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      09-22-2022, 02:18 PM   #1
Lycoris
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RPM drop and stalling issue on cold start

Hey everyone. I did some searching and I can't seem find a solution anywhere including bimmerpost unless I missed it.

I have a 2016 435i xDrive and I'm not sure if this is an N55 thing.
It's been warm here and for the past two months, if I start the car after having it parked for 8+ hours and immediately (time it takes to put seatbelt on and start my music) shift to reverse or drive, the RPM starts to drop and the engine shuts off. The car then goes to Neutral. No error codes or anything.

If I start the car again immediately after, it drives fine.
Car has NEVER stalled while it's being driven or at red lights.
I can't seem to figure out what's causing this.
It was time to change my transmission fluid so I did that thinking maybe it's trans fluid issue but I'm still getting the same problem.

I don't know if this is a contributing factor but the car has a MHD stage 2+ tune. Maybe a month or two prior to this issue happening, I noticed I stopped getting pops when I throttle after downshifting in sport mode. I just get burbles. It does pop when I drive aggressively. I haven't noticed any loss of power and car appears to be driving the way it always has been. Just not getting any pops that I use to get.

Just to summarize, car stalls if I shift into drive or reverse immediately after starting it when engine is cooled. Weather temperature doesn't seem to be affecting it. No error codes. Car runs fine after if I start it up again.

Any insight would be much appreciated.
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      09-22-2022, 02:57 PM   #2
billnchristy
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Does it do it if you let it go through the "fast idle" stage to where rpm drops below 1000?
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      09-22-2022, 03:03 PM   #3
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The quick fix is to let the car idle for a minute or so before putting it in reverse.
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      09-22-2022, 03:17 PM   #4
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with a warm engine turned off have u disconnected the MAF sensor start car and let idle for 10 minutes ?


https://www.2addicts.com/forums/show....php?t=1932530
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      09-22-2022, 03:30 PM   #5
Lycoris
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Quote:
Originally Posted by billnchristy View Post
Does it do it if you let it go through the "fast idle" stage to where rpm drops below 1000?
It starts below 1000. It only does the warm up when outside temperature is getting cold but during summer it normally sits below 1000 even after cold start. That being said, if I let it run like a minute on idle, it doesn’t have the issue.
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      09-22-2022, 03:47 PM   #6
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Guessing your tune has cold start turned off? Maybe try turning it back on to see what happens?
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      09-22-2022, 03:53 PM   #7
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Quote:
Originally Posted by Caravaggio View Post
with a warm engine turned off have u disconnected the MAF sensor start car and let idle for 10 minutes ?


https://www.2addicts.com/forums/show....php?t=1932530
I just read the thread you linked. I’ll try the MAF fix and see how it goes 😊
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      09-22-2022, 03:58 PM   #8
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FWIW I think my 135i (N55) is in pretty much tip-top shape and does the a similar thing. If I start the car (cold), and put it in reverse, I have to remember to give it just a little extra gas. I haven't had it stall but it does hiccup a bit. I have driven a clutch for like 30 years so maybe I'm just a fraction of a second quicker and can catch it. Similar going forward as well, not just reverse. If the car's warm it's never an issue.
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      09-23-2022, 07:44 PM   #9
Lycoris
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Quote:
Originally Posted by Caravaggio View Post
with a warm engine turned off have u disconnected the MAF sensor start car and let idle for 10 minutes ?


https://www.2addicts.com/forums/show....php?t=1932530
I tried it and it didn’t work :/
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      09-23-2022, 07:46 PM   #10
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Quote:
Originally Posted by billnchristy View Post
Guessing your tune has cold start turned off? Maybe try turning it back on to see what happens?
Previous owner did the tune so I don’t have access to the MHD account
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