[nike001]

Originally Posted by aerostar

That's pretty normal for a car to not want to start moving right after you start the car...

My WRX used to do the same. The computer is telling the engine to keep the idle RPM a little higher as the engine's cold and you're killing its mojo by connecting the transmission lowering the RPM to choke it out

This. The car is idling higher to get everything warmed up and you're interrupting it by putting it in reverse and placing load on the engine. Let the thing warm up for a few seconds!

Usually when I'm getting into my car I start it, then put my seatbelt on and hook up my phone and by the time I choose a song I'm ready to go

[DanG]

Originally Posted by nike001

This. The car is idling higher to get everything warmed up and you're interrupting it by putting it in reverse and placing load on the engine. Let the thing warm up for a few seconds!

Usually when I'm getting into my car I start it, then put my seatbelt on and hook up my phone and by the time I choose a song I'm ready to go

Actually it is not normal. Your local BMW technician will tell you the computer system should adjust the fuel for it to not stumble or stall.

Mine was doing this and the dealer wanted me to bring it in for service. I ended up with a new fuel pump and a software upgrade. It hasn't stumbled or stalled since.

[nike001]

Originally Posted by DanG

Actually it is not normal. Your local BMW technician will tell you the computer system should adjust the fuel for it to not stumble or stall.

Mine was doing this and the dealer wanted me to bring it in for service. I ended up with a new fuel pump and a software upgrade. It hasn't stumbled or stalled since.

I didn't say it was normal. I was saying that you should let the car gather itself for a few seconds on a cold start before you place a load on it. If your issue isn't a fuel pump, chances are that by doing that... you'll have mostly eliminated your issue

[RedRocketM2]

My car did it again yesterday on a cold start up, as expected the claim of the cause being contaminated oil is laughable.
Its booked to go in next week, lets see what else they claim the issue is before doing the fuel pump....

[Black2]

Bump any updates?

[QuinnM]

Originally Posted by Black2

Bump any updates?

It seems the idea at the time this thread was posted is that it was a fuel pump issue.

My car does this almost every morning for cold starts in varying severity regardless of fuel or ambient temperature.

I have taken my car to my nearby BMW dealer three separate times for them to look at the car but each time they said they could not replicate the issue even though I sent them these videos and the first time they held my car for almost a week.

It is not bad fuel and not ambient temperature.

Three examples of what my car does nearly every morning during cold start.

[bimmerfile]

Originally Posted by QuinnM

.................................................. .................................................. .................................................. .................................................. .............................

Three examples of what my car does nearly every morning during cold start.

Thanks for posting those videos.
That's exactly what was happening to my (former) 2016 M235xi ragtop, except mine would only do that about 1 out of every 3- 4 cold starts and it only ever occurred during the initial start-up of the day.
My M235xi was always parked overnight 2 levels down (Condo), so the temp there was never to warm or too cold - and temp didn't seem to have any impact on whether or not the RPMs would take a dip during the initial start-up.
It never bothered me (or the car apparently), but it was a curiosity.
I don't recall it doing that during the 1st year of ownership.
It would be interesting to find out if it is an issue which needs to be addressed as my "old" 2016 M235xi is now my son's car - and if it is an issue to be addressed he'll need to do so before the 4 year warranty expires Nov 2019..

[aozer]

my car used to do this on every startup, with it being more severe in cold weather.

for some reason it went away on its own and has done it in more than 6 months now. only changes are new oil and new charge pipe, not sure why it went away.

[XutvJet]

Originally Posted by QuinnM

It seems the idea at the time this thread was posted is that it was a fuel pump issue.

My car does this almost every morning for cold starts in varying severity regardless of fuel or ambient temperature.

I have taken my car to my nearby BMW dealer three separate times for them to look at the car but each time they said they could not replicate the issue even though I sent them these videos and the first time they held my car for almost a week.

It is not bad fuel and not ambient temperature.

Three examples of what my car does nearly every morning during cold start.

So my 2016 M235 6mt with 50k miles just started doing this about 4 days ago. Does this on every stone cold start now. No codes. Runs perfectly otherwise. Same 93 octane fuel as always, spark plugs (OEM replacements) were changed about 7k miles ago, new OEM air filter, and no changes in mods in over a year. No vacuum or charge pipe leaks.

Anyone ever figure this out?

[Heitzer]

Perhaps it has to do with the switch to summer fuel? Some states require different formulations (higher oxygenated fuels) and Missouri is one of them I think. Usually kicks in beginning of April.

Do you still use the Dynantronics sport tuner? I recall my start ups to be a lot more uneven when using the tuner compared to stock or my current BM3 flash.

Just some thoughts.

[XutvJet]

Originally Posted by Heitzer

Perhaps it has to do with the switch to summer fuel? Some states require different formulations (higher oxygenated fuels) and Missouri is one of them I think. Usually kicks in beginning of April.

Do you still use the Dynantronics sport tuner? I recall my start ups to be a lot more uneven when using the tuner compared to stock or my current BM3 flash.

Just some thoughts.

I run the Dinantronics Stage II piggyback and have been running that for over a year without issue.

I do agree, this may be a fuel quality related issue. As you noted, the change to "summer" gas occurred in Kansas in late April. The issue developed in early May. It's possible that the DME in my M235 was not fully agreeable with the summer gas from the BP I routinely visit. This has never happened before so perhaps BP is using a new additive?

Either way, the issue seems to be not as severe. The last two cold starts were not as aggressive with wanting to almost stall. I also filled up with new gas three days ago (same store). Maybe I just got bad gas? I was out driving today and the car was a bit more punchy and lighting them up from a 2nd gear roll at 40mph. That caught be off guard a bit.

[Heitzer]

Yes, bad gas is the likely culprit. It can be just one particular tank at a gas station that has gunk in it, wasn't cleaned in a long time or not cleaned properly.

I try to use well frequented gas station. They will likely get gas deliveries more often.

I had to buy Premium in a rural state once and experienced limp mode on that tank of gas. I can't prove it was the gas and that particular station but our engines are in pretty advanced state of tuning particular with mods - can't be careful enough.

[XutvJet]

Update and fix for me:

Cliff Notes:

If you have a 2014+ N55 6MT that has a near stall cold start issue try this: On a warm engine that's off, disconnect the MAF sensor, and restart the car. Let it run at idle for a few minutes. Then shut the engine off. Reconnect the MAF sensor and see if it remedied the issue on the next cold start.



After a bit more research on this forum and the F-series 3/4 series forum, it appears that this particular issue of nearly stalling on a stone cold start tends to effect N55 6MT cars that have the MPPK tune. That would mean the M235 (comes with the MPPK tune as stock) and the 335/435 cars that have added MPPK tune. This issue appears to be more prevalent in cars with aftermarket air filters.

This cold start nearly stall issue popped up in my 2016 M235 very shortly after I swapped my AFe air filter back to the OEM air filter. I had the AFe filter in for about a week before swapping back to the OEM air filter. I've also been running the M2/MPPK airbox for over a year.

My spark plugs are OEM and were replaced within the past year.

The issue didn't remedy itself with gas from a different station.

I had not CELs or ghost codes.

The car drove fine otherwise, including hot restarts.

I have the OEM battery which I put on a tender once or twice a month. The battery checks out completely fine.

There are no vacuum leaks.

I'm not one to throw parts at a fix and it didn't make much sense to me that something was broken or going out given that this issue only occurs for about 1 second on a cold start. I knew BMW would be of no help as there aren't codes and seeing from what others went through with BMW, I wasn't going to let them throw parts at the car in hope of fixing the issue.

Someone in this thread said they thought it may be a learned tuning glitch. They pulled the MAF sensor a few times and ran the car that way and they said the issue cleared up. I figured, what the heck?

So 5 days ago I did the following: on an off warm engine, I disconnected the MAF sensor and started the car. I also removed the four most easily accessible coil packs and inspected them. I saw no issues with them. I reinstalled them on different plugs though just for the heck of it. I then started the car and let it run for 10 minutes. No CEL light turned on (I didn't check for ghost codes). I then shut the motor off. 18 hours later, I restarted the car and it started perfectly. No hiccups what so ever. It's been that why for the last 4 days.

I'm pretty certain it was a learned tuning glitch with the DME, possibly with me swapping the air filters. I'm not sure why this would cause an issue as I've swapped between the AFe filter and OEM filter numerous times over the past 4 years. Yanking the MAF somehow remedied it. I doubt swapping the coil packs around did anything, but it's worth doing at the same time because it takes 5 minutes to do.

[johnogorman512]

@ XutvJet - When you say "disconnect the MAF sensor", do you mean unplug the MAF sensor from its ECU connector, or do you mean leave the MAF plugged into the ECU and unscrew the MAF from the airbox?

Thanks!
John

[XutvJet]

Originally Posted by johnogorman512

@ XutvJet - When you say "disconnect the MAF sensor", do you mean unplug the MAF sensor from its ECU connector, or do you mean leave the MAF plugged into the ECU and unscrew the MAF from the airbox?

Thanks!
John

Unplug the MAF electrical connector from the MAF sensor. Removing the sensor from the MAF body would create a massive vacuum leak and make it run terribly.

[Skowron]

I get exactly same issue on my 2014 435i like on movies in @QuinnM post. Anyone found working solution for that?

[XutvJet]

Read what I posted.. Simple as that.

[johnogorman512]

Wow, XutvJet is absolutely right. Maybe too early to call it, but I did as XutvJet said a week ago and have had nothing but clean cold starts since. Thanks!

[Jmoney2055]

XutJet do you leave the MAF unplugged for 18 hours and then before you stRt it up you plug the MAF back in? Or just let it run for 10 minutes without it plugged in and then plug it back in for 18 hours? Thanks and hope you can see this still!

[celsdogg]

Originally Posted by Jmoney2055

XutJet do you leave the MAF unplugged for 18 hours and then before you stRt it up you plug the MAF back in? Or just let it run for 10 minutes without it plugged in and then plug it back in for 18 hours? Thanks and hope you can see this still!

The 18 hours is meaningless, he just means the next cold start it'll be better. Just unplug the MAF and let it sit idling for 10 minutes. Shut it off and plug it back in then go back to normal usage.

This causes the DME to fallback to Alpha-N mode. It is pretty much a predetermined air/fuel table that is used in the event some sensor isn't working, like an unplugged MAF.

FWIW, I have 2 N55's a F30 335i and M235i. Neither have any performance mods and both exhibit this behavior from time to time. I stopped unplugging the MAF and worrying about it as it isnt consistent and doesn't really seem to harm anything other than my ego in a crowded parking lot. At this point, I just consider it part of the character of the car.

[Jmoney2055]

Okay thanks a lot, I do have performance mods on my car so I will try that and then see what happens. Hoping it works bro, thanks a lot for replying!

[Udayan]

Hi,

Happy new year.

I experienced the same issue last month on a cold morning with my F23 M240i.

I have not been driving the car for about 1 month and the battery was not fully charged.

Then, I took the car for a spirited driving session in order to recharge the battery. After that, the car has been fine.

The car is remapped (E85/stage 1), spark plugs are brand new.

From my experience, low battery could be one of the potential cause of the problem.


Udayan