DCT kickdown behavior: S and D modes target different gears at same speed

[ZKing1208]

Originally Posted by mkoesel

Ok, so I took a longer route into work and was able to do a little testing. Here's what I found:

1. The behavior has definitely changed from the original software.
2. I agree it goes to the second lowest gear in S mode now.
   1. If, after using kick down in S mode, I try to immediately downshift to the true lowest gear, the shift is rejected
   2. If I hold speed constant from there and wait for some time to pass, the shift is still rejected
   3. If I let off the throttle slightly, the shift is finally accepted
3. I agree it is more aggressive in D mode, grabbing the lowest gear available
4. The guy in the Chevy Cruise who happened to be on the same route probably thinks I am a douchebag maniac.

This is all preliminary, but accurate to the best of my knowledge. There are probably more subtleties to uncover. I also did some low speed tests before getting to the expressway and found the behavior to be the same - no more lowest gear in S mode. I understand the goal here was to avoid shifting into near-redline situations which could result in the limiter cutting throttle, but to me this is really an unfortunate change.

Not sure if this update happened at my last service visit or earlier. Either way, I probably didn't notice because I tend to use paddle pulls to downshift (or maybe I subconsciously started doing that more at some point because I noticed I wasn't get the best acceleration using kickdown?).

Thank you for your detailed response. Sorry it took me forever to respond. Family is in town and you know how that is.

I played around with it today and noticed that if you do a quick double pull on the paddle, (while applying kickdown) it will drop to 3rd from 7th while in sequential going 80mph. It's doesn't seem as smooth as auto kickdown or even sequential kickdown when it puts you in second lowest gear but It works. I feel you get a quarter second delay doing it this way. It's fun learning all of the intricacies of this car week after week. I swear, the minute you think you know everything the car throws you a curve ball.

So question, when you're trying to show someone this cars power and or you want to make their head slam into the seat, what do you do? (Without launching/racing) me for example will cruise at 40 or so and kickdown into 2nd. 80 kicking down to 3rd is also awesome but more risk involved, before u know it we're going 100. I feel like 40 and dropping to 2nd gear is more attainable in everyday driving. The last option is probably to get a rolling start and then punch it with shifter at 1, 2 max to avoid wheel slip and engine bogging down

[ZKing1208]

Originally Posted by CanAutM3

Actually you don't. When cruising in 7th, quickly flick the downshift paddle four times and the DCT will go straight to 3rd gear.

Yeah true but it defeats the purpose of kickdown and it takes longer. Or maybe I need quicker fingers

[CanAutM3]

Originally Posted by ZKing1208

Yeah true but it defeats the purpose of kickdown and it takes longer. Or maybe I need quicker fingers

To be honest, in 7-years if owning DCT cars, I almost never needed to use the kickdown feature. I drive the DCT more like I would drive a traditional MT, where I preselect the gear I need in anticipation of what is coming. For instance, if I want to pass another car, I would be in the right gear before I can punch it.

[CK23]

So in D if you hit the kick down + flick down one on the left paddle it will shift to the lowest gear? Therefore, if you hit just the kick down and do not touch the paddles it will go to the second lowest gear?

[mkoesel]

Originally Posted by ZKing1208

Thank you for your detailed response. Sorry it took me forever to respond. Family is in town and you know how that is.

No problem.

I played around with it today and noticed that if you do a quick double pull on the paddle, (while applying kickdown) it will drop to 3rd from 7th while in sequential going 80mph.

That’s contrary to my findings, so I’ll have to try it again. For me, it seemed to reject the second shift.

So question, when you're trying to show someone this cars power and or you want to make their head slam into the seat, what do you do?

I’d say just use the paddles to downshift to the lowest gear that will give you a little RPM left to rev while holding your speed. Then, when ready, just mash the loud pedal. Not as “sneaky” as kickdown because the high revs will give something away, but no less violent a jolt in any case.

Originally Posted by CanAutM3

I drive the DCT more like I would drive a traditional MT, where I preselect the gear I need in anticipation of what is coming. For instance, if I want to pass another car, I would be in the right gear before I can punch it.

Sure, but with an MT you can select any gear you wish in constant time. With the DCT, preselecting the gear you want takes more time (more paddle pulls) the further away it is from the gear you are currently in. That’s why the kickdown feature was handy - the right gear was always one paddle shift away. However, admittedly, I’ve never used it too frequently either. But when I’ve had the occasion, it was nice to have it available and know that it worked as you expected.

Originally Posted by CK23

So in D if you hit the kick down + flick down one on the left paddle it will shift to the lowest gear?

No, you don’t use paddles in D mode. If you do as you say - hit the kickdown in D and then downshift again - the transmission will select the lowest available gear (since that’s what the kickdown does in D mode), switch to S mode (since that’s what pulling a paddle does when you are in D mode), and reject the shift (since the lowest available gear was already selected just prior).

Therefore, if you hit just the kick down and do not touch the paddles it will go to the second lowest gear?

No.

If you are in D mode, if you just hit the kickdown it will select the lowest available gear.

If you are in S mode, if you just hit the kickdown the transmission will do nothing. It requires you to pull the downshift paddle to have any effect.

[CanAutM3]

Originally Posted by mkoesel

Sure, but with an MT you can select any gear you wish in constant time. With the DCT, preselecting the gear you want takes more time (more paddle pulls) the further away it is from the gear you are currently in. That’s why the kickdown feature was handy - the right gear was always one paddle shift away. However, admittedly, I’ve never used it too frequently either. But when I’ve had the occasion, it was nice to have it available and know that it worked as you expected.

I am ready to challenge anyone with a MT:

I am convinced I can quiclky flick the downshift paddle 4 times to get the DCT to downshift 4 gears, by skipping 3, faster than any MT driver can press the clutch, move the lever to the proper gear, blip the throttle (if not in rev match) and release the clutch.

But regardless, this goes around my point, a good driver, be it with DCT or MT, will have anticipated what gear to be in BEFORE needing it. Hence, there is no "rush" to execute the downshift.

[mkoesel]

Originally Posted by CanAutM3

I am ready to challenge anyone with a MT:

I am convinced I can quiclky flick the downshift paddle 4 times to get the DCT to downshift 4 gears, by skipping 3, faster than any MT driver can press the clutch, move the lever to the proper gear, blip the throttle (if not in rev match) and release the clutch.

I won't get involved in that debate.

The point is, the kick-down should be a reliable way to grab the lowest gear without having to worry about how many paddle clicks, etc. Sure you can just pull extra times for good measure, but not only is that inelegant, its needless movement that shouldn't be necessary. The whole point of the DCT is to allow the best performance with the least amount of user input and drama. So, I simply submit that kick-down is far better in keeping with that ethos than the alternative method of using repeated downshifts. That's why they offer it to begin with, right?

The change in behavior is, to my thinking, one compromise too many. At the absolute least, I should be able to configure the setting to give me the lowest gear or the second lowest. In fact, even better, let me set a threshold RPM that the kick-down system won't downshift above for the target gear. Or, perhaps have S2 use 5500 RPM or so, while S3 uses 7000 RPM as its target.

But regardless, this goes around my point, a good driver, be it with DCT or MT, will have anticipated what gear to be in BEFORE needing it. Hence, there is no "rush" to execute the downshift.

On a track, I agree 100%. On the street, the better driver is the one who uses the appropriate gear for the situation. That would be 7th gear for cruising at steady state, and 3rd gear for a quick passing maneuver when traffic shifts in an instant, leaving you no time to premeditate.

[radiofrequency]

I want to chime in on your post - I found a similar issue on my E92 M3 ZCP, the DCT felt not much different to the transmission on my E92 335i. I loved the E92 but that issue frustrated the heck out of me. Then I acquired a 2014 911 C4S (new) with the PDK transmission. What a world of difference, it felt like a manual when you shifted on the paddles, I thought that this is what DCT should feel like (or what I imagined it should feel like). I picked up my 2018 M4 ZCP with DCT from the Dealer and on the drive home, felt that the DCT was actually worse than that in my E92. Mike Benvo (BPM Motorsports) had programmed my E92, after that the DCT was much, much improved, and somewhat closer to Porsche's PDK. I have since purchased the Stage 1 upgrade from BPM, and started the process of downloading my vehicle info to BPM last night. I have requested the GTS DCT maps, which I understand provide a significant improvement to the DCT in the stock F82 M4. Time will tell as I am waiting for my code packet to be sent to me by BPM for download as I write this post. My hope is that in the future, BMW sources their DCT transmissions from the same vendor as Porsche, it would certainly not be a bad thing to have a transmission similar to, or identical to Porsche's PDK. Don't get me wrong, I love my M4, and there is a great deal of fantastic engineering under the skin, I am though disappointed with the DCT, and the obvious overall decontenting of the F82 vs. the E92. I will report back here after the BPM Stage 1 install with the GTS DCT Package. I've heard from others that the latter improves the DCT in terms of smoothness and overall performance.

[AtlantisF80]

on a side note:

When is the best time to shift in a DCT? When the RPMs are in the yellow? Or slightly before at 6500 RPM?

When the RPM is in the yellow and I am flooring the throttle, it doesn't feel like the car has that hard shift feel where it kicks you in the back compared to when the RPMs are are at around 6500. Is that because the torque begins to decline past 6500 and in the yellow?

Are the hardest shifts where you get that kick back action in Sport or Sport+?

[GrussGott]

Originally Posted by ZKing1208

I played around with it today and noticed that if you do a quick double pull on the paddle, (while applying kickdown) it will drop to 3rd from 7th while in sequential going 80mph. It's doesn't seem as smooth as auto kickdown or even sequential kickdown when it puts you in second lowest gear

Ok, so I spent a lot of time with this and here are my learnings comparing my remembered behavior of a 2015 vs 2018 CP:

(1.) the 2018s are greatly wussified compared to the 2015s, and this carries into the DCT big time.

(2.) Initially I got the same behavior as the OP. Then I got 4th only for both. Then I was able to get 3rd for both.

conclusion: the software gives you more leeway with "D" and it's using multiple factors to determine between 3rd and 4th. I'm not smart enough to know which but "cruising" is never perfectly flat and 3rd MIGHT be tied to slightly higher RPMs at a given speed. In any event, S & D are different, but the behavior of each is also variable and not directly tied to gear and speed (and mode).

I rarely use kickdown since I'm always in S and usually never above 4th (so this doesn't really affect me - this is my first kickdown in this car), but the 2018 CP is still new for me despite 3 years in a 2015 - it behaves significantly different ... in many way I like it less: it's a faster drive, but also with less drama and I think I'm a sucker for the dramz.

[MyNameIsNotSure]

Does anyone know if you have to hit the kickdown to truly 100% floor it? I drive in manual mode most of the time and don’t have much need for using the kickdown but I’m wondering if I just want to floor it and have 100% throttle can that be achieved by pressing the pedal down fully but not past kickdown? Or is pressing past kickdown required for true 100% throttle?

[bsmf8x]

Originally Posted by ZKing1208

I've concluded that BMW does this on purpose to prevent us from hitting rev limiter. (That's my guess at least) Because depending on your speed, you may only have a split second to change gears while in manual mode. In auto it goes to lowest gear because up shifting will happen automatically.

Same thing happened today while cruising at 40-45. If I'm in auto mode in 4th or 5th gear it will down shift to 2nd (that was fun)and when I'm in sequential it will only go to 3rd at same 40-45 speed. Kickdown in sequential seems to put car in whatever gear is above the lowest gear possible. Not the lowest gear. What are everyone's thoughts?

For novice drivers a kickdown in manual mode to a very high rpm isn't a good idea because the engine will get to redline very quickly from that. I don't blame bmw, if you want to do a pull from that speed in third gear just downshift yourself, kickdown is just for drama no actual performance gain

[bsmf8x]

Originally Posted by MyNameIsNotSure

Does anyone know if you have to hit the kickdown to truly 100% floor it? I drive in manual mode most of the time and don’t have much need for using the kickdown but I’m wondering if I just want to floor it and have 100% throttle can that be achieved by pressing the pedal down fully but not past kickdown? Or is pressing past kickdown required for true 100% throttle?

Downshifting yourself to the lowest gear then flooring would produce the same acceleration time as flooring it, pressing downshift (kickdown).

First ways safer for your engine so that's what I do. Kickdown is solely for the dramatic effect of the gear snapping down and having sudden acceleration.

[MyNameIsNotSure]

Originally Posted by bsmf8x

Downshifting yourself to the lowest gear then flooring would produce the same acceleration time as flooring it, pressing downshift (kickdown).

First ways safer for your engine so that's what I do. Kickdown is solely for the dramatic effect of the gear snapping down and having sudden acceleration.

I get all that, perhaps I didn’t word my original question clearly enough, it has nothing to do with gear changing since I do that manually and am preemptively in the right gear when I want to floor it anyway. What I’m asking is whether or not throttle is 100% open just before the “click” at the bottom of the pedal travel when the pedal is resting against that click, or whether I have to push it past that click to get true 100% throttle opening.

[TideMD]

Originally Posted by MyNameIsNotSure

I get all that, perhaps I didn’t word my original question clearly enough, it has nothing to do with gear changing since I do that manually and am preemptively in the right gear when I want to floor it anyway. What I’m asking is whether or not throttle is 100% open just before the “click” at the bottom of the pedal travel when the pedal is resting against that click, or whether I have to push it past that click to get true 100% throttle opening.

Pedal input can achieve 100% without activating kickdown.
Throttle may or may not hit 100%, despite pedal being at 100%, due to various factors - mapping, engine speed, etc.

This is best seen when reviewing logs, where you can see the accelerator (pedal) level instantly go to 100% when flooring it, while throttle opening gradually ramps up to 100% open.

[MyNameIsNotSure]

Originally Posted by TideMD

Pedal input can achieve 100% without activating kickdown.
Throttle may or may not hit 100%, despite pedal being at 100%, due to various factors - mapping, engine speed, etc.

This is best seen when reviewing logs, where you can see the accelerator (pedal) level instantly go to 100% when flooring it, while throttle opening gradually ramps up to 100% open.

Yes this is exactly what I'm asking, I'm familiar with logs from my old manual 340i. I'd do a log to verify it myself on the M3 but I don't plan on tuning it so no way to do logs.

I'm aware that pedal input does not always match throttle input. But just to confirm, you're saying that pedal input (and eventually throttle) is 100% even at the point just before the kickdown click? This would make sense because I feel it's difficult to accurately finesse the throttle at higher inputs if it has to be pushed past the click to get to 100%. There's quite a good amount of resistance in that click in my car so I don't really like pushing past it just for "feel" reasons, but I do very much like 100% throttle .

[TideMD]

Originally Posted by MyNameIsNotSure

Yes this is exactly what I'm asking, I'm familiar with logs from my old manual 340i. I'd do a log to verify it myself on the M3 but I don't plan on tuning it so no way to do logs.

I'm aware that pedal input does not always match throttle input. But just to confirm, you're saying that pedal input (and eventually throttle) is 100% even at the point just before the kickdown click? This would make sense because I feel it's difficult to accurately finesse the throttle at higher inputs if it has to be pushed past the click to get to 100%. There's quite a good amount of resistance in that click in my car so I don't really like pushing past it just for "feel" reasons, but I do very much like 100% throttle .

Correct - pedal achieves 100% upon hitting the point of resistance before kickdown button is engaged. I typically do all my runs without pushing to the point of activating the kickdown button and all logs show pedal / throttle reaching 100%.

The kickdown button itself just adds an extra little bit of travel and allows the optimal gear down shift (and Launch Control) mechanisms to activate, but is not required to achieve 100% pedal/throttle input.