N54Tech.com - Your Source for International Turbo BMW Racing Discussion
(#1)
Old
scott60158 scott60158 is offline
New Member
 
Posts: 14
Join Date: Apr 2016
Car: BMW N54 335i
Default Cold Start Rough/Hunting Idle - 07-22-2017, 12:34 PM

I am trying to troubleshoot a rough/hunting idle: Car cranks and starts immediately, then it seems to search for the right rpm 850-550-700-650 and sometimes I feel a slight miss but never sets any codes off. After around 10 seconds it idles smooth. If I restart the car when it is warm or hasnt sat overnight it idles smooth as well immediately, so it is only when COLD starting. No misfires codes ever, even under heavy load 3rd gear 2k to redline. Boost is hitting within target. Idling when warm is smooth as silk.

-Injectors are new index 12 replaced 15k miles ago
-Coils were changed Bosch OEM when I did injectors
-Changed valve cover a few weeks ago after found hairline crack/some oil leaking
-Just replaced all new bosch oem spark plugs since oil leaked on old ones
-Valves walnut blasted 15k miles ago
-All vacuum lines replaced with high temp silicone, no leaks found

Things to try:
-Techron fuel injector cleaner (I was traveling around when this started and didn't get gas at the usual shell so maybe some bad gas gummed up injectors?)
-Clean Intake MAP sensor
-Reflash without MHD cold start delete
-Reset adaptations
-O2 sensors?? (Since I have ******* ********* and JB4 would my car hide the code if there was an issue with an O2 sensor? How would I know?)


Suggestions? Can I rule out coils since they are practically new and not throwing codes? Could a new index 12 injector fail with no codes?


2009 BMW 335i E92 N54 Jet Black, Black Dakota Leather, Bamboo Anthracite Trim: JB4 G5 ISO/MHD Backend PUMP FLASH, WHITE BMS DCI, Tial BOV, CP-E Charge Pipe, VRSF ********* **

Future: VRSF 7inch FMIC, BMS METH KIT

Last edited by scott60158; 07-22-2017 at 12:43 PM..
Reply With Quote
(#2)
Old
THE BEAST THE BEAST is offline
Junior Member
 
Posts: 308
Join Date: Apr 2016
Car: 2008 E93
Default 07-22-2017, 01:38 PM

Have you tried the pedal reset ? It worked for me with similar symptoms.
Reply With Quote
(#3)
Old
scott60158 scott60158 is offline
New Member
 
Posts: 14
Join Date: Apr 2016
Car: BMW N54 335i
Default 07-22-2017, 01:54 PM

Quote:
Originally Posted by THE BEAST
Have you tried the pedal reset ? It worked for me with similar symptoms.
Is that the same as resetting throttle adaptations in mhd?

I just did that and it seems ok I will see what happens tomorrow after it sits overnight. I also turned off cold start delete now it does the normal 1k rpm cold start and slowly drops down to 650 idle with a/c.


2009 BMW 335i E92 N54 Jet Black, Black Dakota Leather, Bamboo Anthracite Trim: JB4 G5 ISO/MHD Backend PUMP FLASH, WHITE BMS DCI, Tial BOV, CP-E Charge Pipe, VRSF ********* **

Future: VRSF 7inch FMIC, BMS METH KIT
Reply With Quote
(#4)
Old
THE BEAST THE BEAST is offline
Junior Member
 
Posts: 308
Join Date: Apr 2016
Car: 2008 E93
Default 07-22-2017, 02:01 PM

No, its different. My car started hunting for idle when I did the mhd throttle reset and the peddle reset fixed it instantly.
Reply With Quote
(#5)
Old
scott60158 scott60158 is offline
New Member
 
Posts: 14
Join Date: Apr 2016
Car: BMW N54 335i
Default 07-22-2017, 02:04 PM

Quote:
Originally Posted by THE BEAST
No, its different. My car started hunting for idle when I did the mhd throttle reset and the peddle reset fixed it instantly.
What is the procedure for it I vaguely remember its ignition on hold down pedal 30 seconds? Then what?


2009 BMW 335i E92 N54 Jet Black, Black Dakota Leather, Bamboo Anthracite Trim: JB4 G5 ISO/MHD Backend PUMP FLASH, WHITE BMS DCI, Tial BOV, CP-E Charge Pipe, VRSF ********* **

Future: VRSF 7inch FMIC, BMS METH KIT
Reply With Quote
(#6)
Old
THE BEAST THE BEAST is offline
Junior Member
 
Posts: 308
Join Date: Apr 2016
Car: 2008 E93
Default 07-22-2017, 02:08 PM

Im not quite sure. But I believe its ign on, pedal to the floor, wait 30 seconds, ign off, then release pedal. Then start. Mine went away as soon as I did this.
Reply With Quote
(#7)
Old
535SFC 535SFC is offline
New Member
 
Posts: 2
Join Date: Jul 2017
Car: 2008 535XI
Default 07-22-2017, 05:14 PM

My car was behaving similarly earlier this year. The dealer in Des Moines had the car for 5 weeks (for repeat cold starts in cold weather and a slew of other work) and finally diagnosed it as a low pressure fuel pump, or the solenoid? I can't remember now. Has not had a problem since. Minus the new turbos being installed while I'm overseas lol!
Reply With Quote
(#8)
Old
scott60158 scott60158 is offline
New Member
 
Posts: 14
Join Date: Apr 2016
Car: BMW N54 335i
Default 07-22-2017, 05:20 PM

Quote:
Originally Posted by 535SFC
My car was behaving similarly earlier this year. The dealer in Des Moines had the car for 5 weeks (for repeat cold starts in cold weather and a slew of other work) and finally diagnosed it as a low pressure fuel pump, or the solenoid? I can't remember now. Has not had a problem since. Minus the new turbos being installed while I'm overseas lol!
hmmm, did it have any lpfp codes?


2009 BMW 335i E92 N54 Jet Black, Black Dakota Leather, Bamboo Anthracite Trim: JB4 G5 ISO/MHD Backend PUMP FLASH, WHITE BMS DCI, Tial BOV, CP-E Charge Pipe, VRSF ********* **

Future: VRSF 7inch FMIC, BMS METH KIT
Reply With Quote
(#9)
Old
535SFC 535SFC is offline
New Member
 
Posts: 2
Join Date: Jul 2017
Car: 2008 535XI
Default 07-22-2017, 05:31 PM

It originally threw a hpfp code which started the whole dealer adventure. I was told the lpfp had starved the hpfp which is why it threw the code (hpfp was still under BMW warranty which sounded fishy) however it worked.
Reply With Quote
(#10)
Old
Blaizon Blaizon is offline
Junior Member
 
Posts: 108
Join Date: Dec 2009
Car: 2008 E92
Default 07-23-2017, 04:00 AM

I had similar symptons as you starting a few weeks ago. In the end my HPFP was failing and finally died last week. I swapped it out Friday and now's she's good again.


2008 Sparking Graphite 335i 6MT Coupe - JB4/FFTEC
2007 Montego Blue 335i 6AT Sedan
Reply With Quote
(#11)
Old
roywillems roywillems is offline
New Member
 
Posts: 12
Join Date: Nov 2016
Car: 335i
Default 07-23-2017, 04:16 AM

Exact same problems, it drove me crazy, also new injectors etcetc, i deleted the cold start delete in mhd and now its starting fine,
Reply With Quote
(#12)
Old
scott60158 scott60158 is offline
New Member
 
Posts: 14
Join Date: Apr 2016
Car: BMW N54 335i
Default 07-23-2017, 11:48 PM

i think deleting the cold start and changing the throttle adaptations fixed my issue. It seems like my car just didn't get along with the cold start mhd delete anymore for whatever reason.


2009 BMW 335i E92 N54 Jet Black, Black Dakota Leather, Bamboo Anthracite Trim: JB4 G5 ISO/MHD Backend PUMP FLASH, WHITE BMS DCI, Tial BOV, CP-E Charge Pipe, VRSF ********* **

Future: VRSF 7inch FMIC, BMS METH KIT
Reply With Quote
(#13)
Old
mhigham mhigham is offline
New Member
 
Posts: 28
Join Date: Mar 2017
Car: 2009 BMW 335i
Default 07-25-2017, 10:33 AM

Mine does the exact same thing. New coils and plugs, walnut blast, etc. Dealer diagnosed it as needing -12 injectors.but warranty wouldn't cover it without a misfire code. After about 10 seconds it's as smooth as can be. I've just leaned to live with it until I feel like removing the JB4 and settting a code. It does do it a lot less without JB4, so I've just attributed it to being tuned.
Reply With Quote
(#14)
Old
AZN54 AZN54 is offline
Junior Member
 
Posts: 211
Join Date: Oct 2015
Car: N54 135i
Default 07-27-2017, 10:03 AM

Sounds like it's a bad/leaky injector/injectors. When it sits overnight, a leaky injector drips fuel into the cylinder, causing it to run rough and misfire upon cold start. The reason it doesn't have the same hunting RPM's or misfire on a warm start, or when it's only been sitting for a little while, is because the injector hasn't had time to leak a significant amount of fuel into the cylinder. The car should still pull fine even with a leaky injector and might go for sometime without triggering a code. You could pull the plugs and check to see if one is black and smells like fuel. You can also try to get a cold start log to see if there is any AFR variations between banks. Just my $.02


2009 135i
FBO, MMP Inlets, Stage 2 LPFP, MHD e40, Alpina B3

Offering Arizona Walnut Blasting Service:
http://www.n54tech.com/forums/showthread.php?t=36741
Reply With Quote
(#15)
Old
AutoEngBM95's Avatar
AutoEngBM95 AutoEngBM95 is offline
New Member
 
Posts: 22
Join Date: Sep 2017
Car: 2009 E90 335xi LCI
Default 10-12-2017, 10:56 AM

Similar issue here... however there are a few differences. My car will start immediately and rpm hunt and occasionally almost stall on cold start. This only occasionally happens when ambient temperatures are below 5C (41F). Then idles and runs fine after a couple of minutes and warm. No codes thrown. No issues in the summer. No idea what it could be.....


2009 E90 335xi LCI
BMS Dual Cone Intake
BMS JB4 Map 5
Mishimoto Oil Catch Can
OEM Rebuilt Turbos from Turbo Lab of America
Ctls DwnPps
Custom Ctls Midpipes
Max Brakes Carbon Ceramic pads, cross drilled and slotted rotors
Exhaust Flap Unplug
RTX GRAZ Wheels
Ontario, Canada
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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

Forum Jump




vBulletin Skin developed by: vBStyles.com
Copyright 2007 - 2017, N54tech.com