BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read
M2 Technical Topics > N55 Engine / Drivetrain / Exhaust / Bolt-ons / Tuning > Cold start rpm drop

Post Reply
 
Thread Tools Search this Thread
      08-14-2018, 09:55 AM   #1
bmwizgoat
Private
11
Rep
86
Posts

Drives: 2017 sti
Join Date: Dec 2017
Location: Canada

iTrader: (0)

Cold start rpm drop

Soon after I started my car, the rpms dropped more then usually. I thought it was gonna stall but they climbed back up quickly. Has this ever happened to anyone else ? Is it a problem?
Appreciate 0
      08-14-2018, 10:02 AM   #2
Lukeni
Private First Class
68
Rep
175
Posts

Drives: BMW M2
Join Date: Jun 2017
Location: Switzerland

iTrader: (0)

Quote:
Originally Posted by bmwizgoat View Post
Soon after I started my car, the rpms dropped more then usually. I thought it was gonna stall but they climbed back up quickly. Has this ever happened to anyone else ? Is it a problem?
Me and some other m2 drivers had this issue this summer driving in the dolomites in italy. I guess it was bad gas. Engine almost stalled.
Appreciate 0
      09-25-2019, 11:27 AM   #3
TheAMackAttack
Private First Class
United_States
47
Rep
104
Posts

Drives: 2016 M2 LBB DCT
Join Date: Aug 2018
Location: Salt Lake City

iTrader: (0)

Yea my car is having a similar issue that I haven't noticed before. On cold start, RPMs start at ~1000, drop down to 500-600 for a second and the engine sounds like it's almost going to stall, and then it shoots up to 2000 real quick. I presume the latter part is normal for the cold start mechanism but the 500-600 bit seems weird.

I just moved to Colorado where the highest rated gas I can find is 91, but that alone wouldn't be bad enough to cause this, right? Can anyone comment on what the cold start mechanism normally is and if mine is indeed abnormal?
Appreciate 0
      09-25-2019, 08:41 PM   #4
Mosely
Lieutenant
Mosely's Avatar
593
Rep
450
Posts

Drives: '18 M2 | '20 X5 | '07 E92
Join Date: Mar 2017
Location: SoCal

iTrader: (1)

Quote:
Originally Posted by TheAMackAttack View Post
Yea my car is having a similar issue that I haven't noticed before. On cold start, RPMs start at ~1000, drop down to 500-600 for a second and the engine sounds like it's almost going to stall, and then it shoots up to 2000 real quick. I presume the latter part is normal for the cold start mechanism but the 500-600 bit seems weird.

I just moved to Colorado where the highest rated gas I can find is 91, but that alone wouldn't be bad enough to cause this, right? Can anyone comment on what the cold start mechanism normally is and if mine is indeed abnormal?
That is not a typical cold start. Should idle around 1500-2000 depending on temp immediately after starting and then after about 15-20 seconds, drops to around 1200-1500 and then about 30-60 seconds later it settles lower.
__________________
IG Photo Gallery:
instagram.com/dr_m2sko/

Appreciate 0
      09-26-2019, 04:03 PM   #5
nismoman
Private
40
Rep
78
Posts

Drives: 2017 LBBM2,2001 LSB M3,S52 E30
Join Date: Dec 2012
Location: Huntersville, NC

iTrader: (0)

Same here only sometimes, I always run 93 and octane booster. so gas is not the issue for me, I do have a bm3 tune, intake, ic, catless dp. Again, it never stalls and only sometimes does the weird cold start. I have not really worried about it as it clears up within seconds and i assume it is just related to the tune .
Appreciate 0
      04-16-2023, 01:30 AM   #6
mikeyryap
Private
mikeyryap's Avatar
9
Rep
78
Posts

Drives: F87 M2
Join Date: Feb 2023
Location: Washington

iTrader: (0)

Hey. I’ve got a 2018 F87 M2, and I’m getting the same issue. Idles low, stalls sometimes. But it runs fine when driving. I did the MAF trick where I unplugged it for 10m and it worked for a day, car had no issues the whole day. I’m thinking I need to replace the MAF sensor. Has anyone had this issue and had luck when replacing the MAF sensor?
Appreciate 0
      04-16-2023, 02:18 AM   #7
BadgerDog
Private First Class
BadgerDog's Avatar
178
Rep
167
Posts

Drives: 2017 BMW M2
Join Date: Jul 2020
Location: United States

iTrader: (0)

Garage List
2017 BMW M2  [9.50]
Quote:
Originally Posted by TheAMackAttack View Post
Yea my car is having a similar issue that I haven't noticed before. On cold start, RPMs start at ~1000, drop down to 500-600 for a second and the engine sounds like it's almost going to stall, and then it shoots up to 2000 real quick. I presume the latter part is normal for the cold start mechanism but the 500-600 bit seems weird.

I just moved to Colorado where the highest rated gas I can find is 91, but that alone wouldn't be bad enough to cause this, right? Can anyone comment on what the cold start mechanism normally is and if mine is indeed abnormal?
No, thats the same cheap crap thats all I can find here (in socal). Mine runs fine on it, despite not being ideal.
Appreciate 0
      04-16-2023, 04:53 AM   #8
F87source
Major General
F87source's Avatar
No_Country
7178
Rep
7,342
Posts

Drives: Bmw M2
Join Date: Aug 2018
Location: .

iTrader: (1)

Quote:
Originally Posted by mikeyryap View Post
Hey. I’ve got a 2018 F87 M2, and I’m getting the same issue. Idles low, stalls sometimes. But it runs fine when driving. I did the MAF trick where I unplugged it for 10m and it worked for a day, car had no issues the whole day. I’m thinking I need to replace the MAF sensor. Has anyone had this issue and had luck when replacing the MAF sensor?
Do you have an aftermarket intake? If so which one?


Sometimes intakes can be the cause of these issues, because it changes the way the maf sensor reads air flow. I think the root cause of this can be due to the maf sensor housing being poorly designed, so not only does it make the sensor read air flow inaccurately, but it could also not seal the maf sensor area correctly and allow air to leak by.
__________________
Click on the link below to see a compiled list of every review I have ever written:
https://f87.bimmerpost.com/forums/sh...2#post30368242
Appreciate 1
///MPhatic13540.00
      04-16-2023, 12:05 PM   #9
mikeyryap
Private
mikeyryap's Avatar
9
Rep
78
Posts

Drives: F87 M2
Join Date: Feb 2023
Location: Washington

iTrader: (0)

I do have an aftermarket intake. CTS turbo cold air intake. Is there a way to fix it?
Appreciate 0
      04-16-2023, 02:34 PM   #10
F87source
Major General
F87source's Avatar
No_Country
7178
Rep
7,342
Posts

Drives: Bmw M2
Join Date: Aug 2018
Location: .

iTrader: (1)

Quote:
Originally Posted by mikeyryap View Post
I do have an aftermarket intake. CTS turbo cold air intake. Is there a way to fix it?
No this issue shouldn't be occuring with the cts intake. I'm not really sure why it's happening to you.
__________________
Click on the link below to see a compiled list of every review I have ever written:
https://f87.bimmerpost.com/forums/sh...2#post30368242
Appreciate 0
      04-16-2023, 02:37 PM   #11
mikeyryap
Private
mikeyryap's Avatar
9
Rep
78
Posts

Drives: F87 M2
Join Date: Feb 2023
Location: Washington

iTrader: (0)

I’m thinking it’s the MAF sensor because look what FCP euro says.
Attached Images
 
Appreciate 0
      04-16-2023, 03:01 PM   #12
F87source
Major General
F87source's Avatar
No_Country
7178
Rep
7,342
Posts

Drives: Bmw M2
Join Date: Aug 2018
Location: .

iTrader: (1)

Quote:
Originally Posted by mikeyryap View Post
I’m thinking it’s the MAF sensor because look what FCP euro says.
Yes I know, that's why I asked about your intake. Maybe you should try cleaning your maf sensor with crc maf cleaner.
__________________
Click on the link below to see a compiled list of every review I have ever written:
https://f87.bimmerpost.com/forums/sh...2#post30368242
Appreciate 0
      04-16-2023, 03:03 PM   #13
mikeyryap
Private
mikeyryap's Avatar
9
Rep
78
Posts

Drives: F87 M2
Join Date: Feb 2023
Location: Washington

iTrader: (0)

Yeah maybe. But my car was in the shop with the stock air box disconnected for awhile so I’m thinking it genuinely got damaged in that process
Appreciate 0
      04-16-2023, 04:40 PM   #14
F87source
Major General
F87source's Avatar
No_Country
7178
Rep
7,342
Posts

Drives: Bmw M2
Join Date: Aug 2018
Location: .

iTrader: (1)

Quote:
Originally Posted by mikeyryap View Post
Yeah maybe. But my car was in the shop with the stock air box disconnected for awhile so I’m thinking it genuinely got damaged in that process
you could always replace the sensor if you wanted, but I'm not sure the sensor could be damage by sitting in the intake.
__________________
Click on the link below to see a compiled list of every review I have ever written:
https://f87.bimmerpost.com/forums/sh...2#post30368242
Appreciate 0
      04-16-2023, 04:49 PM   #15
mikeyryap
Private
mikeyryap's Avatar
9
Rep
78
Posts

Drives: F87 M2
Join Date: Feb 2023
Location: Washington

iTrader: (0)

But the how did the MAF sensor trick work? I disconnected and let it run for 10m and then plugged it back and all day it ran like a gem. So that shows me it was the sensor
Appreciate 0
      04-16-2023, 05:12 PM   #16
mikeyryap
Private
mikeyryap's Avatar
9
Rep
78
Posts

Drives: F87 M2
Join Date: Feb 2023
Location: Washington

iTrader: (0)

I have a code P0133 which is slow response. I’m not getting any codes related to intake or MAF, however it is stalling / running bad on cold starts. So it has to be the MAF unless I’m mistaken
Appreciate 0
      04-16-2023, 05:36 PM   #17
F87source
Major General
F87source's Avatar
No_Country
7178
Rep
7,342
Posts

Drives: Bmw M2
Join Date: Aug 2018
Location: .

iTrader: (1)

Quote:
Originally Posted by mikeyryap View Post
But the how did the MAF sensor trick work? I disconnected and let it run for 10m and then plugged it back and all day it ran like a gem. So that shows me it was the sensor
Interesting, but that is kind of strange. Because when you unplug the maf, the car will freak out because it cannot see the maf sensor anymore then it will switch to speed density mode (running only on the TMAP sensor - essentially how the N54 does it). So this means when the maf is unplugged the car should be running speed density only, so any maf sensor related issues will be eliminated. But when you plug the maf sensor back in it should switch back to running off of the maf sensor and your issues should also return. But it doesn't in your case, you said it works all day just fine. So that is kind of concerning to me because it's not consistent with the maf sensor being installed.

So let me ask you, does this only happen on cold starts? Or does it happen on warm starts too?

Otherwise if you want you can just try a new maf sensor, it is your choice. Personally I would try to clean it first.

Quote:
Originally Posted by mikeyryap View Post
I have a code P0133 which is slow response. I’m not getting any codes related to intake or MAF, however it is stalling / running bad on cold starts. So it has to be the MAF unless I’m mistaken
What are the BMW specific codes?

Wait, so does it only occur on cold starts?
__________________
Click on the link below to see a compiled list of every review I have ever written:
https://f87.bimmerpost.com/forums/sh...2#post30368242
Appreciate 0
      04-16-2023, 09:08 PM   #18
mikeyryap
Private
mikeyryap's Avatar
9
Rep
78
Posts

Drives: F87 M2
Join Date: Feb 2023
Location: Washington

iTrader: (0)

So it’s sort of random. Most of the time it was bad on cold starts. RPMs would jump, then drop. Then sometimes it even stalled. Othertime times it ran fine then sometimes woukd drop RPMs, and stall in park.

This is the thing with the MAF. I agree it could be it. But then at the same time why didn’t it happen before, and only started occurring when the downpipe was installed.

Hence brings me to my conclusion I think. I currently have a CEL from “Slow Response” from O2 sensor. I cleared it multiple times and it came back about two hours later each time. So I’m thinking the error was always there, even at first when it didn’t throw a CEL, but that was the reason my car would run bad. And now the issue is finally recognized after the car getting used to the downpipe. So now I think it’s caused from the slow response from O2 sensor because that can easily have symptoms of stalling car and weird idles etc.

Make sense?
Appreciate 0
      04-17-2023, 04:17 AM   #19
carchrism5
Lieutenant Colonel
carchrism5's Avatar
United_States
332
Rep
1,581
Posts

Drives: M2, X3 M40i, 911
Join Date: Jun 2007
Location: NC

iTrader: (3)

How long has this issue been present? I chased down a similar one for a month, then went away and oddly came back the same time the next year. Then I realized it was pretty close to the switch in summer-grade gasoline, which is occurring around now in certain places. If this has only happened very recently, especially on one tank of gas, try a different gas station.
Appreciate 0
      04-28-2023, 11:10 AM   #20
Tes
Private First Class
108
Rep
129
Posts

Drives: 2018 BMW M2
Join Date: Jun 2020
Location: Alberta

iTrader: (0)

Garage List
2018 BMW M2  [0.00]
My first start up after storing the car over winter had this exact issue. RPM dropped to 400/500 and almost stalled. I use 91 octane with fuel stabilizer storing the car over winter.

I drove the car almost empty and filled it up with fresh 94. Haven't happened again.
Appreciate 0
      04-28-2023, 01:56 PM   #21
F87source
Major General
F87source's Avatar
No_Country
7178
Rep
7,342
Posts

Drives: Bmw M2
Join Date: Aug 2018
Location: .

iTrader: (1)

Quote:
Originally Posted by Tes View Post
My first start up after storing the car over winter had this exact issue. RPM dropped to 400/500 and almost stalled. I use 91 octane with fuel stabilizer storing the car over winter.

I drove the car almost empty and filled it up with fresh 94. Haven't happened again.
What 94 do you use? Petro Canada is notorious for having horrible winter gas that performs even worse than shell 91.
__________________
Click on the link below to see a compiled list of every review I have ever written:
https://f87.bimmerpost.com/forums/sh...2#post30368242
Appreciate 0
      04-28-2023, 03:16 PM   #22
Tes
Private First Class
108
Rep
129
Posts

Drives: 2018 BMW M2
Join Date: Jun 2020
Location: Alberta

iTrader: (0)

Garage List
2018 BMW M2  [0.00]
Quote:
Originally Posted by F87source View Post
What 94 do you use? Petro Canada is notorious for having horrible winter gas that performs even worse than shell 91.
I use Esso. I only run 94 in the summer when I'm driving the car since I think most of them have ethanol. When I stored my car I used co-op 91 since I heard they don't have ethanol in the 91.
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 07:30 PM.




m2
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST