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M2 Technical Topics > Mechanical Maintenance: Break-in | Oil & Fluids | Servicing | TSB | Recalls > WOT vibration above 4krpm

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      12-08-2018, 04:03 AM   #45
M Fifty
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Is there any chance that the traction control is getting confused? WOT at 3-4k rpm sounds like a good bet for loss of traction.

In the meantime, drive to stay away from the vibration until there's an effective diagnosis and cure.
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      12-09-2018, 09:30 PM   #46
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It’s not TC related.

I’m starting to think it’s the exhaust. The vibration seems worse when I’m WOT 4-5k RPM in Sport vs Comfort.

Let me know what you guys think when you try it.
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      12-10-2018, 07:43 AM   #47
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Noting the temperature in DC is below freezing atm, how about axle tramp? Also, where are you able to drive it at WOT at that engine rpm???
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      12-10-2018, 08:08 AM   #48
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Quote:
Originally Posted by M Fifty View Post
Noting the temperature in DC is below freezing atm, how about axle tramp? Also, where are you able to drive it at WOT at that engine rpm???
It’s not a traction issue.

You can be in third and modulate the revs between 4-5k to get the vibration even with partial throttle. Doesn’t necessarily need to be WOT.
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      12-11-2018, 09:17 AM   #49
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Sounds to me like a possible tuning issue under high load and heavy boost. The M2 has the same engine as my M235 6mt but with just a factory tune that add and extra 20whp and 30wtq. The M2 makes around 2psi more than my M235 under normal full throttle driving and around 4psi during over boost. I have been running the Dinan Sport on my M235 which can add 2 to 4 psi depending on setting. During acceleration runs in 3rd and 4th, I can occasionally feel vibrations in the 3k to 5k range, especially if it's warmer out (75+) and the more is heat soaked. If I go back to stock boost, the problem largely goes away. The vibration is more apparent in the 4psi setting.

I attributed the vibrations to the DME adjusting various parameters to quell with perceived and/or real detonation. The vibration is a side effect of this response. It's well known that the M2 can heat soak quickly in warmer temps and/or heat soak and the DME can reduce power as a result, more so than the M235. This can lead to fairly large differences in power and inconsist acceleration.

I would do the following to evaluate the issue:

Note the air temp when this happens.

Does the car feel a little less powerful when it happens?

Note if the motor is really heat soaked (if you've been sitting traffic and then hammer it)

Try running the highest octane available

If you're going full or moderate throttle, try using the ideal gear (i.e. if you're at 70mph, use 3rd, not 4th)


This vibration could very likely be a natural thing for the N55 M2, especially if no codes are being thrown. If it was a mechanical issue, I would think the issue would be happening consistently.
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      12-11-2018, 09:28 AM   #50
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I’ve noticed this issue in summer and winter temps (no heat soak) with 93-100 octane.

If my exhaust thought pans out, I wonder if it’s just some kind of resonance as the exhaust has broken in over time.
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      12-16-2018, 12:47 PM   #51
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Nah it's definitely a chassis vibration, note tune related. Car still pulls like a freight train. I really do think it is resonance because there is no bushing between the hard mount of the DP to the transmission.
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      12-16-2018, 12:56 PM   #52
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Quote:
Originally Posted by stefan View Post
Nah it's definitely a chassis vibration, note tune related. Car still pulls like a freight train. I really do think it is resonance because there is no bushing between the hard mount of the DP to the transmission.
My car is at the dealer right now looking into this and a couple other things. I’m curious your feedback on if the vibration seems worse when you’re in Sport vs Comfort?
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      12-17-2018, 11:40 AM   #53
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Quote:
Originally Posted by stefan View Post
Nah it's definitely a chassis vibration, note tune related. Car still pulls like a freight train. I really do think it is resonance because there is no bushing between the hard mount of the DP to the transmission.
Noting that the engine and transmission are bolted together and rubber mounted, as is the rest of the exhaust (with a flexible section right next to the Cat), how would the lack of a rubber mount between the cat and the transmission lead to vibration being transferred to the chassis? The mounts would have to be fubar'd.

Something might be vibrating on the chassis, but that would suggest either it's loose, or it's touching the exhaust.
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      12-21-2018, 12:31 PM   #54
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Quote:
Originally Posted by ZM2 View Post
My car is at the dealer right now looking into this and a couple other things. I’m curious your feedback on if the vibration seems worse when you’re in Sport vs Comfort?
It's more prevalent in sport, maybe because of boost pressures?
Quote:
Originally Posted by M Fifty View Post
Noting that the engine and transmission are bolted together and rubber mounted, as is the rest of the exhaust (with a flexible section right next to the Cat), how would the lack of a rubber mount between the cat and the transmission lead to vibration being transferred to the chassis? The mounts would have to be fubar'd.

Something might be vibrating on the chassis, but that would suggest either it's loose, or it's touching the exhaust.
Guess so. Though it may be creating NVH at the downpipe itself resonating through the chassis.
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      12-30-2018, 04:42 PM   #55
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The dealer has had no luck tracking this down.

I'm trying a BM3 tune at the moment, and there was no change to the vibration--still there.

Apart from trying a different downpipe at some point, not sure where this will end up.
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      01-12-2019, 09:57 PM   #56
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m235i owner here, I also get this occasionally and had it checked by my shop. They said everything is perfect but mentioned that some mounts/bushings are unusually soft in the car that could be causing too much deflection and flex. We were able to duplicate it several times and he also said if it were truly a problem then you would have performance issues and the problem would get worse over time. Neither have happened to me so it is what it is i guess.
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      03-10-2019, 10:47 PM   #57
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Following up, it ended up being the differential. The dealer changed it and the vibration is gone.
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      03-12-2019, 03:43 PM   #58
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Useful to know. And a relief I'm guessing.
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      03-12-2019, 04:53 PM   #59
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Yeah, my race shop said they don’t see many issues with the M2/3/4 diffs. Not sure what was up with mine.
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      11-28-2019, 08:01 PM   #60
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Been complaining about drivetrain vibration between 3-4.5k since new. Dealership replaced final drive bushings. Vibration finally gone. Long time coming. Hope this helps.
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      11-30-2019, 04:18 PM   #61
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Ive had a similar problem in the past and a road force balance fixed it.
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      11-30-2019, 10:16 PM   #62
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Shop foreman put new wheels and tires on. Vibration was still present at WOT 3rd and 4th. 33k on the clock. Always bothered me.
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      12-01-2019, 10:21 AM   #63
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Quote:
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Shop foreman put new wheels and tires on. Vibration was still present at WOT 3rd and 4th. 33k on the clock. Always bothered me.
Same in my case.
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      12-18-2019, 07:51 PM   #64
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Experiencing this same issue myself! Relieved to hear there's a fix. Can anyone recommend a good dealer in the DC area? I just moved here recently. Thanks!
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      12-18-2019, 10:22 PM   #65
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Experiencing this same issue myself! Relieved to hear there's a fix. Can anyone recommend a good dealer in the DC area? I just moved here recently. Thanks!
BMW Silver Spring is pretty mod/track friendly if you ever go down that path.
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      12-18-2019, 10:30 PM   #66
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Quote:
Originally Posted by ZM2 View Post
Quote:
Originally Posted by Imperial328i View Post
Experiencing this same issue myself! Relieved to hear there's a fix. Can anyone recommend a good dealer in the DC area? I just moved here recently. Thanks!
BMW Silver Spring is pretty mod/track friendly if you ever go down that path.
Thanks for the reply. Currently no mod plans. I just want a service team who will take me seriously when I say that something like this is going on. Passport said oh you just have cupped tires. I have since determined that is not the cause. I've been an aircraft mechanic for almost a decade. I'm not just some guy off the street.
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