[Anwar1995]

Hello guys!

I am almost done doing a major service on my 120k miles 2014 535i and the only issue that I am facing now is rough idle/misfires.

This issue was existing before starting the service and since then I replaced spark plugs and swapped the coils to try pinpoint the cause and it seems like its the injectors as the problem did not move from cylinder 3 and 4 (see attached images of codes).

My only concern by making this post is that how effective is injectors cleaning in solving this issue? I am trying to avoid buying new ones as they are expensive as heck but cleaning costs are relatively manageable.

Plus, is anyone has any feedback of another cause that might be related to these codes? I was suspicous of the ground wire near cylinder 3 and 4 as they are using the same ground wire but it seems fine.

[Hoa]

Could be low or high pressure fuel pump as well. LPFP is 5.2-5.9 bar. HPFP is idle: 50 bar, WOT full load: 200 bar.

[Anwar1995]

Update:

I went and took out injector 3 and 4 to test and clean them. It did not go well; they did not clean good enough and it was obvious at least injector #3 was really bad. At the end of the test, injector 4 put out 60ml while.injector 3 put out 20ml and it was barely even spraying anything. As the codes indicated that both cylinders had the same issue, I did not want to waste money and time trying the cleaned injectors so I bought 2 new Bosch injectors which I will be installing tomorrow.

Fingers crossed that fixes it.

[Hoa]

You have to program them. They are not drop in and go.

[Anwar1995]

@Hoa Yes I am aware of that. Thanks for the headsup.

[Anwar1995]

Update:

I replaced and coded the new injectors. At first it was smooth as butter, idles and revs very well. I drove it back home from the garage and as soon as I reached my neighborhood the CEL came on. I checked it with my scanner and it showed the exact same codes AGAIN! Misfire cylinder 3 and 4 and catalyst damaging exhaust after startup or whatever.

I am baffled to be honest and don't know what to do next. I have eliminated the plugs and coils from the first time and installed new injectors, Now what?

[paul223]

Walnut blast? Check intake valves

[Anwar1995]

Update:

We swapped the plugs again hoping that the problem will move suspecting that maybe the plugs on the old bad injectors location got faulty from all the misfire runs before but nothing changed but after clearing the codes the car drove beautifully and I went for a test drive.

On the drive, when temps hit almost 250F I was almost back at the shop after driving for 10-15 mins and then misfires started coming back very slightly. At that time I realised that the misfires actually don't occur until the engine gets fully warm and temps are at operating temps.

After so, we noticed a whining noise coming from the passenger side of the valve cover. The mechanic suspected that the air/vaccum lines got crunchy and are leaking vaccum because he removed one of the lines while the noise was happening and the noise went away and the car idle changed. It did not become smoother per say but it sort of stuttered then tried to hold the idle better. More so he tried to open the oil cap while the engine was running and it was sucked on stuck, when he took the cap off forcefully the car started stuttring and it died off.

I was on a computer scanner the whole time and looking and the misfire counter page. Before doing anything to the engine, cylinder 4 started counting 1-2 misfires every 2 minutes or so after the test drive and then it goes to 0 automatically. When the mechanic was trying all of the mentioned above the misfire was all over the cylinders.

Order of operation now is to replace those lines, if nothing happened, we will replace the oil cap because we suspects also that the seal is going bad on it. Last thing he suspects is the PCV valve on the valve cover but he thinks its a low chance as it is not whistling or making noise rather the whining noise is coming from the small lines connecting to the passenger side of the VC.

If anyone has any sort of input it would be much appreciated. Thanks for reading through my bad explanation lol!

[Hoa]

Like I said previously, check the fuel pump. There is a high and low pressure. Most likely the high pressure cause this issue.

[Anwar1995]

@Hoa I have already communicated your note to the mechanic. He checked the pressure values of the pumps from the scanner and said they were very good numbers and no worry there. I will verify the values of the pressures next time I go back to the vehicle.

[Anwar1995]

UPDATE!:

After the 2 vacuum lines were replaced, the misfire is gone! Tbh I have not tested the car myself to give it the beans but my brother received the car from the workshop few days ago and did two or 3 drives with it so far and the check did not come up again. according to him the car is smooth as butter and idles very well.

[Anwar1995]

Well, here am I again writing in this thread. The fault came back again with the CEL and the Drivetrain malfunction message in the iDrive. Its basically the same codes:

140010: Misfire, several cylinders: damaging to catalytic converter or damaging exhaust gas
140310: Combustion misfire, cylinder 3: detected
140410: Combustion misfire, cylinder 4: detected
140002: Misfire, several cylinders: damaging exhaust gas after starting up
140302: Misfire, cylinder 3: damaging exhaust gas after starting up
140402: Misfire, cylinder 4: damaging exhaust gas after starting up
140004: Misfire, several cylinders: damaging exhaust gas
140304: Misfire, cylinder 3: damaging exhaust gas
140404: Misfire, cylinder 4: damaging exhaust gas
140001: Misfire, several cylinders: Fuel injection is switched off
140401: Misfire cylinder 4: injection is switched off
140301: Misfire cylinder 3: injection is switched off

Welp, at this point I am quite lost,I installed new BMW plugs and the same issue happens. I swapped coils and plugs, the issue did not move from the cylinders. I installed new injectors in cylinder 3 and 4 and nothing changed.

Any thoughts?

[Anwar1995]

Ok so new day new try. I tried the good ol' removing the MAF sensor to see if it idles better and it actually did idle better (not perfect but better than before). So I learned to understand fuel trims and was monitoring them for some time, took a long drive and came back.

So long fuel trim is at -30% which is too rich and short fuel trim was around -1.8 to -3%. Still rich but I think sorta acceptable.

What I did next is connect the MAF as the car is idling and when I did that the car idled perfectly. And this time I mean it. Short term went to 0 and catalytic converter temps were going down rapidly since the combustion is nearly perfect. I let it idle like that for some time then I thought I would try shut it down and start it again to see what will she do.

When I shut down the car and started it again I got the drivetrain malfuction message immediately and codes of cylinder 3 and 4 decativation codes appeared. Even when that happened the car ran so rich that the catalytic converter temps started rising rapidly.

Will attach screenshots of datastreams when the MAF is DISCONNECTED. Note that I am using metric units.

Any thoughts?

[AlpineweissF10]

Hopefully you figure this out. I'm having the exact same issues with cylinders 3 and 4. Issues arise when engine is operating temps. I'm getting mixture too rich code and misfiring after startup in both cylinders.

So far I have done the following:

1. Walnut blast
2. New spark plugs and coils
3. Replaced broken vent hose which was leaking (could have swore this would fix my issue)

I've done some logging and fuel pressure is solid.

Next up is replacing and coding 2 new injectors. I'll keep you updated once that is done.

[Anwar1995]

AlpineweissF10 Hey man. I really hope that solves your issue.

Just an update from my side. The issue is now way less frequent as I actively try not to shutdown the motor when the engine is warm till I reach my final destination. But currently two things are suspect in my case:

Valve cover as I have no idea if it was replaced or no but it makes a really loud whining noise from the PCV lines that are on the left rear side of it that connect to the boost solinoid (i think). I replaced the lines as I suspected they were old and crunchy but the noise remains so its most likely that the air passages inside the valve cover are gunked up or the PCV is shot. Here is a video that I took and posted it on reddit and most of the comments say its the PCV:

https://www.reddit.com/r/BMW/comment...m_source=share

The second suspect is the Valvetronic motor (eccentric shaft actuator) as it keeps on clicking whenever I unlock/lock the car or even pop or close the hood/trunk. It does not throw any codes at all but I saw online that it is one of the signs that can indicate that its on its way out.

I suspect more of the valve cover than the actuator as the valvetronic motor usually very senstive in throwing codes when it fails so hopefully replacing the valve cover solves it. I know that I can replace the actuator while doing the valve cover as I will already have access to it but to be honest I already spent too much than I expected on this car that I really hope that the valve cover solves the misfire so I can drive it at least without any drivability issues.

[Matgsand]

Either cylinderhead gasket is blown or even worse cracked engine block- common between cylinders 3 and 4 on n55 - leaking coolant into cylinders causing the misfires....if you can drive the car - get the coolant hot and under pressure - pull out spark plugs 3 and 4 and listen for any hissing noises originating from those 2 cylinders, that way you can psychically hear the coolant leaking into the cylinders, or better yet go to an indy shop for a combustion leakage test where they just put the chemical in a syringe over the expansion tank to detect any combustion in the coolant. Good luck.

[Surly73]

Originally Posted by Anwar1995

AlpineweissF10 Hey man. I really hope that solves your issue.

Just an update from my side. The issue is now way less frequent as I actively try not to shutdown the motor when the engine is warm till I reach my final destination. But currently two things are suspect in my case:

Valve cover as I have no idea if it was replaced or no but it makes a really loud whining noise from the PCV lines that are on the left rear side of it that connect to the boost solinoid (i think).

The buzz is almost certainly the boost solenoid itself. I'd order a replacement. Mine used to do that annually until my most recent one. It took 3 years to fail (in the same way) and is just starting to buzz now. Of course my driving patterns have changed starting March 2020 so that's quite likely why they started lasting longer.

[Anwar1995]

Final Update:

So I finally fixed the issue and the short answer to this never ending misfire is the HPFP.

Long answer is that it seems like the ECU whenever is faced with a super rich condition it defaults to shutting down cylinder 3 & 4 which what happened to me. Thankfully it wasn't an issue with those specific cylinders.

What exactly was happening is that the HPFP has a built in valve called the quantity control valve and from my understanding it should regulate the flow coming to the HPFP. In my case that valve seemed to be faulty and it was not regulating the fuel as it should causing the super rich condition followed by cylinder deactivation of cylinder 3 & 4.

This was discovered by a shop that I took my F10 to. They showed me a live reading of the quantity control valve and it was constantly stuck at 0%. I got it replaced by their recommendation and thankfully that was it.

[DaWhole9]

U should thank Hoa. He said it was the HPFP 3 months ago lol. Glad u got it fixed!

[Anwar1995]

DaWhole9 That is correct. Although he mentioned to check the pressure values of the HPFP which were ok in my case but I should have done a thorough check at it.

Hoa Thanks again for your help.