BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read
Go Back   6Post.com | BMW 6-Series Forum > BMW 6 Series Forum > BMW M6 Forum (F12 / F13)

Post Reply
 
Thread Tools Search this Thread
      12-19-2020, 04:18 PM   #1
m6NYC
Private
m6NYC's Avatar
20
Rep
80
Posts

Drives: 2015 BMW M6 Gran Coupé
Join Date: Feb 2020
Location: Brooklyn New York

iTrader: (0)

Stalling at every cold start & 7mpg

Current mods are:

Catless downpipes
Full 3in IPE exhaust
VRSF Intercoolers
methanol injection without Jb4 map0
gapped ngk plugs
DME stage 2 tune
bcm with jb4
upgraded SSP clutches
afe cold air intakes
stage 1 turbos
Cold start delete
Probably something Im missing but nothing out of the ordinary.

The roughest cold start I've ever seen. The RPMs fluctuate by 5-600 rpms up to 1200 then drop back down to 600 continuously over and over until the engine stalls. 0 codes on the car but I've been getting around 6-8mpg and my cold start will always stall the car unless its being driven right away or revved. Its been getting worse with colder climate, but completely disappears after 1-2minutes of driving.

I've always been averaging between 6-8miles per gallon in city driving. Rarely go over 5k rpm in Manhattan, but I always try to use the entire RPM range every drive.

I believe the idle possibly has to be adjusted? any ideas on how to do this?

Last edited by m6NYC; 12-19-2020 at 05:28 PM..
Appreciate 0
      12-20-2020, 12:03 PM   #2
Spacecpe
First Lieutenant
Canada
38
Rep
346
Posts

Drives: E90 335i Msport
Join Date: Sep 2014
Location: Winnipeg, Mb Canada

iTrader: (0)

Sounds like a leaky injector.. no codes popping up?
Appreciate 0
      12-21-2020, 10:11 AM   #3
m6NYC
Private
m6NYC's Avatar
20
Rep
80
Posts

Drives: 2015 BMW M6 Gran Coupé
Join Date: Feb 2020
Location: Brooklyn New York

iTrader: (0)

Quote:
Originally Posted by Spacecpe View Post
Sounds like a leaky injector.. no codes popping up?
I had at one point thought the same since BMW has an extended warranty on their injectors until January 2015. My car was produced February 2015 and has the updated index injectors however the car is showing 0 codes whatsoever and that is throwing me off.

I will looking into this though. Thanks for mentioning it
Appreciate 0
      12-21-2020, 01:44 PM   #4
m6NYC
Private
m6NYC's Avatar
20
Rep
80
Posts

Drives: 2015 BMW M6 Gran Coupé
Join Date: Feb 2020
Location: Brooklyn New York

iTrader: (0)

Here is a video of the RPMs oscillating. Usually it jumps from 600-1200rpms continuously. Seems to have gotten worse after my cold start delete.
https://vimeo.com/493476826



ANOTHER UPDATE:
performed the smooth running test through ISTA+ and not surprisingly the flow rates of all 8 injectors are within range. Had they weren't, I would've received a code.
[/U][/I][/B]

Last edited by m6NYC; 12-21-2020 at 03:23 PM..
Appreciate 0
      12-21-2020, 07:08 PM   #5
BLACK KILLER
New Member
BLACK KILLER's Avatar
Germany
41
Rep
29
Posts

Drives: BMW'16 M6GC
Join Date: Jan 2020
Location: Baden Baden

iTrader: (0)

Garage List
I dare to assume that irreversible changes have occurred in the cylinders. What is the consumption of engine oil?
Appreciate 0
      12-21-2020, 09:11 PM   #6
Blaxwil
First Lieutenant
194
Rep
351
Posts

Drives: 2015 M5
Join Date: Feb 2018
Location: Atlanta

iTrader: (0)

I'm a F10 M5 guy lurking around and saw this post. Have you tried cleaning the MAF sensors? I had a similar idling issue (not the fuel consumption issue) that was quickly resolved when I cleaned my MAF's.
Appreciate 0
      12-21-2020, 09:22 PM   #7
m6NYC
Private
m6NYC's Avatar
20
Rep
80
Posts

Drives: 2015 BMW M6 Gran Coupé
Join Date: Feb 2020
Location: Brooklyn New York

iTrader: (0)

Quote:
Originally Posted by BLACK KILLER View Post
I dare to assume that irreversible changes have occurred in the cylinders. What is the consumption of engine oil?
I'm consuming 1 quart every 1800 miles. I've had poor oil consumption in the past but its since corrected after using the full rpm range.
Appreciate 0
      12-21-2020, 09:23 PM   #8
m6NYC
Private
m6NYC's Avatar
20
Rep
80
Posts

Drives: 2015 BMW M6 Gran Coupé
Join Date: Feb 2020
Location: Brooklyn New York

iTrader: (0)

Quote:
Originally Posted by Blaxwil View Post
I'm a F10 M5 guy lurking around and saw this post. Have you tried cleaning the MAF sensors? I had a similar idling issue (not the fuel consumption issue) that was quickly resolved when I cleaned my MAF's.
I have already tried cleaning the maf sensors unfortunately with no resolution
Appreciate 0
      12-21-2020, 09:32 PM   #9
m6NYC
Private
m6NYC's Avatar
20
Rep
80
Posts

Drives: 2015 BMW M6 Gran Coupé
Join Date: Feb 2020
Location: Brooklyn New York

iTrader: (0)

https://vimeo.com/493590712Updated video of it stalling.
Appreciate 0
      12-22-2020, 12:52 AM   #10
Spacecpe
First Lieutenant
Canada
38
Rep
346
Posts

Drives: E90 335i Msport
Join Date: Sep 2014
Location: Winnipeg, Mb Canada

iTrader: (0)

Mmmmm.. very strange that it's not throwing any codes. Aside from the MAF it could be related to the battery.. there was a thread running around a while ago with same symptoms, rough cold start and all that jazz.. ended up being a bad battery to everybody's surprise.
Appreciate 0
      12-22-2020, 04:46 AM   #11
Mr. M6
FEEL THE POWER
Mr. M6's Avatar
Bahrain
103
Rep
407
Posts

Drives: M6 GC
Join Date: Jan 2018
Location: Bahrain

iTrader: (0)

Garage List
2014 BMW M6 GC  [4.50]
replace MAF or injectors, i was having leaky injectors before without any codes & checked them with ISTA showing all good, replaced later and all fine now, good luck
__________________
M6 GC CP + AMS CATLESS DP + AKRAPOVIC EXHAUST + MSR INTAKE=
Appreciate 0
      12-22-2020, 12:56 PM   #12
m6NYC
Private
m6NYC's Avatar
20
Rep
80
Posts

Drives: 2015 BMW M6 Gran Coupé
Join Date: Feb 2020
Location: Brooklyn New York

iTrader: (0)

Quote:
Originally Posted by Spacecpe View Post
Mmmmm.. very strange that it's not throwing any codes. Aside from the MAF it could be related to the battery.. there was a thread running around a while ago with same symptoms, rough cold start and all that jazz.. ended up being a bad battery to everybody's surprise.
Strange indeed, Im assuming if the injectors are leaking fuel overnight it wouldn't throw an error because their fuel flow during operation is normal.

I just re-cleaned the MAFs this morning and replaced/recoded a new oem battery this past February. Also added a bottle of seafoam fuel injector cleaner to full tank of gas last week with no resolution or improvement.

Quote:
Originally Posted by Mr. M6 View Post
replace MAF or injectors, i was having leaky injectors before without any codes & checked them with ISTA showing all good, replaced later and all fine now, good luck
Could you explain the symptoms you were getting with the leaky injectors? I had the car parked and not driven for almost 5 days and it stalled 4-5 times idling but it was also 10-15 degrees F which is the coldest it has been in New York this season. I was looking for the obvious lack of power symptoms you would see with failing injectors but its hard to notice any power dips with 780wheel horsepower.
Appreciate 0
      12-22-2020, 07:28 PM   #13
Spacecpe
First Lieutenant
Canada
38
Rep
346
Posts

Drives: E90 335i Msport
Join Date: Sep 2014
Location: Winnipeg, Mb Canada

iTrader: (0)

A sure way of ruling out injectors is pulling plugs in the morning to see if they are wet and smell of gas.
Leaky injectors, will give you a rough cold start (like yours) and in about 40sec the car will run fine, will pull hard and nothing will seem off. The issue is while trying to figure it out, you could be diluting your oil with that fuel and ruining your bearings.
Appreciate 0
      12-26-2020, 04:09 AM   #14
Mr. M6
FEEL THE POWER
Mr. M6's Avatar
Bahrain
103
Rep
407
Posts

Drives: M6 GC
Join Date: Jan 2018
Location: Bahrain

iTrader: (0)

Garage List
2014 BMW M6 GC  [4.50]
Quote:
Originally Posted by m6NYC View Post
Strange indeed, Im assuming if the injectors are leaking fuel overnight it wouldn't throw an error because their fuel flow during operation is normal.

I just re-cleaned the MAFs this morning and replaced/recoded a new oem battery this past February. Also added a bottle of seafoam fuel injector cleaner to full tank of gas last week with no resolution or improvement.



Could you explain the symptoms you were getting with the leaky injectors? I had the car parked and not driven for almost 5 days and it stalled 4-5 times idling but it was also 10-15 degrees F which is the coldest it has been in New York this season. I was looking for the obvious lack of power symptoms you would see with failing injectors but its hard to notice any power dips with 780wheel horsepower.

what Spacecpe said above + you will hear little ticking sound coming from the exhaust sometimes at idle
__________________
M6 GC CP + AMS CATLESS DP + AKRAPOVIC EXHAUST + MSR INTAKE=
Appreciate 0
      12-30-2020, 02:50 PM   #15
m6NYC
Private
m6NYC's Avatar
20
Rep
80
Posts

Drives: 2015 BMW M6 Gran Coupé
Join Date: Feb 2020
Location: Brooklyn New York

iTrader: (0)

Quote:
Originally Posted by Spacecpe View Post
A sure way of ruling out injectors is pulling plugs in the morning to see if they are wet and smell of gas.
Leaky injectors, will give you a rough cold start (like yours) and in about 40sec the car will run fine, will pull hard and nothing will seem off. The issue is while trying to figure it out, you could be diluting your oil with that fuel and ruining your bearings.
Thanks for this. Leaking injectors seem to be the issue here. Going to do one last smoke test to check for any vacuum leaks before I pull the plugs. I vaguely remember 1 spark plug being very wet relative to the others when changing them. I didn't understand the significance of that at the time.

Seems like this issue was going on for a good amount of time unfortunately. The surging idle was hidden by the high revving cold start and the white smoke/unburnt gas smell was removed by the catalytic converters. Only when I removed the Cats and cold start did I start to notice this issue.

I wouldn't be surprised if this is the cause of the infamous rod bearing issue with the E60/63 M5 M6 since it throws no warning issue and can continue for a relatively long amount of time until it progresses to the point of throwing an error code.

Quote:
Originally Posted by Mr. M6 View Post
what Spacecpe said above + you will hear little ticking sound coming from the exhaust sometimes at idle
Couldn't really hear any ticking from the exhaust at idle, I did hear a very very slight surge in rpms as that continues to happen even when warm. The surge is barely noticeable and less than 50 rpms.

Last edited by m6NYC; 12-30-2020 at 03:04 PM..
Appreciate 0
      01-01-2021, 09:54 PM   #16
Spacecpe
First Lieutenant
Canada
38
Rep
346
Posts

Drives: E90 335i Msport
Join Date: Sep 2014
Location: Winnipeg, Mb Canada

iTrader: (0)

Honestly with the rod bearing issues on this platform, I'd make injectors a regular maintenance item, maybe every 40k ish, new injectors. Every 10k plugs, every 15-20k all O2 sensors. And im sure everyone wouldn't have any issues
Appreciate 0
      03-04-2021, 10:12 PM   #17
m6NYC
Private
m6NYC's Avatar
20
Rep
80
Posts

Drives: 2015 BMW M6 Gran Coupé
Join Date: Feb 2020
Location: Brooklyn New York

iTrader: (0)

Quote:
Originally Posted by Spacecpe View Post
Sounds like a leaky injector.. no codes popping up?
Quote:
Originally Posted by BLACK KILLER View Post
I dare to assume that irreversible changes have occurred in the cylinders. What is the consumption of engine oil?
Quote:
Originally Posted by Mr. M6 View Post
replace MAF or injectors, i was having leaky injectors before without any codes & checked them with ISTA showing all good, replaced later and all fine now, good luck
Quote:
Originally Posted by Spacecpe View Post
Honestly with the rod bearing issues on this platform, I'd make injectors a regular maintenance item, maybe every 40k ish, new injectors. Every 10k plugs, every 15-20k all O2 sensors. And im sure everyone wouldn't have any issues
Hey guys, just to update this thread in case someone else has a similar issue.

Found out my smaller axillary coolant tank was slowly leaking, always seems empty. Turbo coolant lines were clean.
My stock plastic intercoolers had a crack and was leaking coolant into the engine.
Replaced them both with VRSF Charge Coolers and my problem is solved.
Also the AFE Cold Air Intakes were throwing off my fuel trim causing a 6-7miles per gallon. Reverted those back to stock with charcoal filter delete and my problems are solved!
Appreciate 0
      03-04-2021, 11:22 PM   #18
Spacecpe
First Lieutenant
Canada
38
Rep
346
Posts

Drives: E90 335i Msport
Join Date: Sep 2014
Location: Winnipeg, Mb Canada

iTrader: (0)

Awesome to see that you solved the issue.
So both the charge coolers and their reservoir were leaking?
That's a first for me.. how many miles?

Huge thank you for the update. Hate when people don't update their threads.
Appreciate 0
      03-05-2021, 12:25 AM   #19
m6NYC
Private
m6NYC's Avatar
20
Rep
80
Posts

Drives: 2015 BMW M6 Gran Coupé
Join Date: Feb 2020
Location: Brooklyn New York

iTrader: (0)

Quote:
Originally Posted by Spacecpe View Post
Awesome to see that you solved the issue.
So both the charge coolers and their reservoir were leaking?
That's a first for me.. how many miles?

Huge thank you for the update. Hate when people don't update their threads.
Same! Everything I learnt regarding my issue was from this forum, so it's the least I could do.
My passenger side Intercooler was the issue. It had a small crack only visible when I separated the upper and lower plastic housing from the metal center frame prior to throwing them out for how much trouble they've been causing me.
I kept finding my smaller axillary coolant tank empty every 2 or so weeks. So I checked the usual turbo coolant lines but they were completely bone dry.

Luckily for me, I had purchased the VRSF Intercoolers back in October but was too lazy to install after reading about nonretrofitting hardware. That couldn't have been anymore true. It was a pain in the ass to find 6 screws with correct threading as the stock hardware off the original intercoolers were made for plastic threads and not metal.

56k miles, driven like its stolen, daily

Last edited by m6NYC; 03-05-2021 at 12:35 AM..
Appreciate 0
      03-05-2021, 02:02 PM   #20
Spacecpe
First Lieutenant
Canada
38
Rep
346
Posts

Drives: E90 335i Msport
Join Date: Sep 2014
Location: Winnipeg, Mb Canada

iTrader: (0)

Hahaha niiice! I bet you wanted to hit that with bat
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 08:19 PM.




6post.com
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, 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