[chris the man]

Hi all, thank you for looking at this thread. Of the hundreds of threads I have scoured and bumped with a similar issue, we have had no luck.

My dads car, 2008 335i is having this issue.

Stumbling RPM's at cold start and at idle after being warmed up.

Recent services. less then 12k miles ago.
new spark plugs
oil change
new injectors
oil stand gasket
waterpump etc...

More then 12k miles ago.
new hpfp fuel pump

Cold Start. - Starts up instantly every time "no delay or lag in startup". On cold start it will stumble after a couple minutes between 500-800rpm. the car will feel shaky and feeling of misfires seem present

Warm Start. - Starts up instantly, yet at idle resting you can slightly feel shakes or misfires. Not as aggressive as cold start and it does not stumble as much. But slight misses feel present.

The car has been brought in 2 times last week. Injectors and Fuel pumps seemed to be just fine. Spark Plugs were changed just for precaution.

Has anyone else had this problem, been able to fix it, or experience anything like it? The car is never driven hard. Any help is much appreciated.

[drumminmike]

I think i have a similar problem. Here's what's been happening.

March/April '14 (~70K miles): Car begins misfiring intermittently when cruising at highway speeds (80ish, i cruise fast). Frequency of misfires increase until the engine starts shutting down cylinders. Would happen once in a 40 mile trip, within the last 10 miles. I'd pull over and restart car, and drive away with no problems. Went on for about 2 weeks, progressing to 2 or 3 restarts per trip...then wouldn't run at all without misfiring. Took it to an indy shop cause i thought it was something severe, and realized spark plugs and coils were never changed. Indy shop changed bank 1 coils and problem went away...for 2 days. Ran worse than before, so i changed bank 2 coils and all 6 plugs at the same time. I noticed some oil in the spark plug well (on top of plug by coil boot) in cyl 3, and slightly heavier in cyl 4....both cyl 3 and 4 were dark and wet when i pulled them out.

after 2 weeks, ran without having to restart....but now i had intermittent misfiring at idle when cold or hot.

August: Misfiring to the point of having to restart again in last 10 miles of my 40 mile commute...but only on REALLY humid days....also rough start on humid days. dry days, no problem starting/shutting down cylinders....but had idle issues.

Sept (~76k miles): I noticed a slight rattle in the engine bay starting back in Jan/Feb timeframe, but it was slight and i never did anything about it. It progressed to the point where i thought it was wastegate rattle so i took the car in to the dealership to take advantage of the turbo warranty. turns out there was something in my exhaust stuck between the cats and resonators...didnt pay the 400 for them to evaluate further (125 was enough). Dealer also told me the valve cover gasket was leaking and needed to be replaced. 2 weeks later, disconnected exhaust line at the flanges after post-cat O2 sensors and turned the whole exhaust up on end....dumped about a full CUP of mostly black/carbon colored metal chards/powder and some small honeycomb chunks.

No more rattle, and misfiring COMPLETELY gone (at speed and idle) for 2 weeks....thought i had fixed the problem.


Oct - Now (~84K miles): 40 mi trip means restarting 2/3 times on average. Cold starts are HORRIBLE for the first 2-5 minutes. stumbling idle, where if not gassing it, it'll shut off. and when first starting, a loud whistling sound with VERY reduced power...with power returning instantly and dramatically as soon as the whistling stops (within 1st minute). And an occasional quick metallic screech (1 sec or less) on a cold start. Warm days, and only the misfiring to deal with....no loss of power, no metallic sounds...simple restart is all it takes after 2-3 minutes of driving. I pulled the engine cover and the trough where the spark plug wells/injectors lie is FULL of oil. on a breezy day, can see the occasional waft of a white smoke come over the hood from around the front passenger wheel well. only getting 22 mpg avg hwy now, used to get 27-29...i can smell fuel when idling.


Finally bought a BT cable and pulled codes for misfiring and post catalyst fuel trim system too lean on bank 1...also bought the Haynes manual. Seems like the leaking VCG can impact a lot.


My thoughts....

I realize I've let things go to the point where I probably have a couple problems that need to be fixed....the symptoms aren't helping with the troubleshooting. Misfiring at idle, misfiring at speed, fuel trim reading lean but running rich, leaking VCG.

1) VCG needs to be replaced immediately (just arrived). Probably contributing to idle issues. also, the oil leaking into the spark plug wells could be shorting out/impacting ignition.

2) Oil is most likely running onto the other sensors below...so need to start looking at them all when i replace the VCG. VANOS Solenoids, Eccentric Sensor, Cam Position Sensor, Knock Sensors, etc.

3) Need to look into new coils/plugs based on what i see (haven't pulled those)

4) Need to look into replacing injectors (based on condition of plugs). condition).


PLEASE HELP!!! i just want my car back...living the misery, reminiscing of the good times!

[BashShah]

Oil stand gasket - did you mean Oil Filter Housing Gasket (OFHG)?

Were all the injector replaced?
Were the coils replaced as well?

Most important questions:
Who did the work?
Where the injectors OEM? Did the code in the new injectors?
And when is the last time you had a Walnut Blast?
How many k on you car right now?

Agreed, oil leaks can cause issues....but mid fires ate predominantly either fuel, air and spark relates. Hence walnut blast before anything else....I am no expert, but valve cover gasket think will cause other issues.

DN

[chris the man]

Great write up above me.

I do not think my father is experiencing the same issues as far as the car dying on him.

however it seems a lot of them are about the same!

[David1]

If the passages in the valve cover are clogged it will never idle right.

[chris the man]

Originally Posted by DarkNemesis

Oil stand gasket - did you mean Oil Filter Housing Gasket (OFHG)?

Were all the injector replaced?
Were the coils replaced as well?

Most important questions:
Who did the work?
Where the injectors OEM? Did the code in the new injectors?
And when is the last time you had a Walnut Blast?
How many k on you car right now?

Agreed, oil leaks can cause issues....but mid fires ate predominantly either fuel, air and spark relates. Hence walnut blast before anything else....I am no expert, but valve cover gasket think will cause other issues.

DN

DN, thank you!

Yes OFHG

All Injectors replaced/ tested and not leaking
BMW Corp
OEM v7 Injectors
Walnut blast can not be confirmed
His has about the same as mine 77k


I am hesitant about having him do the walnut, so many never seem to have relieved symptoms after doing the walnut. Im not too sure.

Still no answer to these problems.

[BashShah]

Be honest with you, you literally changed everythingv that should have been replaced last.
The only thing left is a wallnut blast.
But in instead of a walnut blast, why don't you pay an hour diagnostic and ask dealer or reputable shop to do a borescope. They will give you picture of what your intake ports look like,, with our doing them.

Walnut blast is generally at 50k.
So you may be really over due.

Wait a min, if the did the injectors, chances are they removed the intake port. So ask them, how did the ports look?


DN

[theweebabySeamus]

Bad coil?

[David1]

Originally Posted by DarkNemesis

Be honest with you, you literally changed everythingv that should have been replaced last.
The only thing left is a wallnut blast.
But in instead of a walnut blast, why don't you pay an hour diagnostic and ask dealer or reputable shop to do a borescope. They will give you picture of what your intake ports look like,, with our doing them.

Walnut blast is generally at 50k.
So you may be really over due.

Wait a min, if the did the injectors, chances are they removed the intake port. So ask them, how did the ports look?


DN

You don't touch the intake to do injectors.

[BashShah]

Then get a cheap borescope done..
Harbor Freight sell the tool for 69.
Get one with a led at the end.

DN

[litxus]

Originally Posted by theweebabySeamus

Bad coil?

+1, I didn't see coils mentioned anywhere. That would be next and easiest thing to do.

[BashShah]

Originally Posted by litxus

+1, I didn't see coils mentioned anywhere. That would be next and easiest thing to do.

1+ agreed you did not mention whether coils were replaced.
but still borescope the intrake ports to see how bad they are.

DN

[AndyW]

+1 on coils. I just did my sparkplugs and coils today on 2008 BMW 335i @100k and didn't get a couple of the coils connected tightly enough at first. Really rough idle on start. Stumbled, then stalled. Once all the coil connectors were reseated and verified tight...ran fine.

[chris the man]

Ok Coils seems to be the next step?

I figured my coils would throw a code or that the shop would be able to figure this out.

I am almost certain that coils were done about 12k miles ago

[chris the man]

Infact I am certain that they moved coils around when they just put new plugs in to test for coils.

but maybe this is not enough?

I think the Walnut Blast needs to be done

[AndyW]

When I did my coils I was paranoid about all the wires...if you just had a bunch of coil swapping I imagine a wiring fault could do the same thing. Then again, I also think something like that should throw a code. Walnut blast seems like a long shot...you have to have VERY gunked up intakes to cause rough idle I think. I did mine at @90k and they were dirty but not affecting idle, just causing little coughs on hard acceleration.

[iseck1]

After weeks of troubleshooting my rough idle E93 N54 I managed to solve mine. Tried everything discussed on these threads including walnut blasting the intakes, coils, cleaning electrical connectors, etc. and nothing worked. As a last resort I decided to put back the old spark plugs and voila - car runs good as new much to my surprise. Here's what I learned through the process that I thought i'd share with the forum in case it can help others. I had a bit of a rough idle a few weeks ago for which I started with new plugs from Amazon. The plugs were new OEM BMW BOSCH 4 electrode plugs and were exactly the same part number as what was in the car - even the stamping on the side was exactly the same including the "made in germany" part. There was no reason to suspect any issues with these plugs. During the change I also added a catch can and replaced a spark plug heat shield tube on #3 cylinder which had what appeared to be corrosion on it i.e. crusty green deposits. What I later learned is that corrosion is linked to spark arcing through the coil insulator to ground through the spark plug heat shield. Not all BMW's use this heat shield but it appears to be common on Turbo cars - down side to them is that they provide a good ground very close to the coil stem which can allow the spark to jump out. Once it starts the insulator deteriorates and issue gets worse. The corrosion is ionized air on the aluminum sleeve. It also deposits on the coil stem so keep a watch for these and clean (or preferably replace) these coils as needed. I suspect this was the initial reason for my rough idle but by putting in new plugs I managed to move the problem and cause weeks of headaches trying to troubleshoot. Now back to the plugs - after close inspection of the new plugs the only physical difference appears to be the gapping of the 4 electrodes. One or two electrodes on the new plugs appear to be closer to the center pin than the old ones. Remember - these are factory gapped plugs and not intended to be re-gapped by the user. I figured the larger gaps was wear on my old plugs and decided not to address it on the new ones. After about 500Km of horrible idling and lots of troubleshooting I swapped back to the old plugs as a last resort. I examined the new ones and found the ones with the small gaps had burn marks only one side of the porcelain insulator. That a sign that three other electrodes were likely not firing. All that to say - I believe short of an internal issue with the new plug (i.e. manufacturing defect) the root cause is the smaller gap on some electrodes causing an insufficient spark for proper detonation especially on idle. That likely explains why the computer does not detect a fault and why certain conditions like load from the AC compressor or engine/ambient temperature vary the symptoms. Since switching back to the old plugs the car is running perfect. If I find some time I plan to pull the old plugs again and measure the gaps then regap the new plugs somehow to match and try them again. If that works then this will tell for certain the gap is the root cause and not a plug manufacturing defect. Another key lesson here is to pay close attention to the details and part conditions. You could replace all coils, plugs, injectors and hope for the best but in my case that would have addressed the arcing coil issue and not the faulty plug gap. I would have thrown out lots of good parts and money in the process and I hate doing that because you never get to actual root cause and you waste lots of money. If the rough idle returns, I would keep a close eye the coil stems and plug heatshields. If it happened to one, it's likely going to happen to one of the other 5 and it will leave a crusty deposit as a telltale sign. Will also need to be much more careful with spark plugs - I might try NGK's as I'm told some newer BMW's come with those from factory now. Check the gaps! Hope this helps in case you are dealing with the same issues.

[BashShah]

Just an FYI.
Did you know that BMW dumped Bosch coils and went with Delphi brand.
Some nodded members here have tried them and another brand that BMW is trying on some models is Edor brand.

E90 is notorious for not logging miss fires. Slight stumbles and rough idle issues.
Bmw has changed from Bosch to Delphi because of this reason.

[thormessiah]

How was this issue resolved? I'm getting the same thing on my 08 BMW 335i.

[vympel777]

Well its happening on my x5 2015 n55. Gonna step by a dealer and try new sparks as mine are due to 60k miles. From what i noticed its happening a lot and bmw not that prompt to warn you about the codes. I have rough idle at start up but no codes car seems to run a bit jeeky. Had an issue with failing water pump on my old x5 e70 and also no codes ! Thanks to fellow forum members that pointed me in the right direction i thought my fan was failing - that's what i was told in my local repair shop lol But hey after all much better rrability than audi

[Salzamani]

Originally Posted by iseck1

After weeks of troubleshooting my rough idle E93 N54 I managed to solve mine. Tried everything discussed on these threads including walnut blasting the intakes, coils, cleaning electrical connectors, etc. and nothing worked. As a last resort I decided to put back the old spark plugs and voila - car runs good as new much to my surprise. Here's what I learned through the process that I thought i'd share with the forum in case it can help others. I had a bit of a rough idle a few weeks ago for which I started with new plugs from Amazon. The plugs were new OEM BMW BOSCH 4 electrode plugs and were exactly the same part number as what was in the car - even the stamping on the side was exactly the same including the "made in germany" part. There was no reason to suspect any issues with these plugs. During the change I also added a catch can and replaced a spark plug heat shield tube on #3 cylinder which had what appeared to be corrosion on it i.e. crusty green deposits. What I later learned is that corrosion is linked to spark arcing through the coil insulator to ground through the spark plug heat shield. Not all BMW's use this heat shield but it appears to be common on Turbo cars - down side to them is that they provide a good ground very close to the coil stem which can allow the spark to jump out. Once it starts the insulator deteriorates and issue gets worse. The corrosion is ionized air on the aluminum sleeve. It also deposits on the coil stem so keep a watch for these and clean (or preferably replace) these coils as needed. I suspect this was the initial reason for my rough idle but by putting in new plugs I managed to move the problem and cause weeks of headaches trying to troubleshoot. Now back to the plugs - after close inspection of the new plugs the only physical difference appears to be the gapping of the 4 electrodes. One or two electrodes on the new plugs appear to be closer to the center pin than the old ones. Remember - these are factory gapped plugs and not intended to be re-gapped by the user. I figured the larger gaps was wear on my old plugs and decided not to address it on the new ones. After about 500Km of horrible idling and lots of troubleshooting I swapped back to the old plugs as a last resort. I examined the new ones and found the ones with the small gaps had burn marks only one side of the porcelain insulator. That a sign that three other electrodes were likely not firing. All that to say - I believe short of an internal issue with the new plug (i.e. manufacturing defect) the root cause is the smaller gap on some electrodes causing an insufficient spark for proper detonation especially on idle. That likely explains why the computer does not detect a fault and why certain conditions like load from the AC compressor or engine/ambient temperature vary the symptoms. Since switching back to the old plugs the car is running perfect. If I find some time I plan to pull the old plugs again and measure the gaps then regap the new plugs somehow to match and try them again. If that works then this will tell for certain the gap is the root cause and not a plug manufacturing defect. Another key lesson here is to pay close attention to the details and part conditions. You could replace all coils, plugs, injectors and hope for the best but in my case that would have addressed the arcing coil issue and not the faulty plug gap. I would have thrown out lots of good parts and money in the process and I hate doing that because you never get to actual root cause and you waste lots of money. If the rough idle returns, I would keep a close eye the coil stems and plug heatshields. If it happened to one, it's likely going to happen to one of the other 5 and it will leave a crusty deposit as a telltale sign. Will also need to be much more careful with spark plugs - I might try NGK's as I'm told some newer BMW's come with those from factory now. Check the gaps! Hope this helps in case you are dealing with the same issues.

I had a similar experience. I had original BMW brand plugs with 65k miles in my 07 335i and after switching to Bosch equivalent model spark plugs the rough idle started. I also noticed the smaller gap on the new Bosch plugs but figured since they are not suppose to be regapped to just leave them that way. I had nothing but rough idle issues. Suspecting that the Bosch brand were possibly inferior plugs I decided to order a fresh set of the BMW brand version of the same plugs just like the original set that I had initially taken out. Incidentally they too looked like they had a tighter gap than the original 65k BMW plugs and I too just figured that was likely to be just normal wear. As far as how the new BMW brand plugs are performing on idle well they too cause a rough idle. Although not as bad as the Bosch brand yet not as good as the original 65k miles BMW plugs. After reading your post I now am suspecting the gap could have been the culprit all along. You mentioned you we’re gonna try regapping your new plugs, did you ever try that and if so what were your results?

[Salzamani]

Just to update; I pulled out the new BMW branded Bosch 3 prong plugs and gapped them to .035in/.889mm which is about what the original 65k mile plugs were. I realize that these plugs come pre-gapped and don’t require it but I couldn’t help myself. Popped them back in and now the car runs perfect. Rough surging fluctuating idle is gone. I don’t get it why does this N54 prefer a wider gap in the plug in order to idle smooth. Any theories?

I also want to point out that spark plug number 1 is black on the tip where the electrode pin is. Black like carbon build up with a little bit of oil around the threads and the tip does smell a bit like gas. I had noticed this issue with spark plug number 1 even 6 months earlier which is why I decided to do the valve cover gasket 4 months ago. So why after the VC gasket change is this spark plug number 1 still turning black? Can anyone chime in with any theories?