Stumbling under heavy load, partial throttle in high gears! Plugs? Carbon?

halik008 · 11-07-2013, 07:52 PM

Ok. I'm having this weird hesitating/stumbling when I'm doing highway speeds in 6th gear and get on the throttle partially to accelerate moderately. Today it goes so bad it actually I got it to throw CEL basically trying to get to stumble. Problem is the CEL goes away as soon as the stumbling does.

Here's the relevant issues.

-Car starts just fine.
-Idles just fine with seldom stumble
-Goes like hell @ WOT, no stumbles
-Stumble occurs with JB4 or stock map
-Spark plugs changed at 60K, 91K now
-Car does need 1qt between 10k oil changes, more if I bet on it at 16psi

-Stumbling is very prominent 6th, no so much in lower gears.

To me it feels like boost leak, spark plugs or injectors. But boost is fine at it seems to build up normally.

So it's down to spark plugs or injectors?

I also heard carbon build up could cause it?

Opinions?

DR-JEKL · 11-09-2013, 04:58 AM

i had a similiar issue, swapped out my coils and it improved slightly.

I was hesitant about changing plugs as they were only 8 months old but eventually i done them and bam solved my misfire issue when going wot in higher gears!

Allen@MOTIV · 11-09-2013, 09:09 AM

It sounds like you have the "autoclear" feature on the JB4 turned on because even when the conditions that trigger a CEL disappear there should still be a historic code logged.

Recreate the issue with autoclear off and pull the codes but it sounds like plugs. Usually when misfires only occur under load it is an ignition system issue.

3.1L Z · 11-15-2013, 03:28 PM

Plugs on mapped cars need to be replaced every 20-25k.
I had similar issues and plug change cleared it up.

JStang · 11-15-2013, 03:31 PM

Could have a coil on the way out or as others stated, check your plugs.

CHECKERED · 11-15-2013, 03:36 PM

Quote:

Originally Posted by 3.1L Z

Plugs on mapped cars need to be replaced every 20-25k.
I had similar issues and plug change cleared it up.

lol more like 10K...switched to one step colder iridium

, it was going to get ridicules to change plugs every other oil change.

WedgePerformance · 11-15-2013, 04:59 PM

^ +1000000000000

I had an NGK plug go bad after 5k running 15deg timing and 100% e85. Could have been a fluke, but replaced them all to be on the safe side.

dicostal · 11-15-2013, 05:08 PM

possible VANOS solenoid as well, clean it and see if it goes away. Not too big of a job.

3000GT MR · 11-15-2013, 05:15 PM

Quote:

Originally Posted by WedgePerformance

^ +1000000000000

I had an NGK plug go bad after 5k running 15deg timing and 100% e85. Could have been a fluke, but replaced them all to be on the safe side.

Yup I've had the resistor in the plug go bad before. Worked fine until high boost and high load then it would misfire

jayzF30 · 11-15-2013, 06:08 PM

Quote:

Originally Posted by WedgePerformance

^ +1000000000000

I had an NGK plug go bad after 5k running 15deg timing and 100% e85. Could have been a fluke, but replaced them all to be on the safe side.

What happened to your plugs?

WedgePerformance · 11-15-2013, 08:12 PM

Quote:

Originally Posted by jazze90

What happened to your plugs?

One fouled out cyl 4 while racing.

11-07-2013, 07:52 PM	#1
halik008 Private First Class 59 Rep 143 Posts Drives: e90 Join Date: Oct 2013 Location: United States iTrader: (0)	Stumbling under heavy load, partial throttle in high gears! Plugs? Carbon? Ok. I'm having this weird hesitating/stumbling when I'm doing highway speeds in 6th gear and get on the throttle partially to accelerate moderately. Today it goes so bad it actually I got it to throw CEL basically trying to get to stumble. Problem is the CEL goes away as soon as the stumbling does. Here's the relevant issues. -Car starts just fine. -Idles just fine with seldom stumble -Goes like hell @ WOT, no stumbles -Stumble occurs with JB4 or stock map -Spark plugs changed at 60K, 91K now -Car does need 1qt between 10k oil changes, more if I bet on it at 16psi -Stumbling is very prominent 6th, no so much in lower gears. To me it feels like boost leak, spark plugs or injectors. But boost is fine at it seems to build up normally. So it's down to spark plugs or injectors? I also heard carbon build up could cause it? Opinions?
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11-09-2013, 04:58 AM	#2
DR-JEKL Major General 908 Rep 6,285 Posts Drives: Space Grey E92 335i 6MT Join Date: Jul 2012 Location: Newcastle Ozstraylia iTrader: (3)	i had a similiar issue, swapped out my coils and it improved slightly. I was hesitant about changing plugs as they were only 8 months old but eventually i done them and bam solved my misfire issue when going wot in higher gears!
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11-09-2013, 09:09 AM	#3
Allen@MOTIV 38 Rep 634 Posts Drives: 135i Join Date: Jun 2013 Location: VA iTrader: (0)	It sounds like you have the "autoclear" feature on the JB4 turned on because even when the conditions that trigger a CEL disappear there should still be a historic code logged. Recreate the issue with autoclear off and pull the codes but it sounds like plugs. Usually when misfires only occur under load it is an ignition system issue.
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11-15-2013, 03:28 PM	#4
3.1L Z Private First Class 26 Rep 186 Posts Drives: '09 E92, Cobb AP Join Date: Jul 2012 Location: San Antonio iTrader: (0)	Plugs on mapped cars need to be replaced every 20-25k. I had similar issues and plug change cleared it up.
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11-15-2013, 03:31 PM	#5
JStang Brigadier General 571 Rep 3,627 Posts Drives: FDB M3 CS Join Date: Dec 2010 Location: St. Petersburg, FL iTrader: (9)	Could have a coil on the way out or as others stated, check your plugs.
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11-15-2013, 04:59 PM	#7
WedgePerformance BimmerPost Supporting Vendor 1341 Rep 1,701 Posts Drives: Slot Machines.. Keep Taking $ Join Date: Oct 2013 Location: Portland, OR iTrader: (0) Garage List 2007 BMW 335i Sport [9.67]	^ +1000000000000 I had an NGK plug go bad after 5k running 15deg timing and 100% e85. Could have been a fluke, but replaced them all to be on the safe side.
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11-15-2013, 05:08 PM	#8
dicostal Lieutenant 55 Rep 495 Posts Drives: 2007 335i Join Date: Jun 2010 Location: Italian in CT - USA iTrader: (0)	possible VANOS solenoid as well, clean it and see if it goes away. Not too big of a job. __________________ GIAC stage II\|AA DP\|AA Charge pipe and BOV\|AFE S2 Intake\|HELIX FMIC
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