Cold start stalling, 35i

[mfinn]

Originally Posted by firstbimmer

I had exact same issue for almost a year...engine would stall out and die on various cold starts. Worst was when i was skiing and car would barely start or stay on. For a while the dealer said no problem, then i left it for days so they could reproduce the issue. Once they acknowledged the issue, dealer said software would fix problem, which sounded silly to me. But they did a software update and I've had zero issues and no stalling in about 8 months since.

I have extended warranty so they could have fixed anything and it would have been covered, so they had no incentive to not fix something if broken. I assumed I'd be back when the cold start idle shut down occurred again, but here i am, many months later and issue is gone. Ive been skiing a bunch since December and not one issue in the cold this winter.

Unfortunately I still have this issue after updating to the most current software in my 2015 35i (112k miles). Anybody have any clue what else it could be?

[F15_SGM]

Originally Posted by mfinn

Unfortunately I still have this issue after updating to the most current software in my 2015 35i (112k miles). Anybody have any clue what else it could be?

Its your vacuum hose or PCV hose thats connected on your valve cover and air-box duct. If any spark plug work has been done those are removed to replace plugs. So check those because when i replaced my plugs i stopped half way just loosely connected it and it stalled in cold weather in reverse. One of those hoses are either loose or cracked as it is brittle. If that doesn't fix it maybe it an injector issue. you can try some chevron techron cleaner to test if it makes it better.

[lht5059]

Originally Posted by osmansiddiqui95

Its your vacuum hose or PCV hose thats connected on your valve cover and air-box duct. If any spark plug work has been done those are removed to replace plugs. So check those because when i replaced my plugs i stopped half way just loosely connected it and it stalled in cold weather in reverse. One of those hoses are either loose or cracked as it is brittle. If that doesn't fix it maybe it an injector issue. you can try some chevron techron cleaner to test if it makes it better.

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This. This is exactly what I wanted to comment on but refrained from doing so since I don't have experience with the 35i...

I've recently replaced one of the vent pipes since one of them cracked, on my 50i and cold start no longer experiences any cold start RPM fluctuation. The ones that came with my 2015 were the old, brittle hard plastic ones, while the new one is the upgraded thick rubber ones... Check if you have an oil leak/burnt around/on these pipes; I would replace them regardless if there is any.

[tlow98]

I am posting this here for anyone that finds it. I solved my cold start stumble very easily.

2014 XDrive 35i

I unplugged the MAF on a cold engine and gave it one complete warm-up and drive cycle with the MAF unplugged (it ran fine and no check engine light came on). Then I plugged the MAF back in and allowed the motor to go back to completely cold before turning it on again.

The issue has not returned for 1 month of daily starts. Previously, it was stumbling and running rough on every single cold start for 5 months. I was dreading the injector replacement or taking it back to the dealer for coding. Neither was necessary.

I can't explain it, but I saw it posted a couple of other places and it also worked for me. I'm assuming it resets some adaptions.

Anyway, hope this helps someone!

[dr_greenthumb]

Originally Posted by tlow98

I am posting this here for anyone that finds it. I solved my cold start stumble very easily.

2014 XDrive 35i

I unplugged the MAF on a cold engine and gave it one complete warm-up and drive cycle with the MAF unplugged (it ran fine and no check engine light came on). Then I plugged the MAF back in and allowed the motor to go back to completely cold before turning it on again.

The issue has not returned for 1 month of daily starts. Previously, it was stumbling and running rough on every single cold start for 5 months. I was dreading the injector replacement or taking it back to the dealer for coding. Neither was necessary.

I can't explain it, but I saw it posted a couple of other places and it also worked for me. I'm assuming it resets some adaptions.

Anyway, hope this helps someone!

I am going to try this, I kicked your information around thinking to myself that this isn't some electrical gremlin, or a problem just won't go away. I came back to this thread again, re-reading it, and it occurred to me that you you have been around this forum and BMW, so you may have some street cred, so I will give it a shot. Been fighting this booger for a while now....

[tlow98]

Originally Posted by dr_greenthumb

I am going to try this, I kicked your information around thinking to myself that this isn't some electrical gremlin, or a problem just won't go away. I came back to this thread again, re-reading it, and it occurred to me that you you have been around this forum and BMW, so you may have some street cred, so I will give it a shot. Been fighting this booger for a while now....

15 years of BMW diy on ~6 cars. Currently rebuilding an entire motor, but that’s another story. The only reason I didn’t try this sooner was I thought it sounded ridiculous, despite the fact that others posted it working for them. I figured I had nothing to lose as it take 2 minutes to unplug the MAF. (Use a pick in the lock side with a mirror… will make it easier. It slides off the MAF toward the passenger side). Take it slow and easy on the MAF clip. You’ll get it. When the plastic lock pops it comes right off easily. You could also easily remove the plastic cladding to give you all the access in the world in just a couple of extra minutes.

What frustrates me is I can’t explain why it worked. If it were an adaptions thing I’m assuming you could reset the adaptions via a code reader, but I didn’t try that either. I just figured it must be a hardware issue all Along, so I didn’t try this… until recently.

Other non hardware fixes have been successful going through the dealer with what people were reporting as a “software update”. Now, what that entails is anyone’s guess… they could be updating the software or they could be resetting adaptions or (laughably) unplugging the MAF.

All I know is it worked. And I feel like a fool for not doing it sooner. That’s why I spammed like 5 threads including my build thread. Hope this helps you too!

Obviously, if there’s an actual hardware issue my suggestion won’t help, but judging the amount of ppl that were able to solve this with a dealer “software update” I’m assuming unplugging the MAF will help a good % of owners. It’s also free and easy.

[doru]

If it's a turbo engine, then there is no MAF.
If it's a turbo angina and a MAF, I would really like to see a pic of it. Because turbo engines have no MAF, AFAIK.

[jkwhar]

Originally Posted by doru

If it's a turbo engine, then there is no MAF.
If it's a turbo angina and a MAF, I would really like to see a pic of it. Because turbo engines have no MAF, AFAIK.

#2

https://www.realoem.com/bmw/enUS/sho...diagId=13_1357

[tlow98]

Originally Posted by doru

If it's a turbo engine, then there is no MAF.
If it's a turbo angina and a MAF, I would really like to see a pic of it. Because turbo engines have no MAF, AFAIK.

Yeah see next post for correct answer.

If anyone finds this in the future try unplugging part #2 linked above.

[Rrswartz@gmail.com]

I tried unplugging the connector. After hooking it back up, the check engine symbol came up. This video shows how to reset the check engine light. As a bonus, you can also do a software update. Is this the same software update a dealer would do? I did that was well, so if it is now cured, I will not know for sure which one fixed it.
You can also reset many indicators such as oil changed, new brakes, etc.

[tlow98]

You can’t do a software update without new software being plugged in and uploaded. It could be a reset to the adaptions however.

[sukhk527]

If unplugging and re-plugging the MAF + code clearing worked , is that not indicative of a prematurely failing MAF? Similarly, resetting adaptions could provide a solution if the hardware is good.

[tlow98]

Originally Posted by sukhk527

If unplugging and re-plugging the MAF + code clearing worked , is that not indicative of a prematurely failing MAF? Similarly, resetting adaptions could provide a solution if the hardware is good.

Maybe, but it hasn’t returned in 1 year +. I thinks it’s a glitch for lack of a better term. You could try resetting the adaptions. That hasn’t proven to be successful for anyone this far, however.

[sukhk527]

Fair enough, I stand corrected.

[tlow98]

Originally Posted by sukhk527

Fair enough, I stand corrected.

No worries, we’re all in this together. I love the ideation and suggestions. This is how we solve the problems :-)

This one was incredibly confusing for me, but in the end I’m just so incredibly happy it worked out.