[Diegs14]

Hello everyone. I recently reached 70k miles on my 2014 F30 335i and have began having this issue where every morning I start it and it almost sounds as if it's about to die/stall and the RPM drops to 500 and suddenly tries to save itself from turning off and high revs on its own up to 2K RPMs. This only happens when I first start it (cold start) for the day. Once I allow the engine to warm up, and turn it off, it won't do that again. Nor does it do it throughout the day. Again, only when it's first started for the day. Any suggestions on what I should inspect? Thank you in advance.

(For reference, the vehicle is stock and has no mods, automatic trans, N55 engine.)

https://www.youtube.com/watch?v=vJ46dXtZVyo

[bloodline129]

Mine does the same thing. Haven't figured it out yet. (Mine isn't every day though) but almost daily lol

Changed the plugs and no dice. Injectors got bench tested and no issues. Although I believe that "on occasion" they have a drip that leaves some gas in the chamber and it struggles to burn it off on the first startup in the AM.

Chasing the same issue for few months now as well... let me know if you figure it out

[Tpriest7893]

Originally Posted by bloodline129

Mine does the same thing. Haven't figured it out yet. (Mine isn't every day though) but almost daily lol

Changed the plugs and no dice. Injectors got bench tested and no issues. Although I believe that "on occasion" they have a drip that leaves some gas in the chamber and it struggles to burn it off on the first startup in the AM.

Chasing the same issue for few months now as well... let me know if you figure it out

Did you only change coils? My cold start was a little rough and I changed plugs because they were more then due and it definitely helped my cold start

[bloodline129]

Originally Posted by Tpriest7893

Did you only change coils? My cold start was a little rough and I changed plugs because they were more then due and it definitely helped my cold start

I didn't change coils at all. Just did the plugs.
After doing the plugs, nothing changed. I decided instead of just chasing the gremlin to rather wait until it stalls and get it fixed under warranty (whatever it may be)
But the car is resilient when it comes to stalling.
Playing the wait game as I'm no wiser on the issue.
Originally I managed to log the issue and there was misfires on cylinder 1 and 3 when the issue happened. I only managed to log it once myself so after doing the plugs I was left dumbfounded it's still happening

I have a 435xi at 93k KM

[F32Fleet]

You'll need to pull codes but I'm guessing fuel pressure related. On cold start do you hear the fuel pump prime when you unlock/open door? If not that'll be something to check.

[cfm56d7b]

Originally Posted by F32Fleet

You'll need to pull codes but I'm guessing fuel pressure related. On cold start do you hear the fuel pump prime when you unlock/open door? If not that'll be something to check.

Remote diagnostics are not a perfect science. Scanning for codes first is essential. The symptoms appear to be fuel delivery related: either LPFP (in the gas tank) and/or HPFP.

[bloodline129]

No codes available. Clean as a whistle.

The cold start issue is also sporadic. Maybe 3/4 times a week.

I data logged the cold start with BimmerLink and caught misfires on cylinder 1 and 3 so I replaced the plugs.

Took it to the dealer with the video of the cold start and they tested the coils the injectors and found no issues and absolutely no codes

See attached video I managed to capture

[thejeremyman9]

Did either of you try turning the ignition on first, waiting a few seconds, and then starting the car? Someone on another thread similar to this a while back said that made a difference.

Some people also have reported improvements from running a few bottles of techron complete fuel system cleaner through (one at a time of course, one bottle per tank). This is the same as the BMW cleaner.

[bloodline129]

Originally Posted by thejeremyman9

Did either of you try turning the ignition on first, waiting a few seconds, and then starting the car? Someone on another thread similar to this a while back said that made a difference.

Some people also have reported improvements from running a few bottles of techron complete fuel system cleaner through (one at a time of course, one bottle per tank). This is the same as the BMW cleaner.

I tried the fuel cleaner / wasn't Techron but bought at dealer (can't source Techron in Canada anymore)

I did try the ignition on first few times but honestly I forget more often than not. And since the issue is sporadic I can't make a educated analysis

[thejeremyman9]

Originally Posted by bloodline129

I tried the fuel cleaner / wasn't Techron but bought at dealer (can't source Techron in Canada anymore)

I did try the ignition on first few times but honestly I forget more often than not. And since the issue is sporadic I can't make a educated analysis

You said you logged the issue. Did HPFP pressure drop when the RPM did? That should provide evidence if a fuel supply issue from either LPFP or HPFP.

[bloodline129]

Originally Posted by thejeremyman9

You said you logged the issue. Did HPFP pressure drop when the RPM did? That should provide evidence if a fuel supply issue from either LPFP or HPFP.

Which I knew how to attach the log here. I'm not very mechanically inclined and can't really decipher the logs on my own.

I did send the log to my dealer when they had the car for unrelated issue and they didn't elaborate other than, everything got tested and checked out fine

[bloodline129]

Screenshot attached,

[thejeremyman9]

Originally Posted by bloodline129

Which I knew how to attach the log here. I'm not very mechanically inclined and can't really decipher the logs on my own.

I did send the log to my dealer when they had the car for unrelated issue and they didn't elaborate other than, everything got tested and checked out fine

I need the actual datalog not a SS. Upload the csv of the datalog to datazap then post the link to the uploaded log here. Its free to make an account and that's what everyone uses unless you use BM3's specific platform.

If you want to learn more you can read my thread on datalogging: https://f30.bimmerpost.com/forums/sh....php?t=1732327

[bloodline129]

Originally Posted by thejeremyman9

I need the actual datalog not a SS. Upload the csv of the datalog to datazap then post the link to the uploaded log here. Its free to make an account and that's what everyone uses unless you use BM3's specific platform.

If you want to learn more you can read my thread on datalogging: https://f30.bimmerpost.com/forums/sh....php?t=1732327

I only have bimmerlink to log / car is stock and I don't use any tunes or whatsoever.

Not sure what SS stands for? My bad Jeremy, thank you for taking your time to reply back.

The thing I posted is the only info I am physically able to extract myself

[thejeremyman9]

Originally Posted by bloodline129

I only have bimmerlink to log / car is stock and I don't use any tunes or whatsoever.

Not sure what SS stands for? My bad Jeremy, thank you for taking your time to reply back.

The thing I posted is the only info I am physically able to extract myself

Understood that you are using bimmerlink and the car is stock. SS = screenshot, that you posted above. I can see that you had that in excel (Oct 8.xlsx). I assume bimmerlink saved the datalog in CSV format, or perhaps directly in XLSX as you posted. Either way, you can upload the CSV file directly to datazap, or save the XLSX as CSV then upload the CSV (excel has this option). It looks like the SS you posted was from your phone; you should be able to do all of this from your phone or copy the file to your computer if needed.

If none of that works just upload the actual datalog as an attachment here.

Upload here, then post link to the specific log.
https://datazap.me/

[bloodline129]

Originally Posted by thejeremyman9

Understood that you are using bimmerlink and the car is stock. SS = screenshot, that you posted above. I can see that you had that in excel (Oct 8.xlsx). I assume bimmerlink saved the datalog in CSV format, or perhaps directly in XLSX as you posted. Either way, you can upload the CSV file directly to datazap, or save the XLSX as CSV then upload the CSV (excel has this option). It looks like the SS you posted was from your phone; you should be able to do all of this from your phone or copy the file to your computer if needed.

If none of that works just upload the actual datalog as an attachment here.

Upload here, then post link to the specific log.
https://datazap.me/

https://datazap.me/u/bloodline129gma...og=0&data=

Like this?

This was just 30 seconds log in cold start

[thejeremyman9]

Originally Posted by bloodline129

https://datazap.me/u/bloodline129gma...le?log=0&data=

Like this?

This was just 30 seconds log in cold start

Well, rpm isnt even on there but it looks like you dont have any unexpected rail pressure dip.

[bloodline129]

Originally Posted by thejeremyman9

Well, rpm isnt even on there but it looks like you dont have any unexpected rail pressure dip.

I'll add the rpm to the list of things it should log and hopefully catch it again.

Thank you for all your input Jer. Appreciated

[SC435i]

This might be unrelated but I had a similar issue except that the rpm dip was more aggressive. When I scanned the car with Bootmod3 it didn't pick up any codes, but bringing it to my mechanic they found that my battery was on its last leg and the Valvetronic servomotor was busted.

I doubt it's your servomotor so I would check your battery to see what the voltage is, and if it's low switching it out might solve your problem.

[thejeremyman9]

Originally Posted by SC435i

This might be unrelated but I had a similar issue except that the rpm dip was more aggressive. When I scanned the car with Bootmod3 it didn't pick up any codes, but bringing it to my mechanic they found that my battery was on its last leg and the Valvetronic servomotor was busted.

I doubt it's your servomotor so I would check your battery to see what the voltage is, and if it's low switching it out might solve your problem.

I was thinking battery voltage could be a factor, but his sits over 12 and only drops to 11s when cranking it seems.

Nonetheless could be worth fully charging the battery before cold starts and see if the problem goes away.

[bloodline129]

I've been debating changing the battery but according to BimmerLink it sits at around 70% charge. And that seems to be average.

I did charge it fully few months back but I never thought of that to be related to the rpm dips.

The battery is OG so 5+ years

The rpm dip didn't happen this morning but after work it did it again. I forgot to log it this time ughhhh.

[Diegs14]

Originally Posted by bloodline129

Mine does the same thing. Haven't figured it out yet. (Mine isn't every day though) but almost daily lol

Changed the plugs and no dice. Injectors got bench tested and no issues. Although I believe that "on occasion" they have a drip that leaves some gas in the chamber and it struggles to burn it off on the first startup in the AM.

Chasing the same issue for few months now as well... let me know if you figure it out

Thanks for your input. I'll keep trying to identify the issue and post it here if I find something.