[aerobod]

One thing I have noticed is the sensing for rev matching for 2nd gear is different than for 3-5. In gears 3,4 & 5 the sensing happens in the fore/aft movement into the applicable gear, in 2nd it is sensed when moving left from the 3-4 gate (as there is no rev matching into 1st). Hesitation when moving right from 2nd to 3rd could be the cause of the rev hang or increase due to the way 2nd is sensed for rev matching.

[TheoK]

Hey guys a little bit of an update. I had the dealership do a diagnostics and they sent it to BMW. BMW came back to the dealership saying its a normal characteristic of the car. They are saying its like a no lift shift function and it blips the RPM to keep the boost built on aggressive upshifts. They are also saying this was its makes it more comfortable re-engagement and that its better for performance.

Not sure if I am buying this from BMW because when I shift near redline the RPMs will shoot over redline. Really do not know what to do at this point.

[kivyee]

The dealership guys are BSing you. Majorly. Which way does the RPM go when you upshift? Down the RPM range. How does the RPM going UP make it a "more comfortable" re-engagement? That means your clutch has to take up more of a RPM differential. The blip makes sense for downshifts. Not at all for upshifts. Don't let it rest...keep bugging them.

[lazersample]

So I have a new 2019 m240 and I’ve had the exact same issue described in this thread. After getting out of break in period and doing some harder pulls, when shifting 1 > 2, the RPMs jump back up and hold too high as pull the gear lever into the 2 gate...

Wondering if there was any conclusion for those who were experiencing this issue last year?

thanks in advance

[POMFKIMOCHI]

I just got this issue yesterday (first experienced during 2-3 shift, stopped then tried 1-2 and it happened again, then went home) after months of driving with nothing changed on my part. Only thing is when I flashed with bootmod3 a couple months ago, I noticed my downshift blip window was reduced to around 1 second vs before I could coast in neutral and still get a blip 5-10 seconds later (sometimes even upshifts blips, but only after double clutching). I sent a ticket to PTF, are there still no further conclusions?

[SkyeC]

I have the same thing on my m240; bm3 stage 1 if it matters.

Thought it was just my imagination but it's happened a few times, usually on WOT 2-3 shifts, and I let up and shift like a sane person. It's enough of an increase that my head will hit the headrest!

I'm 39, manuals since 16, so I generally consider myself skilled in operating a transmission!

Definitely feels like it's trying to rev match on up shift, even though of course this is not needed.

[4Hockey4]

Originally Posted by SkyeC

I have the same thing on my m240; bm3 stage 1 if it matters.

Thought it was just my imagination but it's happened a few times, usually on WOT 2-3 shifts, and I let up and shift like a sane person. It's enough of an increase that my head will hit the headrest!

I'm 39, manuals since 16, so I generally consider myself skilled in operating a transmission!

Definitely feels like it's trying to rev match on up shift, even though of course this is not needed.

I get in Sport mode a bit, none in Sport+

[wally92]

Originally Posted by 4Hockey4

I get in Sport mode a bit, none in Sport+

I too have seen the same on my m240i, stock. Although it feels like it has been a while since I have experienced it, which may have to do with my rev-matching settings.

I put about 10,000 miles on driving mostly in DSC off, however I wanted the safety of some stability control and also like more aggressive tip-in for the throttle in Sport/Sport+. So I turned off rev matching in BimmerCode a couple years ago and would never go back.

This is under 'expert mode'...
Front Electronic Module -> 3020 -> tcm_startlock_clutch 'not active'

The only side effect that I know of is that starting the car becomes 'different'. You need to press the start button once to get into Run, and then hold it to start the car. I have put about 24,000 miles on with rev matching turned off, with mildly aggressive backroads driving, with no ill effects.

I code it back when I visit the dealer to avoid any confusion about the starting sequence.

At this point I could never go back to driving the car with rev-matching turned on. The heel-toe setup is perfect, and I bought (ordered) a manual so I could do the shifting. As much as I love it I would sell the car if I was forced back to rev-matching.

I can't say for sure that I have never seen the rev-hang without rev-match, or that I only saw it before I changed my settings, however I will keep an eye out for it and will update the thread if I see it.

[POMFKIMOCHI]

Originally Posted by jt8307

To me it appears to be related to the wastegate timing, almost as if the car is not relieving pressure fast enough during the gear change. It isn't driver error and related to a clutch/throttle timing issue because if you engaged the clutch before letting off the throttle fully, the rpm's would not momentarily decrease and then increase again. Also, you, myself, and the shop foreman were all able to reproduce it, so it is independent of driver. What also leads me to believe that it is related to boost/wastegate timing is that when you do complete a shift and stay on it when it occurs, the car is viscous when you get back on it, similar to a powershift where it maintains full boost during the shift. While this is fun and exhilarating, I can't imagine it is good for longevity of the powertrain.
~ J

I think you actually hit the nail on the head with this theory, because it just happened to me again whilst explaining to my friend, except this time, it happened on DSC OFF... which should mean there is no rev-match intervention. It's really weird though because the surge happens during the gear change and not immediately after pedal lift. Highway this time, I definitely could not have fucked up the shift because it was a simple 3-4 pull back. It was SUPER ironic because I was literally telling my passenger how if I'm in DSC OFF I'll be protected from this fuckery but, lo and behold, it went from around 6500rpms to 7500+ (literally the entire rpm gauge, was probably sitting at ignition cut). I NEED to get a log of this happening.. anyone have any video evidence ? I have yet to catch it.

[POMFKIMOCHI]

I finally captured the phenomenon in a datalog, anyone care to attempt to work out wtf is happening here? https://www.bootmod3.net/log?id=6040...0b43299f404667

[aerobod]

Originally Posted by POMFKIMOCHI

I finally captured the phenomenon in a datalog, anyone care to attempt to work out wtf is happening here? https://www.bootmod3.net/log?id=6040...0b43299f404667

Difficult to tell without having the fuel flows/open times for the injectors and a correct time scale to quantify events (time is showing 0.15 seconds from 31mph to 99mph).

[POMFKIMOCHI]

Originally Posted by aerobod

Difficult to tell without having the fuel flows/open times for the injectors and a correct time scale to quantify events (time is showing 0.15 seconds from 31mph to 99mph).

Is this my error? I have no idea how to adjust/represent those values. Very new to datalogging and tunes, thanks in advance!

[aerobod]

Originally Posted by POMFKIMOCHI

Is this my error? I have no idea how to adjust/represent those values. Very new to datalogging and tunes, thanks in advance!

It depends on the tool, but the values are all available from an ECU perspective and should be able to be calibrated, I would talk to protuningfreaks or whoever you obtained BM3 from to see what they have to say.

[POMFKIMOCHI]

Originally Posted by aerobod

It depends on the tool, but the values are all available from an ECU perspective and should be able to be calibrated, I would talk to protuningfreaks or whoever you obtained BM3 from to see what they have to say.

I see, I have already contacted them previously about this and they weren't very helpful, I have sent them the newly acquired log though but just looking to get some external opinions, taking any possible leads I can get at this point.

[Sonertial]

Has anyone got any further news on this issue?

I have been plagued by this for a while now too. Also pretty sure it came with the software update that got rev-matching working "properly" on gear skipping downshifts.

I have attached an mp3 exhaust audio of a 4th gear pull where the horrible over-rev occurs near the end of the 14 second clip.

This is with DSC OFF. i.e. no rev-matching active.

[SpencerC_6MT]

Originally Posted by makrop

I mainly seem to only notice it going from 2nd to 3rd. The rpms will hang it seems and dont drop nearly as fast as they should when letting off the gas, making for a really sloppy shift.

This is just rev hang, like the Honda boys complain about. Not sure if you can code it out with Bootmod or a similar tune, but it's definitely meant to be there from the factory. From what I understand, it occurs to protect the catalytic converter from unburnt fuel when you suddenly let off the gas. I also experience it in my '17, typically on high-RPM 2-3 and 3-4 shifts. I don't seem to notice it on 1-2 shifts or the rare 4-5, but it could just be that I unknowingly let off the gas a bit slower on those shifts.

The crucial point is, you're not getting rid of it without a tune. It's entirely intended to be there and no amount of software updates can change that. You can either change your driving style, live with it, or possibly get an ECU tune.

EDIT: Did not realize this was such an old thread, sorry

[ilanvv]

Did anyone find a fix for this, I recently just acquired a 2017 MT m240i and this happened multiple times while at WOT, even if i was in sport,sport+ and dsc off mode. Its getting quite frustrating.

[MAMSport]

I'm familiar with Honda Civic Si rev hang. Does this issue exist exclusively with manual transmission, B58 M240i, or do automatic transmissions somehow have similar issues?

[POMFKIMOCHI]

After almost 2 years of back and forth with Halim from BM3 and 6 different revisions he seems to have tuned it completely out. It was very much not rev hang as can be seen on my log posted previously because the rpms drop until the shifter is placed into a higher gear gate then the rev occurs. I am on a custom tune from him and he wouldn't elaborate on what he did to fix it but he did acknowledge it was an issue on stock as well but whenever I'd flash back to stock it wouldn't do it. Sorry I can't really help further but it is definitely resolvable with Halim. For those that are stock I found that if you fully let out the throttle then start pushing in the clutch then it wouldn't happen, it makes shifts a lot clunkier but it's better than it revving like you're flat foot shifting.

[gxr]

Heh, I just finally gave up and went back to stock because of this same issue. Doesn't happen at all on the stock tune but BM3 stage 1 was definitely an issue. They tried telling me "it's an issue with BMW's 6MT software" but somehow doesn't happen stock? I got sick of going back and forth with them.

If it helps any, I could reliably get it to happen by going WOT to the top of 3rd then trying to skip from 3rd to 5th or 6th. As soon as I moved the shifter over to the right (not even in a gate) it would do a nasty over-rev similar to what Sonertial posted.

After driving on the stage 1 tune for a month or so it also made it super easy to notice that the rev matching on downshifts is definitely different. I'm not sure what BM3 is doing to mess with it, but I'm more than certain that's the cause of the problem and honestly, between that and the throttle "responsiveness" stuff they do, it's more annoying than it's worth IMO.