[atek]

Originally Posted by RichardC300

My car did this and still does occasionally. The MAF fix works every time I do it. But it usually comes back after significant changes in temperature day-to-day, and sometimes, I won't bother doing the reset and it'll go away and come back as it pleases. I wonder if a new MAF sensor will permanently resolve it, but I don't think I'll spend the money to find out.

Intermittent operation that changes with ambient temperature usually points towards faulty/shorted electrical wiring or failing electrical sensor [extreme cases point to fuel delivery system]. I'd bet swapping it out with a new one would fix the issue. Check voltages/resistance of the MAF and compare with what it should be from OEM. MAF's usually read very low resistance (OHMS) when good.

[MegaMatt3]

Originally Posted by RichardC300

My car did this and still does occasionally. The MAF fix works every time I do it. But it usually comes back after significant changes in temperature day-to-day, and sometimes, I won't bother doing the reset and it'll go away and come back as it pleases. I wonder if a new MAF sensor will permanently resolve it, but I don't think I'll spend the money to find out.

Do you have a stock charge pipe? And if so, have you ever had anyone check to make sure it's properly sealed on both ends? I could go days without feeling a throttle problem, and other days it was extremely apparent. If you're having even intermittent problems, I'd check for boost leaks in your charge pipe, as it turns out that was my problem for many years. Wish I'd done it sooner.

[jackelliott]

Mine did this for a couple years. It was the charge pipe. Replaced it and now it starts perfectly and strong every time. Must have been a tiny leak of some kind.

[rtl32]

Mine used to do this. Tried cleaning the MAF, resetting it, replacing it, plugs/coils, fuel quality, different intakes, nothing fixed it until I replaced all of my injectors after the first few hundred miles on ethanol. Every start since has been perfect and it cleaned up some hiccups and stumbling in the low end that I didn't even know were there until they I noticed how smooth and powerful the car was with the new injectors.

[RichardC300]

Originally Posted by atek

Intermittent operation that changes with ambient temperature usually points towards faulty/shorted electrical wiring or failing electrical sensor [extreme cases point to fuel delivery system]. I'd bet swapping it out with a new one would fix the issue. Check voltages/resistance of the MAF and compare with what it should be from OEM. MAF's usually read very low resistance (OHMS) when good.

I'll keep that in mind! I reset it again shortly after your reply, and it's been good since through various temps and altitudes. I just have to reset it a few more times per year than others here, it seems.

Also, are these OEM specs for voltages/resistance available to the public somewhere?

Originally Posted by MegaMatt3

Do you have a stock charge pipe? And if so, have you ever had anyone check to make sure it's properly sealed on both ends? I could go days without feeling a throttle problem, and other days it was extremely apparent. If you're having even intermittent problems, I'd check for boost leaks in your charge pipe, as it turns out that was my problem for many years. Wish I'd done it sooner.

I do have an aftermarket charge pipe, but I don't think that is an issue at the moment. A while back, I had my car smoke tested to narrow down a tiny leak in the intake tube that was throwing a code, and the charge pipe was fine. My throttle feels pretty consistent to me. Good tip, though! I've seen many post about charge pipe leaks.

[CO_Steve]

I found this thread because I was having the same issue. I had bought a replacement metal charge pipe but hadn't installed it. I have a lift but it was going away next week so I did the swap yesterday. Sweaty job in 108 degree heat. The problem is gone. I cannot see any issues with the oem part. No cracks, still flexible. I wonder if they shrink enough to cause leaks at the end connectors? Anyway, all good now.

[RichardC300]

I had a shop diagnose this issue, since it kept returning more frequently than some of the other people here. They updated software (no confirmation on if there was an actual difference in firmware version) and reset the DME. No issues since. Several overnight cold starts in temps ranging from 60s to 80s. Hopefully, my issue is resolved long-term.

[ggggbmw]

Originally Posted by RichardC300

Several overnight cold starts in temps ranging from 60s to 80s. Hopefully, my issue is resolved long-term.

Sorry, as we head into the short days, and sub-freezing temperatures, I was amused by the idea of 60 being a 'cold start'.

[MLJR235]

Originally Posted by ggggbmw

Sorry, as we head into the short days, and sub-freezing temperatures, I was amused by the idea of 60 being a 'cold start'.

Lmfao... as a Cali native, I can relate to 60's "cold" temps God forbid it hits sub 50s .. That's when the snow jackets, mittens, ear muffs, and scarfs come out hahahaha.

[YYZF22N55]

Originally Posted by pmcmtnbkr

2015 M235i with 54k miles this just started a few weeks ago and only on overnight cold starts. I found some old threads from 2014 but no real resolution. Symptom only occurs on the very first start of the day. The car will start Rpms around 1200 to 1500 they will start to drop with a noticeable stumble sounds and feels like the engine is going to stall then the rpms pick back up. There are no codes of any kind being generated, the car runs completely normal no power loss or ruff idle after the first stumble. I am at a bit of a loss as to what it could be since anything I try will have to wait until the next morning to verify if it worked, spark plugs were done last year at the 40k mark no issues since then. I did clean the MAF sensor just as a starting point no change. Anyone have an issue like this that they where able to solve

Sounds like your fuel injectors could be dirty. Have you tried using fuel injector cleaner?

[pmcmtnbkr]

Originally Posted by YYZF22N55

Sounds like your fuel injectors could be dirty. Have you tried using fuel injector cleaner?

its not dirty injectors the problem resolved with resetting the Mass air flow sensor, and hasn't returned

[Slopoke133]

Hi all. New member here. My 2015 has done this off and on almost since I bought it new. I would like to try the fix. But I am not too mechanical, and could use advice on how to remove the plug. It looks like there is a little latch but I could not get it off easily and didn’t want to force it.

Thanks!

[Slopoke133]

My car has done this off and on almost since new. Dealer could never figure it out. I tried the MAF sensor disconnect as described above and….. it worked! Thanks

[LA1Z24]

Leaking fuel injector is pooling fuel on top of the piston overnight. Start it up, oxygen sensor sees giant rich condition as the raw fuel enters the exhaust, then the DME goes full lean to compensate for the rich condition. Idle then stabilizes.

Shut car off, and go inside for the night. Come out in the morning. Hook up bi-directional scan tool. Key on, DO NOT START THE ENGINE. Look for the fuel rail pressure pid. If it says anything under say 550psi, an injector is leaking. The fuel system MUST NOT leak down overnight. If the rail pressure drops, an injector is leaking. If the low pressure fuel system pressure drops, the check valve in the fuel pump module is bad.

[seanroberts000]

Not to hijack thread, but anyone know if this MAF reset would also work for the B58?