[David.m]

Originally Posted by ksalih

How did you effectively remove the CDV? Did you swap in a different slave without the CDV - I think I recall seeing an e9x version that was a direct replacement. Thx!

Someone posted a video showing a diy while leaving the oem slave in situ and I followed that procedure, was really easy. My first attempt with the clutch bleed failed, the clutch chamber inside the master cylinder is obviously very small, 2nd effort worked and has been great since. Link to a post I made after doing it.
https://f87.bimmerpost.com/forums/sh...7&postcount=50

[PackPride85]

Originally Posted by chris719

Yep, I know that, but what's the difference here between N55 and S55?

Don't know other than some function built into the N55 DME that the S55 does not use.

[jbragg1978]

Just read the whole of this thread from start to finish.

Great work from all! This is what these forums are all about.

Is everyone still happy with this issue now been largely resolved with v5.9 of BM3 without needing anything more radical?

On a 6MT car with BM3 stage 2 (v5.9), CSF FMIC, forge and boost pipes, pure inlet, would you guys still recommend doing the following please?

* GFV DV+? Seems to make a positive difference albeit not on between gear lags. Bee Pee makes a good point about durability of the original and potential leaks.

* CDV delete? Consensus seems to be to swap out for the E90 slave. 21526785964. Is this still worthwhile for overall drivability/smoothness, given the v5.9 BM3 seems to fix the 6MT load issues.

* 97506 spark plugs? Versus the OEM ones. I know this is slightly off topic and makes no difference to the between shift lags…

THANK YOU!

[AmuroRay]

Originally Posted by jbragg1978

Just read the whole of this thread from start to finish.

Great work from all! This is what these forums are all about.

Is everyone still happy with this issue now been largely resolved with v5.9 of BM3 without needing anything more radical?

On a 6MT car with BM3 stage 2 (v5.9), CSF FMIC, forge and boost pipes, pure inlet, would you guys still recommend doing the following please?

* GFV DV+? Seems to make a positive difference albeit not on between gear lags. Bee Pee makes a good point about durability of the original and potential leaks.

* CDV delete? Consensus seems to be to swap out for the E90 slave. 21526785964. Is this still worthwhile for overall drivability/smoothness, given the v5.9 BM3 seems to fix the 6MT load issues.

* 97506 spark plugs? Versus the OEM ones. I know this is slightly off topic and makes no difference to the between shift lags…

THANK YOU!

I would go with the TurboSmart VR11 (easier install, claimed better performance)
I would still do the CDV delete
Stick with OEM spark plugs, just change them more frequently
Update to the newest version of the BM3 tune.

[jbragg1978]

Thank you, AmuroRay. Much appreciated.

Does anyone have any experience of the Turbosmart VR11 versus a GFB DV+ please, in terms of either install, performance or durability? Thank you

[widetyres]

Originally Posted by jbragg1978

Thank you, AmuroRay. Much appreciated.

Does anyone have any experience of the Turbosmart VR11 versus a GFB DV+ please, in terms of either install, performance or durability? Thank you

Re the DV, can't comment 1st hand as I have only just ordered the turbosmart, however, the turbosmart is probably the better option as it's a complete and direct swap out part, rather than the DV+ that needs some work off the car to assemble using some of the OEM DV.

Re plugs, I would personally consider going one step colder on stage 2; on a 32C evening in the UK, my Stage 2 car logged 364bhp on the dyno - pretty disappointing and the guy was quite baffled. By UK standards though, it was a hot day and likely impacted. I did some checks afterwards, all seemed fine but I swapped out the the plugs as really the only thing I could think of that might benefit. Another dyno run a few weeks later and I hit 431bhp. It was a cooler day (21C), and that would definitely have benefited but IMO the plugs helped.

[6speed_M2]

https://youtube.com/shorts/vXf-9-gwgDM?feature=share

It's not about any mods. Whether my car was bone stock or modified I never had lag inbetween shifts unless I shifted it incorrectly. You can't shift it like a NA car. You need to be quick but not do it too powerfully. Speed is also a factor.

This video is one instance of someone other than myself who shifts the car the way I do.

[David.m]

Originally Posted by jbragg1978

* CDV delete? Consensus seems to be to swap out for the E90 slave. 21526785964. Is this still worthwhile for overall drivability/smoothness, given the v5.9 BM3 seems to fix the 6MT load issues.

THANK YOU!

I would suggest that now it is known how simple & easy it is to remove the CDV while leaving the oem slave in-situ there really is no point doing this any other way. If you later wanted it would be similarly very easy to re-install the CDV though I can't imagine anyone would.
Whatever tune/other mods you have I found removing the CDV made a dramatic improvement to 1-2 shifts especially if going a little hard, the improvements while there for other shifts is imo not as significant.
https://f87.bimmerpost.com/forums/sh...7&postcount=50

[3t3p]

Forgot about this until an on ramp today, sucks, feels like forever between shifts

[Dasnub]

Originally Posted by 6speed_M2

https://youtube.com/shorts/vXf-9-gwgDM?feature=share

It's not about any mods. Whether my car was bone stock or modified I never had lag inbetween shifts unless I shifted it incorrectly. You can't shift it like a NA car. You need to be quick but not do it too powerfully. Speed is also a factor.

This video is one instance of someone other than myself who shifts the car the way I do.

Yes, everyone here is just a terrible shifter and if they would just do it more like you…

There is documented physical log data of this issue. It’s in the thread. It’s the reason companies like BM3 have spent time and resources to develop a fix. What you’re referring to is the “fix” many believe existed early on, which was to shift after 6k rpm. But it has long since been determined that doing that only masked the root cause- it didn’t eliminate it.

[Wolfman’s Brother]

I have also noticed differences in this issue depending on how I shift.

It’s not a matter of wrong or right, but clutch & throttle application do appear to have an impact on the matter in my experience.

[widetyres]

Originally Posted by Wolfman’s Brother

I have also noticed differences in this issue depending on how I shift.

It’s not a matter of wrong or right, but clutch & throttle application do appear to have an impact on the matter in my experience.

That is the case to some level. The root cause seemed to be the requested load breaching a boundary value when the clutch wasn't fully up. The ecu then backs off for a second or two before allowing the load target to rise again.

So, if you let the clutch come up all the way up before nailing the throttle, you'll have much less of an issue. However, that's a slow way to drive IMO.

Honestly if you have a 6mt, bm3 is pretty much mandatory - shame it wasn't an option from the factory! Lol!

[6speed_M2]

Originally Posted by Wolfman's Brother

I have also noticed differences in this issue depending on how I shift.

It's not a matter of wrong or right, but clutch & throttle application do appear to have an impact on the matter in my experience.

Dasnub gphung this is a +1 to my original point.

You can take the horse to the river but you can't make it drink the water.

Let me know how the "fix" goes

[PackPride85]

I was a test mule for bm3 on the fix a while back. I remember them saying there was some function present in N55 DMEs related to shifting and load targets that was not present in the S55. It was very noticeable during testing when that function was removed and the lag disappeared. It has nothing to do with "the right way to shift".

[Wolfman’s Brother]

Originally Posted by PackPride85

I was a test mule for bm3 on the fix a while back. I remember them saying there was some function present in N55 DMEs related to shifting and load targets that was not present in the S55. It was very noticeable during testing when that function was removed and the lag disappeared. It has nothing to do with "the right way to shift".

I’m using the updated BM3 and still notice lag between shifts in certain cases. Don’t gaslight me brah. I’ll tell PC principal.

[PackPride85]

Originally Posted by WolfmanÂ’s Brother

I’m using the updated BM3 and still notice lag between shifts in certain cases. Don’t gaslight me brah. I’ll tell PC principal.

It will still dump boost at certain part throttle
Load requests but it should work 100% at WOT

[AmuroRay]

Originally Posted by PackPride85

It will still dump boost at certain part throttle
Load requests but it should work 100% at WOT

I don’t have this issue at all, so I can’t comment - but does this still happen after upgrading your DV?

Mine throws a shadow code for Divertervalve shut, which I assume means it’s holding boost until the next shift.

[widetyres]

Originally Posted by AmuroRay

I don’t have this issue at all, so I can’t comment - but does this still happen after upgrading your DV?

Mine throws a shadow code for Divertervalve shut, which I assume means it’s holding boost until the next shift.

You have an m235? I think the this issue was only on f8x.

Dv makes little difference to this - somewhere I did sone log comparisons.

[i531m]

My manual f20 m135i does this too, wgdc isnt always at 100 percent after the shift

im running mhd stage 2+ im sure it was less of a problem at stage 1 and stage 2

[Dasnub]

Originally Posted by widetyres

You have an m235? I think the this issue was only on f8x.

Dv makes little difference to this - somewhere I did sone log comparisons.

My prior M235i never did this. It’s what made it so incredibly noticeable coming to the M2.

[JoanLluch]

Originally Posted by PackPride85

I was a test mule for bm3 on the fix a while back. I remember them saying there was some function present in N55 DMEs related to shifting and load targets that was not present in the S55. It was very noticeable during testing when that function was removed and the lag disappeared. It has nothing to do with "the right way to shift".

I recently purchased an used stock M2 Comp 6MT, with very little milage, and immediately noticed this issue. I found this thread and read it all.

I appreciate all the time you and others have dedicated with tuners to help solve this issue, and I'm glad they finally acknowledged it and fixed it. My stock car power lags during upshifts definitely feel annoying, so I am now determined to apply a tune to it.

I just don't know what tune I need to ask for. I don't really want more power or torque (well, maybe just improving torque at high rpm like the M2 CS, but that's is) but I definitely want the upshift power lag removed

Do all BM3 tunes already incorporate the fix as of today?. Any information is appreciated

(Sorry for my English)

[JoanLluch]

Just as a follow up question regarding this issue and for additional thoughts: what conclusions we arrived in terms of the actual conditions that make the ECU software to do this?

I mean, is it actually only related to shifts, or will the power gap also happen if you just fully release the throttle, then push it again quickly (in a matter of say only 1 second as opposed to more than say 4 or 5) but without touching the clutch or changing gear?

I'm asking that becaue if it is ONLY related to shifts, maybe we could just trick the system by disconnecting the clutch sensor or the gear position sensor, or both?

Does the above make sense to any of the members that were involved on fixing this?