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      03-13-2013, 05:56 PM   #18
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Drives: E92 M3
Join Date: Sep 2006
Location: San Diego, CA USA

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Originally Posted by swartzentruber View Post
I've noticed that somewhat too, though I've always attributed that to DCT wanting to not downshift aggressively to save gas, not lag. If you don't brake hard, it seems like it will stay in 7 very long, so once you hit the gas, it has to downshift a lot of gears. I've noticed if I brake more aggressively, it downshifts quicker, and I don't see the issue (but that's a workaround). I'm not a DCT expert, but would 7 and 3 share the same clutch, and if it has to do that shift, it's somewhat slow? I don't think I've ever had my software updated, so I have no experience to compare to.
I think this is an interaction between the throttle and transmission control. Because the car feels like the throttle application is entirely ignored I can only conclude that it is and that it what we feel and call lag. If this can be attributed to soft braking and/or wanting to save fuel I don't know. One huge issue from my perspective is that the issues seems to be intermittent. I've certainly noticed that harder brakes causes much more aggressive downshifts as well and I agree 100% that that is a big (crappy) workaround. Odd gears do indeed share a single clutch. Although such shifts may have to be a bit slower there is not intrinsic reason a single clutch shift must be slow enough to be the cause of this duration of lag. Perhaps you go from a 30-50 ms shift to a 50-100 ms shift time. That isn't in itself long enough to be the sole cause of the lag.
E92 M3 | Space Gray on Fox Red | M-DCT | CF Roof | RAC RG63 Wheels | Brembo 380mm BBK |
| Vorsteiner Ti Exhaust | Matte Black Grilles/Side Gills/Rear Emblem/Mirrors |
| Alekshop Back up Camera | GP Thunders | BMW Aluminum Pedals | Elite Angels |
| XPEL Full Front Wrap | Hardwired V1 | Interior Xenon Light Kit |