptive headlights ) and the left headlight arm support broke. It is already fixed.
-The car has a rough cold start issue, it hesitate for about 15-30 seconds and the rpms goes up and down between 900-200 rpms. Sometimes it doesn't make it and dies. After this rough start, the cart idles normally.
-Checked with INPA and had several codes, basically VANOS solenoids being mechanically stuck and 2 codes for O2 sensors heaters not being activated (Bank 2 pre-cat and bank 1 post-cat)
-After detecting this issues I changed the oil and oil filter, changed O2 sensors with the faulty codes, bought new spark plugs (Autolite ones recommended in one of this forum topics, the ones that are 1.5 colder), new Delphi coils, put 3" VRSF DPs, changed both vacuum solenoids, changed vacuum lines, changed FMIC to a 7.5" VRSF racing one, changed charge pipe for a metal one, put DCI, the car is basically FBO and is waiting a fix in order to be tuned with MHD.
-After all this changes, the car behaves the same, only the VANOS solenoids codes were fixed because I cleaned them, the O2 sensor ones still appeared, so the problem was either in the harness of the O2 sensors or the DME itself.
-Sometimes I used to get a lean code in bank 1.
-Yesterday I bought the MHD monitor add-on because my INPA has some errors and it doesn't let me monitor in real time. Looking at the data (AFR, STFT, LTFT, fuel rail pressure, low side fuel pressure) I discovered that basically bank 2 was in open loop because AFR was stuck in 14.68 and both fuel trims stuck at zero. Bank 1 behaved ok.
-So after this I checked the DME and found out that in the connector X60002 had the #13 pin bent (Bank 2 pre-cat heater) and it also bent #26 pin (Bank 1 post-cat heater), so that was the culprit of my O2 codes, after fixing the pins, both codes disappeared and now both banks are in closed loop.
-After this fix, the car still cold starts bad, but now I'm getting high pressure fuel codes and the car is getting in limp mode almost instantly.

Ok after all the mess written above, I want to go with the actual situation and I would like to have some feedback of you guys:

-Looking at MHD monitor, when I start the car I discovered that the fuel rail is not getting more than 80 PSI, when it is supposed to have like 700 PSI at idle, after several seconds idling the car gets in limp mode (half engine alert, engine fans at 100%, etc) because of low fuel rail pressure (Code 29F2, some times I get 2FBE and 29DC, and I have shadow codes 2FCA and 2FDA).
-When it gets in limp mode, I noticed that basically the HPFP gets skipped by the DME because both low pressure sensor and fuel rail pressure sensors reads exactly the same 82+-.02 PSI at idle.
-OK THE WEIRD THING IS: if I reset all the adaptions, the car gets in open loop for a good period of time, and the fuel rail pressure gets to nominal since start of the engine (it gets up to 2000 PSI and gradually it gets back to 680-720 PSI at idle).
-I can drive the car in open loop and the pressure is normal for a good period of time, but after some time it eventually gets down to 80-100 PSI, but not exactly as the low pressure fuel sensor like in limp mode. The car does not get in limp mode when it is in open loop.
-It looks like that when the car is in open loop, the car never gets in limp mode because of low fuel pressure, and it makes me think that probably the bent pins of my DME were an intentional job in order to avoid limp mode.
-After the test ride in open loop, when the rail pressure drops to 80-100 PSI, I park the car, reset the adaptions, and the car gets again the right amount of pressure in the rail (680-720 PSI).

So, after all this mess, I'm not quite sure if the problem in the rail pressure is exactly a mechanical issue, it seems that the problem could be software related, but unfortunately I don't understand the HPFP and how it works electronically (I understand that it is a mechanical pump), so I don't know if it has an electronic module that could be bad instead of some mechanical component like a seal or valve.

So, for me the problem could be the HPFP or some SW problem because:

-Low Pressure Fuel Sensor: It seems to work right, it gets up to 72 PSI when the LPFP gets primed, and at idle it gets up to 82 PSI.
-Fuel Rail Pressure Sensor: It seems to be OK, it detects correctly when the pressure gets up in the rail (I can hear the tick noise of the injectors change when the pressure gets up in the rail), and also when the HPFP gets bypassed by the DME, it correctly reads the same pressure as the low pressure fuel sensor.
-Injectors: I don't think that these are the culprits, I have no misfires at idle or under aceleration.

Here are 2 logs that I recorded this morning:
-The first one is a cold start without a reset of the adaptions, so the car is working at closed loop. You can see that the car dies at the very beginning because of the bad idle, and after a second start the car hesitates a lot, the fuel rail pressure never gets up and eventually gets in limp mode:

Cold Start - No Adaptions Reset


-The second one is a "warm" start (more cold than hot IMO) but after a adaptions reset. You can see that it is at open loop (AFRs at 14.68, and fuel trims at zero) and look how the pressure gets up correctly. After a short driving period, the fuel rail pressure drops to 80-100 PSI, never gets in limp mode. If I start the car again, the pressure never gets up. If I reset again adaptions, the pressure gets up again in the next start.

Warm Start - Adaptions Reset


Please, any feedback or comments are very valuable. I know that the easiest way is to change the HPFP, but I don't want to be in a situation that a new HPFP doesn't fix the problem (Those are very expensive here) and because of that waste money in a problem that probably is SW related and probably free of charge to fix.

Thanks a lot!

[Warishuku]

Ok I have an update about this topic.

I ran a new cold start (7 hours after the car was turned off) but this time with the adaptions just refreshed and I found something interesting about it.

Cold Start - Adaptions Reset

Ok the car started like crap as usual, something interesting is that the fuel rail pressure remained low in the 80's PSI during the cold start, but after the cold start procedure finished, the fuel rail pressure started to rise to the nominal point of 680-720 PSI.

Looking at the data, one interesting variable is the Fuel Mode:
-With the ignition On (but not started) the Fuel Mode is 2.
-Just at the beginning the Fuel Mode changes to 4, and almost instantly changed to 5. In the middle of the sequences it changes back to 4.
-Almost at the end of the start up sequence, it changes to 10.
-Finally at the end it changes to 2, and it is at this moment when the fuel rail pressure starts to rise, and the RPMs stabilized (In this moment is when you hear the exhaust "opening").

Does anybody knows what are this Fuel Modes? is there a chart or something?

Thanks!

[IllSic_Design]

Taken from another BMW board not allowed to be linked to

Mode 2: "Regular" fuel mode. This is the one that is used during typical driving. I don't know if there is a better technical name fore it.

Mode 20: Spool mode/lean spool.

Mode 10: Start up enrichment.

6 is the cat protection mode too BTW.

So what is mode 15 for? "I believe it is "open loop""







Taken from MHD manual:

– (20 spool mode, 2 normal fueling mode, 6 Cat protection fueling mode, 10
warmup/open loop fuel mode)

[Warishuku]

Originally Posted by IllSic_Design

Taken from another BMW board not allowed to be linked to

Mode 2: "Regular" fuel mode. This is the one that is used during typical driving. I don't know if there is a better technical name fore it.

Mode 20: Spool mode/lean spool.

Mode 10: Start up enrichment.

6 is the cat protection mode too BTW.

So what is mode 15 for? "I believe it is "open loop""







Taken from MHD manual:

– (20 spool mode, 2 normal fueling mode, 6 Cat protection fueling mode, 10
warmup/open loop fuel mode)

Thanks for the input, I'm still wondering what does Fuel Mode 4 & 5 means, because those 2 are the ones that were active during all the hesitation and I suspect that they have something to do regarding at the fuel pressure not rising at all... Hopefully this is a management issue and not a bad HPFP.

[IllSic_Design]

I could not find any info on fuel modes 4 and 5. I would ask one of the tuning companies/people as they will know a lot more about the DME and what it can do/has for settings

[Warishuku]

Ok I have some news:

I did update almost all the vehicle modules (DME, DSC, FZD, etc. etc.), and after fixing codes with tool32 and NCS Expert, I started the car with all the new SW available.

The car started perfectly in closed loop (AFR, Fuel Trims active on both banks), the rail pressure went up to 2500+ PSI at cold start and it eventually went back to 680-720 PSI at idle.

I gave it a quick ride, but eventually after a couple of minutes the HPFP dropped to 80-100 PSI, and limp mode was activated. It is important to say that this drop happened just after a deceleration (slowing down without using gas, AFR at 234.95 and Trims at 0).

I did several decelerations without using gas and not in all of them the pressure dropped like that.

I'm really confuesed, the HPFP seems to deliver the pressure without any problems (mechanically-wise speaking), but it seems that something cuts the pressure delivery to the fuel rail, and I don't know if there is an electronically controlled valve o something inside that could be having issues, or maybe there is a bad signal being delivered to the HPFP and reduces the pressure at minimum.

Please check my log and if you have an idea of what could be happening please let me know.

LOG:
Cold Start - New Flash

Thanks!

[Warishuku]

Hey guys good day! I hope everyone is good and healthy during this hard days.

Ok, I've been researching about all this issue that I have, and because I don't want to spend in a whole new HPFP with the risk of not solving the issue (This in case that the problem is in the DME signals to the HPFP) I've been looking for more specific solutions to this problem.

First, take a look at this amazing articles about how the HPFP for the N54 and newer BMW's (and some Mini's) work:

Bimmerprofs - HPFP
newtis.info - Quantity Control Valve

It seems that the problem (If not DME related) is located in the Quantity Control Valve, either by a dirty/stuck solenoid, or with leaky O-Rings.

THE PICTURE IS NOT MINE.

Does anybody here knows the size of the O-Rings? I think that I can do some testing and see if the problem gets fixed with a couple of new O-Rings and some cleaning with carb cleaner inside the solenoid.

Thanks!

[Warishuku]

Ok several updates...

I removed the solenoid from the HPFP, electrically it works as intended and physically it seems to be good, the o-rings are good looking and looks very clean, anyways I put some carb cleaner in the solenoid just in case.

I put it again in the pump, primed several times the LPFP and started the car. The car started "fine" (no hesitation but not as smooth as it should be), the pressure in the rail went up to 2500 PSI, then 2100 PSI, and after some seconds it came back to 700 PSI.

I noticed that the pressure didn't rise as quick as it should be, looking at logs from healthy HPFP's, the rail pressure maximum tops just at the moment the car starts (like in the first second after cranking), and mine as a flatter curve over time, but it eventually gets to the 2500 PSI (See my latest log in this thread).

It worked well at idle, but when I rev it up to 3k-5k rpms, I noticed that the pressure in the rail didn't increase at all, actually it dropped to 300-400 PSI, the first times after the idle stabilized the pressure went up to 700 PSI, but after several tries it eventually collapsed to 80-100 PSI, after that it went to limp mode and finally the pressure drops to LPFP levels.

I now changed both high and low pressure sensors (as sanity check before paying for a new HPFP), but the behaviour is the same.

I'm completely confused... it seems that the issue is in the fuel management, I don't know... I think that if the issue is mechanical then the failure won't be the way I'm having it.

I know that I'm literally speaking to myself here, but if anyone have any comment or experience with this issue I'll really appreciate any kind of feedback.

Thanks!

[Mustafa.e92]

Did you end up figuring this out? Have the same issue about to pull the trigger on a new hpfp

[Warishuku]

Originally Posted by Mustafa.e92

Did you end up figuring this out? Have the same issue about to pull the trigger on a new hpfp

Hey! Sorry for the late response.

I ended up changing the whole HPFP, and the problem was fixed

I bought it at FCPEuro so I have lifetime warranty, in case of a new failure I just have to pay for the shipping of the old one and the shipping of new one.

I hope this helps.

[135i_vs_]

Originally Posted by Warishuku

Hey! Sorry for the late response.

I ended up changing the whole HPFP, and the problem was fixed

I bought it at FCPEuro so I have lifetime warranty, in case of a new failure I just have to pay for the shipping of the old one and the shipping of new one.

I hope this helps.

Thanks for posting! I am having a very similar issue and having a hard time figuring out the problem. 2008 335i.

-Changed coils
-Changed plugs
-Changed all 6 injectors to remanufactured ones
-Changed LPFP
And the problem still persists.

My question is, is the HPFP supposed to do this at cold start idle (see attachment)? Literally dropped from 1,500 psi to around 500 psi. A soon as the pressure dropped the car starting misfiring at idle.
Do you have healthy HPFP graphs to share?

Thanks for your help!