stalls on first start, then starts up fine

8900120d

Lurker
Apr 5, 2018
22
1
0
Ride
335i
The coils and plugs are new, I’m not sure about the injectors, they seem fine when the maf is disconnected.

I’m not getting any codes via inpa.

I may bite the bullet and order a new maf
 

silverstreak18

Corporal
Jan 3, 2018
129
67
0
Charlotte, NC
Ride
2016 M3
Do you have a buddy with the same motor? Or ask on the forums if anyone is close and will just meet up and swap mafs quick to be sure thats the issue.
 

8900120d

Lurker
Apr 5, 2018
22
1
0
Ride
335i
Do you have a buddy with the same motor? Or ask on the forums if anyone is close and will just meet up and swap mafs quick to be sure thats the issue.

Not many people around here with an e9x n55, i think the newer n55 motors have a different MAF.
ive ordered a new MAF which will hopefully fix the issue, also ordered new gaskets for the inlet pipes.
will keep you guys posted
 

Velocity26

Specialist
Feb 7, 2017
61
21
0
Tampa, FL
Ride
2010 335i
Mine did the exact same thing as the HPFP was starting to go. Within a short period of time, it got progressively worse until it was obvious, with progressively longer cranks, etc. The car should reach and hold 1000+ psi of fuel pressure instantly after start-up and maintain it constantly. If the pressure immediately drops, it is because it is not priming and holding the fuel pressure. For whatever reason, the pressure would always come up on the second crank and it would hold the pressure until the next cold start. Initially, this was only a problem on the first start of the morning, then got worse. The car will initially start on the ~75 psi of the LPFP, but that will only allow it to run rough and stall.
 

8900120d

Lurker
Apr 5, 2018
22
1
0
Ride
335i
Mine did the exact same thing as the HPFP was starting to go. Within a short period of time, it got progressively worse until it was obvious, with progressively longer cranks, etc. The car should reach and hold 1000+ psi of fuel pressure instantly after start-up and maintain it constantly. If the pressure immediately drops, it is because it is not priming and holding the fuel pressure. For whatever reason, the pressure would always come up on the second crank and it would hold the pressure until the next cold start. Initially, this was only a problem on the first start of the morning, then got worse. The car will initially start on the ~75 psi of the LPFP, but that will only allow it to run rough and stall.

But with my issue, on the second start-up it starts and runs fine. according to the logs, on the first start-up it reached 1000+ psi at only 500rpm before it stalled, it was at 1500+ psi before it stalled.
and the weirdest thing is that it runs perfectly fine when the MAF is disconnected.
 

ganque

Specialist
Jan 22, 2018
60
15
0
Ride
BMW 135i N55 DCT pure stage 2
I'm having the exact same issue, but I have to crank it up like 4 times in order to get a normal start-up/idle.
I haven't tried disconnecting the MAF, but I think in my case is due to Ethanol content in my tank. Currently running E50.
I saw a video on YouTube that you can try to reset adaptions for Valvetronic. Here's the vid

Thanks!
 

Alturiak

Specialist
Jan 12, 2019
61
54
0
Ride
2011 335i E92
What was the solution to this? My built N55 does this now since getting built and I'd like to fix it... How do you test for a bad injector?
 

Alturiak

Specialist
Jan 12, 2019
61
54
0
Ride
2011 335i E92
What was the solution to this? My built N55 does this now since getting built and I'd like to fix it... How do you test for a bad injector?
Just wanted to post some sort of update to follow up on this. I took the entire car back to stock and slowly started adding piece by piece my aftermarket parts to see if one in particular was the problem causing the stalling. Ultimately my findings are that something is not right with the @mhd "cold start noise reduction" option when it is checked/turned on.

I found that if it was after a fresh flash with that option, the car would cold start no problem. All I did was cold start it for about a week, twice a day (once in the morning and once at night) and it started up perfect every time nice and quiet and the RPMs immediately sitting at 650-700. I logged every start to hopefully catch something. I never drove it during this week- only cold starts. Then I found that after driving for the very first time and the car getting warmed up during that time (ie obd readiness monitors switching to "ready") that the very next cold start the stalling issue returned like it never left. Upon a fresh flash I was able to repeat the perfect cold starts for another week, and then again right after driving it to warmed up state the problem was back again. I also logged the cold starts with the noise turned on (ie the option turned off) to try and compare the logs with the others when it started perfect and stalled out and I could not find anything that would point to a "smoking gun" of sorts as the cause.

My "solution" has been to simply turn the option off and have cold start noise since the car starts up perfect that way, but it would be really nice to be able to turn the noise off and not have any issues from it.
 
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