Fueling issues on N54

[Ismail.B]

Hey guys.

Been having some issue with fueling on my 135i over the last few months, car would splutter on every hard pull, felt like she was starving for fuel, did some logs had some assistance in diagnosing and ended up changing lpfp to the warlbro 450, after this lpfp seemed to be holding up but rail pressure was dipping, replaced hpfp with new OEM hpfp. Since then she ran perfectly fine for some time, until a week or two ago, was pulling through 3rd and felt a tiny splutter which happened but recovered very quickly during the pull, tried to do some logs but it didnt happen again for a while, a few days ago it happened again during a pull in 4th, this time after trying to replicate it in the log i managed to get it in, seems like fuel pressure dips on the hp side for some reason and thereafter recovers - also throws a shadow code of superknocking in multiple cylinders when the dip occurred. The code gives me nightmares, i have stop using the car. :hammerhead:

Anybody tackle an issue like this?

i do have an 08 135i, could it be my ekp?

Mileage 125k, all maintenance up to date
Downpipes, inlets, dci, warlbro 450, custom tune

 

[Woodies]

Faulty knock sensor maybe? Not sure how to test it tho........

 

[osiris]

So this sounds very similar to an issue I was having.

I thought my hpfp was taking a kak, it eventually got so bad my car would stall if I was stuck in traffic, I would get an error on idrive "fuel pump error, car might stall" and shortly after getting that message the car would stall.

It threw hpfp codes, so I got a brand new hpfp and the problem was still there! someone mentioned EKP module to me so I did some research and so did a buddy of mine and we found that the mosfet chip on the EKP module overheats, I fitted a heatsink to that chip and dremeled holes into the module plastic casing and fitted a cpu fan to it and haven't had the issue since.

Now for your fueling issue in your logs. I also had that issue and I will give you a run down of what happens on my particular car.

I used to run MHD stage 1 and from time to time the stage2+ software on my car and my fueling was spot on. very high rail pressure during pulls.
I then recently fitted a JB4 to my car and loaded the cars stock software and ran some logs with just the jb4 and my hpfp reading on the car is high during a wot pull, in jb4 logs it reads 17 - 18 all the way through the log, Which is great for wot at around 18psi

Now as soon as I load a BEF to the car via mhd, just one of the ots bef from bms the car pulls hard but the first thing I notice is my hpfp readings during a wot pull are low, 11 and 10 and sometimes drops to 9 during a pull in which case I will get big timing corrections in some of the cylinders for that split second that the hpfp pressure dips below 10. obviously this is due to leaning out.

I have no idea why this happens, something in the way these bef are written are not gelling with my car so well, I have a z4 N54 and bmw made a few changes like no lpfp sensor and a few other changes here and there so its never as simple as just writing a map to the car and driving off.

I have no idea if this is perhaps what may be happening to your car but I can tell you this much. The new hpfp has made very little difference as this was the EKP module that was causing hpfp codes and the low rail pressure seems to be software related.

 

[Twinz]

Post up the log...and the actual code:thumbs:

 

[Ismail.B]

Eish, sounds like you've had your fair share of kuk.

Someone also mentioned to me to check out the ekp, as the overheating was the cause of his issue (similar to mine) and he didnt have luck with changing Ekpm2 to Ekpm3 and eventually bought a torqbyt ekpm which apparently solved his issue.

With regards to software, i have been in constant contact with my tuner, discussing issues and sending logs, he has been helpful with making changes and fault finding. The unusual thing on this one is that it is intermittent. i can do multiple pulls today and she will pull strong and smooth, try the same thing on another day and in 1 of the pulls i may get this sputter.

but i am going to look into any advice i can get right now, just been a long haul so far!

Maybe i might be missing something in the logs

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https://datazap.me/u/ismailb/splutter-during-wot-new-hpfp-and-upgraded-lpfp?log=0&data=22

Here is a log, thanks!

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[osiris]

I have the EKPM3 module and it makes no difference. See the thing with these modules is the EKPM3 module has already got a big heatsink but its a badly designed heatsink and its bolted straight onto the body of the car hidden under a bunch of carpets so the heatsink is soaking up the heat but can't do anything with it. So I put a ribbed heatsink on the mosfet chip itself as well as put cpu heat paste on the back of the main modules heatsink so as to dissipate heat into the metal of the car that its bolted to more efficiently.

The next thing to note which I forgot to mention is that the reason the EKP module starts to over heat is because you and I both have a warlboro 450 lpfp which draws more current and thus puts the EKP Module under strain. However it takes time for the symptoms to appear, we talking years in some cases. The EKP Module needs to be coded if your running after market high power lpfp's as it needs to be told to dish out more current. I haven't done this and I am assuming you haven't either.

But this probably isn't your issue, I was just outlining a few points about the EKP module.

Some people though have had low fuel pressure during wot pulls due to the EKP Module so don't rule it out.

 

[Ismail.B]

Thanks for shedding some light, definitely broadens my understanding of the ekpm, i guess its back to the drawing boards! and yes, no coding has been done, i still have the oem ekpm2 on mine.

Not ruling it out but from what you have said and i have understood, it sounds unlikely to be the ekpm thats causing my problem

 

[NAS325ci]

Leaking injectors

 

[Twinz]

Those are serious shadow codes.

When you say tuner i assume you have a custom tune?
Why dont you flash to stock and give feedback instead of replacing parts.

The log you posted is not telling me anything. Try post a log in csv format.

 

[Ismail.B]

i have been having some trouble posting the csv file, can i perhaps email it to you?

Yes it is a custom tune.

I have considered flashing the car but would a software related issue cause an intermittent fault? She does run perfectly fine 95% of the time

 

[osiris]

Yes it can. Iv'e had a flash go bad and kept getting strange errors pop up and car doing weird stuff. I rewrote the flash and problem was gone.

But as Twinz said go back to stock, that's something I will always do myself and often recommend others to do when they dealing with a strange issue, Else you end up throwing parts at the car which can end up costing tens of thousands very quickly.

Just like how my hpfp values change drastically due to a tune making the car not run so lekker, I will rather goto stock to see what it does with the cars default fueling tables and torque tables etc. All you need is one value to be typed in wrong by mistake and the car wont be happy.

 

[Ismail.B]

Okay thanks man! Let me flash it back to stock and and see what shes doing