GetBMWParts
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read

Go Back   BMW M3 and BMW M4 Forum > BMW F80 M3 / F82 M4 Forum > BMW M3 (F80) and BMW M4 (F82) General Forum

Post Reply
 
Thread Tools Search this Thread
      11-20-2017, 04:44 PM   #1
Racer35
Tombarra Stalker
United_States
28
Rep
67
Posts

Drives: 2017 M3 ZCP, Mineral Grey
Join Date: Jul 2016
Location: Danville, CA

iTrader: (0)

6MT Erratic Idle

Has anyone else had an issue with erratic idle (with a stock ECU)? My 6MT is about a year old, with 17K miles, and I've noticed a stumble at stop lights over the last couple months. Idle oscillates between 500 and 750 RPM, stumbling at 500. It was only occasional a couple months ago but it happens every time now. This happens with all ECU modes and doesn't seem to have anything to do with where I buy my gas. Until recently, idle was dead-nuts-steady. Wondering if I have a bad sensor somewhere.
Appreciate 0
      11-20-2017, 06:17 PM   #2
jasnh
Lieutenant
jasnh's Avatar
United_States
129
Rep
460
Posts

Drives: 2015 M3 Austin Yellow
Join Date: Jun 2013
Location: NH

iTrader: (0)

Garage List
Quote:
Originally Posted by Racer35 View Post
Has anyone else had an issue with erratic idle (with a stock ECU)? My 6MT is about a year old, with 17K miles, and I've noticed a stumble at stop lights over the last couple months. Idle oscillates between 500 and 750 RPM, stumbling at 500. It was only occasional a couple months ago but it happens every time now. This happens with all ECU modes and doesn't seem to have anything to do with where I buy my gas. Until recently, idle was dead-nuts-steady. Wondering if I have a bad sensor somewhere.
I recently had to have a fuel pressure sensor/module replaced on my 2015 with 22K miles.....my car showed some similar symptoms and then a few weeks later sputtered and died at a stop light, and it took me a few tries to get it started again....and I got a Drivetrain Malfunction error because of it.
__________________
On Order: 2018 M3 Atlantis Blue/SS, Comp Pkg, 6MT
Current: 2015 M3 Austin Yellow
Appreciate 1
      11-21-2017, 10:09 PM   #3
mrcheezle19
First Lieutenant
180
Rep
385
Posts

Drives: e30 turbo
Join Date: Nov 2013
Location: lake elsinore

iTrader: (0)

I feel like this happened to my car once when it was about 2 months old (M2). Almost died, but then idled fine and hasn't done it since. Never had it checked out, but still odd.
__________________
Present: M2 Mineral Grey 6MT

Past: BMW e30 m52 turbo 628whp/558wtq
Appreciate 0
      11-22-2017, 01:14 AM   #4
Racer35
Tombarra Stalker
United_States
28
Rep
67
Posts

Drives: 2017 M3 ZCP, Mineral Grey
Join Date: Jul 2016
Location: Danville, CA

iTrader: (0)

Quote:
Originally Posted by jasnh View Post
Quote:
Originally Posted by Racer35 View Post
Has anyone else had an issue with erratic idle (with a stock ECU)? My 6MT is about a year old, with 17K miles, and I've noticed a stumble at stop lights over the last couple months. Idle oscillates between 500 and 750 RPM, stumbling at 500. It was only occasional a couple months ago but it happens every time now. This happens with all ECU modes and doesn't seem to have anything to do with where I buy my gas. Until recently, idle was dead-nuts-steady. Wondering if I have a bad sensor somewhere.
I recently had to have a fuel pressure sensor/module replaced on my 2015 with 22K miles.....my car showed some similar symptoms and then a few weeks later sputtered and died at a stop light, and it took me a few tries to get it started again....and I got a Drivetrain Malfunction error because of it.
That sounds about right. I don't have a malfunction light yet, but haven't had it stall... Hopefully they'll be able to diagnose it easily without error codes.
Appreciate 0
      11-22-2017, 09:40 AM   #5
HPIA4v2
Captain
46
Rep
895
Posts

Drives: E60, E71, E92
Join Date: May 2007
Location: Washington

iTrader: (3)

Quote:
Originally Posted by jasnh View Post
I recently had to have a fuel pressure sensor/module replaced on my 2015 with 22K miles.....my car showed some similar symptoms and then a few weeks later sputtered and died at a stop light, and it took me a few tries to get it started again....and I got a Drivetrain Malfunction error because of it.
Dang, similar issue with low-pressure fuel pump sensor ala N54.
Appreciate 0
      11-22-2017, 10:30 AM   #6
shortseller
Colonel
shortseller's Avatar
United_States
398
Rep
2,668
Posts

Drives: 2015 SO M3
Join Date: Aug 2010
Location: NOVA

iTrader: (0)

Quote:
Originally Posted by HPIA4v2 View Post
Dang, similar issue with low-pressure fuel pump sensor ala N54.
Yeah, sounds like HPFP and/or injector banks similiar to what they had with the N54 you reference above. Which BMW did resolve with replacements of the items above and software adjustments.

OP, as stated it can leave you high & dry at a stop light without notice once these symptoms start, thus getting it looked at by BMW sooner than later is prudent.
__________________
Appreciate 1
      11-22-2017, 12:16 PM   #7
HPIA4v2
Captain
46
Rep
895
Posts

Drives: E60, E71, E92
Join Date: May 2007
Location: Washington

iTrader: (3)

Quote:
Originally Posted by shortseller View Post
Yeah, sounds like HPFP and/or injector banks similiar to what they had with the N54 you reference above. Which BMW did resolve with replacements of the items above and software adjustments.

OP, as stated it can leave you high & dry at a stop light without notice once these symptoms start, thus getting it looked at by BMW sooner than later is prudent.
not 100% sure, but his issue seems to be not HPFP/injectors but the sensor that monitor the low-pressure fuel pump, LPFP. on N54 it went bad, reads high so LPFP backs-out in reality starving the HPFP, engine stalls, sometime on low speed. Very scary situation on N54, if you happens to turn left across oncoming traffic, it happened to me. it's $75 sensor under air-intake on N54.
Appreciate 1
      11-22-2017, 01:01 PM   #8
shortseller
Colonel
shortseller's Avatar
United_States
398
Rep
2,668
Posts

Drives: 2015 SO M3
Join Date: Aug 2010
Location: NOVA

iTrader: (0)

Quote:
Originally Posted by HPIA4v2 View Post
not 100% sure, but his issue seems to be not HPFP/injectors but the sensor that monitor the low-pressure fuel pump, LPFP. on N54 it went bad, reads high so LPFP backs-out in reality starving the HPFP, engine stalls, sometime on low speed. Very scary situation on N54, if you happens to turn left across oncoming traffic, it happened to me. it's $75 sensor under air-intake on N54.
...probably right but in any event getting it checked before it puts you in a dangerous situation is good advise.
__________________
Appreciate 0
      11-23-2017, 02:32 PM   #9
Racer35
Tombarra Stalker
United_States
28
Rep
67
Posts

Drives: 2017 M3 ZCP, Mineral Grey
Join Date: Jul 2016
Location: Danville, CA

iTrader: (0)

Alright... I was hoping to wait until my next oil change (2,000 miles away) but I don't want it to leave me hanging. I'll get it scheduled and report back. Thanks for the advice.
Appreciate 0
      11-28-2017, 01:12 AM   #10
sycd
Lieutenant
sycd's Avatar
United_States
45
Rep
557
Posts

Drives: F80 YMB 6MT
Join Date: Mar 2008
Location: USA

iTrader: (0)

Garage List
2015 M3  [0.00]
2013 X5 50i  [0.00]
Quote:
Originally Posted by HPIA4v2 View Post
not 100% sure, but his issue seems to be not HPFP/injectors but the sensor that monitor the low-pressure fuel pump, LPFP. on N54 it went bad, reads high so LPFP backs-out in reality starving the HPFP, engine stalls, sometime on low speed. Very scary situation on N54, if you happens to turn left across oncoming traffic, it happened to me. it's $75 sensor under air-intake on N54.
I went through so many sets of injectors and fuel pumps in my E92 335i I loved that car, but couldn't afford the risk once the warranty was over.

Another potential culprit for erratic idle is a faulty or dirty MAF.
__________________
2015 M3 6MT | Yas Marina Blue, CF Roof, Cloth | Adaptive M Susp, 437M 19" Silver | MPE
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 -4. The time now is 02:19 AM.




f80post
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
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