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      03-12-2020, 11:11 AM   #23
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Quote:
Originally Posted by Happy Motoring View Post
So don't lift off the throttle?
I'm not aware of any no lift shift tunes for the 6MT M2...
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      03-12-2020, 11:13 AM   #24
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Quote:
Originally Posted by MZWIE View Post
Why would you shift at 5800rpm. I never shift below 6500-7000 especially if I am doing spirited driving.
There are degrees of spirited driving. There is also the characteristics of the stock N55 that mean short shifting can actually be better at keeping you in the power band.

I guess the point is that I would like to be able to drive my car how I like, and not be restricted in when I can shift to avoid the shift lag. I'm still not convinced that this isn't a software thing... see my next post.
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      03-12-2020, 11:30 AM   #25
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Thanks so much for taking a look at this SeanWRT.

Quote:
Originally Posted by SeanWRT View Post
From the log, the shift takes 1.4s to complete, from pedal lift to it 100% back on. And in it, there's 1 full sec with 50% or lower pedal angle.
Agreed.

Quote:
What does ECU do on pedal lift?
1) Throttle closure, which pretty much follows pedal input, as a direct and most effective manifold boost (MAP) control measure.

2) The throttle closure makes the backpressure to the compressor (the cold end of turbo). That's when DV comes in (log doesnt show unfortunately) and release the charge pressure (the boost in the charge pipe, or Pre Boost). To avoid mechanical failure. See there is a short time in the log (shown below) when MAP is cut but Pre boost is significantly higher until they're closer? That's what it is.

3) Wastegate fully open (to 0%) to release the pressure on the impeller.
I'm with you up to here.

Quote:
When DV's done with boost control, WG reacts to boost target (or torque target which ultimately is pedal input) with correct opening %. As said earlier, WG is a lagging measure for boost, and only a reflection of turbo shaft speed compared to boost target.
I'm not quite sure what you mean here, but if we add WGDC to the chart you posted, you can clearly see that it doesn't close to 100% until a full second after Accelerator Pedal Position, Torque Target and Throttle Angle are all at 100%... My question is very simple... Why is the Wastegate not closing to 100% for this 1 second period. As soon as it does close, the turbo spools up far more rapidly.

Quote:
A simple put - Lag is from too much off pedal time.

In this particular case, when you go back to 100% pedal, the boost is already 11.8psi off (MAP=Preboost=3.4psi, target=15.2psi). See the big boost delta area. It takes a whole lot of time (another 1.3 secs) for boost buildup to target.
But my point is that boost would build up much quicker than 1.3 seconds if only the waste gate would close. You can see the change in boost pressure rise happens suddenly once the waste gate closes, but it's a full second after you're back on the gas after a shift... And you can feel this when driving very easily.

Quote:
Revisit my conclusion - human shift is too slow, ECU has no choice but dump boost for mechanical safety. And boost takes time to recover. Hence the lag. I guess stick shift fun comes at cost LOL

Hope it makes sense.

Sean
I guess what I'm saying is that I expect some lag from a human shift being slow; it's inevitable, just as you say.

Throttle closes, DV dumps pressure and the waste gate opens all as soon as you let off the gas. Boost pressure drops dramatically and once you're back on the gas the pressure is way off target. You explained it well and it all makes sense.

What doesn't make sense to me is what happens once you're back on the gas - isn't the waste gate delayed closing behaviour making the situation far far worse (1 second more lag) than it needs to be?
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      03-13-2020, 12:08 AM   #26
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I did some further testing today to see if the waste gate delay was caused by the DME seeing the clutch position, or due to simply getting back on the gas from a 1 second lift off. To do this I conducted 2 tests:
  1. A 'no lift shift' from second to third: https://www.bootmod3.net/log?id=5e6a...0b4350057969b9
  2. Going from floored in gear, to lifting off for 1 second (no clutch) to floored again: https://www.bootmod3.net/log?id=5e6a...0b4350057969bd
Both of these cases resulted in no waste gate drop when back on the gas!

The second test was quite informative because it does show the same boost drop when you lift, but has different characteristics when you floor it again. Wastegate is pegged at 100% from only 62% pedal position and stays there until the boost target is met... as I would expect.


The 'no lift shift' felt pretty terrible; a big shock to the drivetrain, and I don't think I'll be doing that again in a hurry. Boost was held through the shift, so the waste gate never had to close, so I'm not sure how useful this test was.

The next test I plan to do is shifting up without the clutch. This is slower than with the clutch, because you have to wait for the revs to drop to match the gearbox speed, but it is pretty easy to do on an upshift. This should indicate if it's the clutch signal to the DME that is causing the waste gate delay because it doesn't seem to be present when you simply let off the gas.
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      03-13-2020, 12:20 PM   #27
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Quote:
Originally Posted by Nezil View Post
I did some further testing today to see if the waste gate delay was caused by the DME seeing the clutch position, or due to simply getting back on the gas from a 1 second lift off. To do this I conducted 2 tests:
  1. A 'no lift shift' from second to third: https://www.bootmod3.net/log?id=5e6a...0b4350057969b9
  2. Going from floored in gear, to lifting off for 1 second (no clutch) to floored again: https://www.bootmod3.net/log?id=5e6a...0b4350057969bd
Both of these cases resulted in no waste gate drop when back on the gas!

The second test was quite informative because it does show the same boost drop when you lift, but has different characteristics when you floor it again. Wastegate is pegged at 100% from only 62% pedal position and stays there until the boost target is met... as I would expect.


The 'no lift shift' felt pretty terrible; a big shock to the drivetrain, and I don't think I'll be doing that again in a hurry. Boost was held through the shift, so the waste gate never had to close, so I'm not sure how useful this test was.

The next test I plan to do is shifting up without the clutch. This is slower than with the clutch, because you have to wait for the revs to drop to match the gearbox speed, but it is pretty easy to do on an upshift. This should indicate if it's the clutch signal to the DME that is causing the waste gate delay because it doesn't seem to be present when you simply let off the gas.
I love this thread Nezil as the lag also bothers me sometimes.

When I used to have a porsche boxster I shorted the clutch switch so that the dme always thought the clutch was always engaged - this made a massive improvement to the responsiveness of the engine immediately after shifts.

A while ago I did contemplate doing the same thing with the m2, but backed off as I thought the dump valve might not open and it'd cause alot of issues. I didn't then have Bm3, but now do so logging/checking would be easier.

Still it could be worth investigating. If the dump valve was opening ok with the clutch shorted (which actually it should be as the pressure is controlled regardless of clutch position), then things like hill start and cold engine rev assistance would stop - hey, it'd be exactly like driving a car from 15 years ago (which is a good thing imo!).
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      03-13-2020, 12:23 PM   #28
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Quote:
Originally Posted by Nezil View Post
There are degrees of spirited driving. There is also the characteristics of the stock N55 that mean short shifting can actually be better at keeping you in the power band.

I guess the point is that I would like to be able to drive my car how I like, and not be restricted in when I can shift to avoid the shift lag. I'm still not convinced that this isn't a software thing... see my next post.
You have MT. Always slower than DCT. I have DCT and the sifts are very fast. Especially if a paddle them.
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      03-13-2020, 01:44 PM   #29
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Quote:
Originally Posted by MZWIE View Post
You have MT. Always slower than DCT. I have DCT and the sifts are very fast. Especially if a paddle them.
It's not about being faster than DCT, that lag just doesn't feel right.
Imagine in your DCT that there was a delay in power after shifting, you'd want to find a solution too.
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      03-13-2020, 08:24 PM   #30
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Quote:
Originally Posted by Happy Motoring View Post
It's not about being faster than DCT, that lag just doesn't feel right.
Imagine in your DCT that there was a delay in power after shifting, you'd want to find a solution too.
Yes. All 6MT owners know that weíre sacrificing shift speed over DCT and some lag due to that. What we donít expect is DME introduced additional lag for no good reason. Itís something that bothered me since day one, and I think itís something that tuners have not focused on because they often have DCT cars and are simply unaware of it.

I first started getting annoyed about it when trying to match the 0-60 times published in magazines. The additional lag between first and second makes it near impossible to achieve the 4.3s claimed, particularly stock, because we get an entire second off boost after shifts.

Itís my suspension that either BMW had custom software on journalists cars, or the journalists did no lift shifts to get their times, the latter being more likely.
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      03-13-2020, 10:11 PM   #31
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Quote:
Originally Posted by Nezil View Post
Yes. All 6MT owners know that weíre sacrificing shift speed over DCT and some lag due to that. What we donít expect is DME introduced additional lag for no good reason. Itís something that bothered me since day one, and I think itís something that tuners have not focused on because they often have DCT cars and are simply unaware of it.

I first started getting annoyed about it when trying to match the 0-60 times published in magazines. The additional lag between first and second makes it near impossible to achieve the 4.3s claimed, particularly stock, because we get an entire second off boost after shifts.

Itís my suspension that either BMW had custom software on journalists cars, or the journalists did no lift shifts to get their times, the latter being more likely.
Have you considered reaching out to any BMW engineers on social media or via email for insight? I'm generally able to find people via dedicated google searching that I can reach out to.
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      03-15-2020, 06:20 AM   #32
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Quote:
Originally Posted by Nezil View Post

But my point is that boost would build up much quicker than 1.3 seconds if only the waste gate would close. You can see the change in boost pressure rise happens suddenly once the waste gate closes, but it's a full second after you're back on the gas after a shift... And you can feel this when driving very easily.



I guess what I'm saying is that I expect some lag from a human shift being slow; it's inevitable, just as you say.

Throttle closes, DV dumps pressure and the waste gate opens all as soon as you let off the gas. Boost pressure drops dramatically and once you're back on the gas the pressure is way off target. You explained it well and it all makes sense.

What doesn't make sense to me is what happens once you're back on the gas - isn't the waste gate delayed closing behaviour making the situation far far worse (1 second more lag) than it needs to be?
Hi Nezil, noticed you updated days ago, but didn't have time for a second look at log until now.

The WG behavior does seem abnormal. As when pedal fully back on, the boost delta is big enough to warrant a 100% WG duty but it held back a little to 80%.

Has it been consistently that way?

I suspect the safety action was still being taken at that moment, if the unsettling RPM is any indication. It could be the clutch not being fully engaged or the uneven road surface (less likely as I know what log would've been like).

WG is 100% for a short time (when RPM settles) before it goes down to 80% again which is normal - when boost is close enough to target, WG% goes down to prevent from overshoot, something you can find out for yourself if you floor it off boost and from low rpm.

Please take a look from other logs, specifically at WG behavior after 100% pedal.

In the end, I'm positive 100% WG won't solve the problem with 1.4s shift...Key is still off pedal time. As you see from DCT log, the system is able to hold boost during shift and for most of the time is dealing with overboost.

Thanks

Sean
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      03-17-2020, 03:24 PM   #33
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Quote:
Originally Posted by SeanWRT View Post
Hi Nezil, noticed you updated days ago, but didn't have time for a second look at log until now.

The WG behavior does seem abnormal. As when pedal fully back on, the boost delta is big enough to warrant a 100% WG duty but it held back a little to 80%.

Has it been consistently that way?

I suspect the safety action was still being taken at that moment, if the unsettling RPM is any indication. It could be the clutch not being fully engaged or the uneven road surface (less likely as I know what log would've been like).

WG is 100% for a short time (when RPM settles) before it goes down to 80% again which is normal - when boost is close enough to target, WG% goes down to prevent from overshoot, something you can find out for yourself if you floor it off boost and from low rpm.

Please take a look from other logs, specifically at WG behavior after 100% pedal.
Always thanks to you SeanWRT, for taking the time to respond. I've been busy myself and now only find the time to respond.

First off, I'm really glad and encouraged that you can see the WG behaviour seeming to be abnormal. To answer your question... Yes, it has always been that way, every single time I shift. Stock and tuned, with and without FBO parts.

The unsettling RPM is probably clutch shudder as it re-engages, particularly 1st to 2nd or 2nd to 3rd shifts, I can do logs of 3rd to 4th pretty easily and you'll see less of it there, but the same WG behaviour; I don't think they're related. The WG delay is always and consistently exactly 1 second; it really does look suspiciously like a software thing.

I'll try to gather some more logs, but this WG behaviour is consistent for my car. One thing I'd like to try is letting of the gas, and dipping the clutch but not shifting. This should indicate if the WG behaviour is linked to the clutch signal, as I suspect.

widetyres suggests that Porsches had a similar behaviour in the past?
Quote:
In the end, I'm positive 100% WG won't solve the problem with 1.4s shift...Key is still off pedal time. As you see from DCT log, the system is able to hold boost during shift and for most of the time is dealing with overboost.
Of course. I can capture a log with a quicker shift, but I am certain it won't be different. I'm not expecting DCT performance at all, and I totally expect 6MT to be compromised in performance for that reason.

The WG closing properly should reduce the total lag down to true turbo lag, which is fine, and only what I'm trying to achieve.
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      03-18-2020, 10:58 PM   #34
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3t3p mentioned NVM UK in another post totally unrelated to this, talking about their 600 bhp big turbo N55 project. This project has interested me for some time, because I'd like to upgrade my turbo at some point, but if this DME introduced lag cannot be improved, I don't think I'll bother.

I therefore reached out to NVM to see if they'd ever heard of this lag between shifts issue affecting 6MT cars. Their response was both encouraging, alarming and disappointing:
Neil,

Yes we do have a fix for this in UK. Unfortunately remote tune is not available.

Regards

NV Motorsport UK
So, short and sweet. Encouraging because it seems like there might actually be a fix, alarming because if this is already known about, why isn't it a headline feature in tunes for the 6MT platforms, and disappointing because NVM has a fix, but cannot share it with me / us.

I've opened a support ticket with proTUNING Freaks, hopefully they'll be able to look into this.
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      03-19-2020, 10:04 PM   #35
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Just a quick update... I'm working with proTUNING Freaks on this issue. No good news yet, but I'm hopeful. At least they're being responsive and looking in to it with me.
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      03-20-2020, 01:49 AM   #36
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Quote:
Originally Posted by Nezil View Post
Just a quick update... I'm working with proTUNING Freaks on this issue. No good news yet, but I'm hopeful. At least they're being responsive and looking in to it with me.
Nice one Nezil!

It'd be super amazing if ptf sort this for 6MT
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      03-22-2020, 07:40 PM   #37
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Another update for anyone following this...

Halim @ proTUNING Freaks sent me a file that reduced the waste-gate lag by half, so a step in the right direction, and I definitely could feel the improvement! He's now sent me a new file to try which I'm hoping is further improvement, but I can't test it because it's raining heavily outside and it's difficult to get logs with DSC off in the wet!

Fortunately I live in California, so it shouldn't stay wet for long, and the forecast for tomorrow is sunny with clouds.

If this works, I don't think I'm exaggerating when I say that this could be the biggest tuning improvement to 6MT M2s since they launched. It's likely to affect all 6MT N55 cars, probably all 6MT S55 cars and maybe as much as all 6MT turbocharged BMWs!
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      03-22-2020, 09:46 PM   #38
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Quote:
Originally Posted by Nezil View Post
Another update for anyone following this...

Halim @ proTUNING Freaks sent me a file that reduced the waste-gate lag by half, so a step in the right direction, and I definitely could feel the improvement! He's now sent me a new file to try which I'm hoping is further improvement, but I can't test it because it's raining heavily outside and it's difficult to get logs with DSC off in the wet!

Fortunately I live in California, so it shouldn't stay wet for long, and the forecast for tomorrow is sunny with clouds.

If this works, I don't think I'm exaggerating when I say that this could be the biggest tuning improvement to 6MT M2s since they launched. It's likely to affect all 6MT N55 cars, probably all 6MT S55 cars and maybe as much as all 6MT turbocharged BMWs!
Awesome! As someone who was definitely buying a 6MT M2 or M2C this year before this whole coronavirus fiasco, and hopefully will after, I thank you for your efforts.
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      03-23-2020, 01:36 AM   #39
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Quote:
Originally Posted by Nezil View Post
Another update for anyone following this...

Halim @ proTUNING Freaks sent me a file that reduced the waste-gate lag by half, so a step in the right direction, and I definitely could feel the improvement! He's now sent me a new file to try which I'm hoping is further improvement, but I can't test it because it's raining heavily outside and it's difficult to get logs with DSC off in the wet!

Fortunately I live in California, so it shouldn't stay wet for long, and the forecast for tomorrow is sunny with clouds.

If this works, I don't think I'm exaggerating when I say that this could be the biggest tuning improvement to 6MT M2s since they launched. It's likely to affect all 6MT N55 cars, probably all 6MT S55 cars and maybe as much as all 6MT turbocharged BMWs!
This is amazing Nezil!

Fairplay to you for pursing this, and great to see ptf responding so quickly!
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      03-23-2020, 06:43 PM   #40
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Interesting! I don't think lag is bad, I change when I'm absolutely ragging the car on spirited drives though haha.

Glad my random ramblings about NVM have at least been of some use.
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      03-25-2020, 11:45 PM   #41
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I've posted before about experiencing the 1sec lag/delay getting back on wot and adopted the 'fix' of shifting after 6K rpm after reading it on this forum.

From some 'testing' I did 2 days ago I'm now wondering whether shift speed (ie time off throttle) with the oem engine set-up is contributing to the issue. I went for a solo country drive so was able to randomly stop on straight stretches of road, I managed to do 10 x wot shifts 1 through 4th gears (fear of instant lost licence stopped 5/6th) and varied shifting between 4 & 6K+ rpm, not once did I get the lag/delay. Traction light came on every shift into 2nd and a few into 3rd (road was intermittently slightly damp). Stock tune driving in Sport mode.

I was shifting as fast as I could with the Auto Solutions 20% SSK/Raceseng Cylinder Circuit knob & BMS clutch stop 2 shims. Previously I wasn't confident shifting as fast, I initially had a AS SSK 25% reduction and because it was a bit tight/notchy I was cautious at letting the clutch out too quickly fearing the obvious. Before that it was the oem shifter which is just so rubbery/vague compared to the AS SSK.

I'm on track next week (not cancelled as yet due to Cvirus) so will see if I can repeat the results.
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      03-26-2020, 10:15 AM   #42
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Hi all. I've got quite a bit more information, but not much of an update I'm afraid.

I have been working with Halim @proTUNING Freaks, and initially things looked good. I do have a firmware that appeared to reduce the waste gate delay, but further testing shows that this might not have been the case.

To be clear, the issue that I'm trying to fix, is the ~1.0 seconds of additional lag after a shift if you're not really 100% 'on it'. One of the things that has pissed me off about the M2 since buying it, is that if you drive it at 10/10ths, really hard, red-lining and slamming shifts, there is no question that it's fast and there are few problems. As soon as you drive it at 7/10ths, maybe shifting at 5,500 rpm, or taking just over a second for a shift, all sorts of strange and undesirable behaviour occurs.

I've said it many times already, but just to re-iterate, I'm not expecting boost to be held between shifts, I'm not expecting 6MT to be able to shift as fast as DCT, and I'm not expecting no lag at all.

In my most recent email discussion with Halim, he mentioned something very interesting. He said that the DME has a 'feature' where if you're WOT and you let off briefly, either to tap the breaks, or to shift gear, you then only need 25% pedal travel for the motor to go back into WOT state again. I assume that there is some check to make sure that you actually did go back to 100% pedal travel, but I think the purpose is to improve perceived throttle response by anticipating your intent.

Anyway, Halim's point was that if you take a long time over a shift, you may drop out of this window while you're off throttle. He therefore suggested that I try shifting quicker. As stated earlier, this goes against what I was hoping to achieve. My normal fast shift speed is pretty consistently 1.4s off the pedal, but I can do shifts consistently at about 0.7s if needed. This wouldn't be a solution in my mind, but I captured some logs this way anyway.

What I found was that if the shift is quicker, the delay before the waste gate closes is longer, by almost exactly the same amount of time. If I make my shift 0.5s shorter, the waste gate closes 0.5s later! To state this another way, the waste gate closing delay is not changed or improved at all by shifting quicker.

It seems like the waste gate behaviour is gets disrupted for a fixed period of time which starts from when you come off the pedal for any reason. Once you're back on the pedal again, the waste gate goes to about 80% and stays there until this fixed period ends before resuming regular behaviour.

In the past, I had felt that the delayed waste gate closing might be in response to the DME seeing the clutch position change. I therefore took some logs with the clutch position sensor disconnected. You need it connected to start the car, but can then disconnect before logging. The results were identical - the clutch position is not what the DME is responding to.

My theory at this point, is based on what Halim said. I think that the DME behaviour that allows the motor to go back to WOT with only 25% pedal may be the cause. This 'anticipation' behaviour puts all of the motor controls back in a WOT state very quickly, but part of this is putting the waste gate either at the same position as it was before the lift, or at a pre-determined position, rather than 100% closed. After a period of time, the DME goes back to regular control, and the waste gate acts normally again.
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Last edited by Nezil; 03-26-2020 at 10:33 AM..
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      03-26-2020, 10:30 AM   #43
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Quote:
Originally Posted by David.m View Post
I've posted before about experiencing the 1sec lag/delay getting back on wot and adopted the 'fix' of shifting after 6K rpm after reading it on this forum.

From some 'testing' I did 2 days ago I'm now wondering whether shift speed (ie time off throttle) with the oem engine set-up is contributing to the issue. I went for a solo country drive so was able to randomly stop on straight stretches of road, I managed to do 10 x wot shifts 1 through 4th gears (fear of instant lost licence stopped 5/6th) and varied shifting between 4 & 6K+ rpm, not once did I get the lag/delay. Traction light came on every shift into 2nd and a few into 3rd (road was intermittently slightly damp). Stock tune driving in Sport mode.

I was shifting as fast as I could with the Auto Solutions 20% SSK/Raceseng Cylinder Circuit knob & BMS clutch stop 2 shims. Previously I wasn't confident shifting as fast, I initially had a AS SSK 25% reduction and because it was a bit tight/notchy I was cautious at letting the clutch out too quickly fearing the obvious. Before that it was the oem shifter which is just so rubbery/vague compared to the AS SSK.

I'm on track next week (not cancelled as yet due to Cvirus) so will see if I can repeat the results.
In case you didn't read everything I just posted, there are two things that appear to happen with a quicker shift, or a shift at high revs.
  • The first is that the higher the revs are, the higher they're going to be in the next gear, and the quicker boost will build, even if the waste gate doesn't fully close.
  • The second is that if you shift quickly, the boost doesn't drop as much, so there is less boost build needed to reach target again.
So... quicker shifts and / or shifting at higher revs can 'mask' the problem, but logs show that it's 100% still there. Even the common wisdom that if you shift above 6,000 rpm the behaviour changes... logs show that there is no difference in DME behaviour; all that seems to happen is that the issue is being masked by the reasons above.

Feeling and performance are most important of course... but unfortunately only logs will tell you what is really going on I'm afraid.
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      03-28-2020, 11:55 PM   #44
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Yesterday I captured some more logs to further the investigation of this behaviour. I've decided to start posting here as well because things have gone a bit quiet from proTUNING Freaks over the last few days, and I'd appreciate more thoughts from the experts on here.

First up, is a log going from cruising with ~20% pedal travel to suddenly flooring it, to see the behaviour of the waste gate: https://www.bootmod3.net/log?id=5e7e...0b430c464721a5


I was a bit surprised to see it, but the waste gate stays fully closed when you're cruising, even though there is no boost. I assume this is because boost only builds under load, and cruising isn't load. If load suddenly came, boost would build as quick as possible because the waste gate is already closed.

This is exactly what does happen when I floor it. The waste gate stays closed until boost meets target, then it controls the boost by opening after target is reached. Everything as expected here then.

The next log is a log where I've deliberately tried to take more than 2 seconds per shift, even though I'm flooring it in each gear. The idea here is to see if the waste gate closes immediately under this condition: https://www.bootmod3.net/log?id=5e7e...0b430c46472244


This is a second, to third, to fourth shift, and as you can see, the waste gate does exactly what I'd expect. It actually closes 100% from the very moment I start to get back on the pedal, well before the torque and boost targets go back up high.
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Current Performance Mods:
CSF FMIC, ER CP, Fabspeed Cat, Aquamist WMI, GFB DV+, NGK 97506, BM3 (Stage 2 93 OTS), CDV delete, UCP, M2C/M3/M4 Strut Brace, M3/M4 Reinforcement Rings
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