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335i DCT owners please chime in - Lag?
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04-08-2009, 08:14 AM | #1 |
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335i DCT owners please chime in - Lag?
If you own a 335i with DCT, your opinion would be very welcome.
The short story in that the current M-DCT software in the M3 is flawed. It causes a very long pause (commonly called the "lag" or the "lowspeed lag") when coming to a stop or near stop and then trying to quickly accelerate again. You can read more here: http://www.m3post.com/forums/showthread.php?t=231020 Plenty more threads here also: http://www.google.com/search?q=lag+s...www.m3post.com The lag is more prevalent when the car is in second gear but also occurs in 1st gear as well. The lag also shows up most commonly in auto (D) modes, but can occur in manual (S) modes as well. The lag is a safety issue, and has the potential to cause an accident. We M3 owners want it addressed. BMW is currently in denial mode. The reason I am (we are) looking for 335i DCT owner opinions is that that car has the same exact transmission as the M3 (similar to how the 6MT transmissions are the same in each car). However, the 335i has different (more simplified) software. So the burning question is, does the 335i with DCT exhibit this lag also? That's all. Pretty simple question ot answer if you own one. If you are unsure on how to reproduce the lag, see the thread above, or feel free to ask for more details. And thank you to anyone who can help. Oh, and since I expect some people will read this and think "there is no such thing as a 335i with DCT", please google. Also, if you want to debate 6MT vs. DCT, please seek out one of the 27 threads on M3Post already dedicated to (or hijacked for) that topic. Let's try to keep this one free of that mess. |
04-08-2009, 12:31 PM | #3 |
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I'm not familiar with the new DCT trans but could it possibly be a intentional MFR safety design so that wheel-spin can be decreased due to low mph-high rev accellerations? This could be a stupid suggestion based upon BMW's denial; I havent taken the time to search as i dont have DCT, but sorry in advance if my suggestion is retarded.
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04-08-2009, 01:05 PM | #4 |
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The lag is by no means intentional, nor could it be characterized as anything near "safety".
The fact is, the lag was introduced by a software update that was meant to fix (and did fix) other M-DCT bugs. Sound familiar? Why yes it should since this was very similar to how the notorious 335i turbo lag popped up. They fixed the waste gate rattle and a side effect was turbo lag. And just as in that situation BMW's official line is "Normal Behavior". |
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04-09-2009, 09:29 AM | #7 | |
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04-10-2009, 08:56 AM | #9 |
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they have them in europe. i dont think they have started importing them to the states yet. most forum members are in the u.s. you might have better luck posting in the regional section
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04-10-2009, 09:04 AM | #10 |
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Yes, not available in US yet (with no firm timeline as far as I know).
And thanks for the suggestion twinturboa51 - I had actually just added posts, the UK, Australia and continental Europe sections a few minutes ago. |
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04-10-2009, 01:40 PM | #13 |
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It occurs in all settings. I suppose it might be more prevalent in lower settings (like D1) due to the car shiting later. In fact, in D1, it won't even go into first gear for you I don't think (not sure since I literally never use D modes).
Yep, see my first post. It has been the source of probably a dozen discussions on M3Post, with 100s if not 1000s of posts total. |
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04-10-2009, 02:26 PM | #14 |
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I have an 07 6MT 335i, w/ DTC/DSC. And it sucks. On or off. When it's on, i can feel it kicking in any time i do anything a little more dangerous then say what your grandma would do. When it's off, DTC or DSC, my car limps on hard launches. I'm not sure if it's buggy, or if i suck. I'm assuming its buggy as i've been driving MT's exclusively since i was 16.
Can any body chime in on what exactly the best method to use (ON/ON, ON/OFF, OFF/OFF) if you slightly north of an aggressive driver? |
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04-10-2009, 02:31 PM | #15 | |
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04-12-2009, 08:56 AM | #16 |
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Hi,
I have a 2009 335i DCT. And YES: the lag is a problem in the car. Exactly as you describe I notice this at low speeds. The most common scenario is slowing down when coming to an intersection and the accelerating as the light changes. The car will not react to the throttle for a second or two. It's actually quite annoying. My old 335d with regular steptronic didn't have this problem.. it would respond immediately. P.S. PM me if you need additional information.. I'd like this to go away!
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04-13-2009, 11:03 AM | #17 |
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Ditto !
I feel the lag on my DCT too. When I change from any other gear to "D" or "R", upon releasing the brakes, it does not inch forward instantly like the pre-DCT. And of course, also the same problem that you have stated. It is really starting to bother me especially when i'm doing 3 point turns. Rgds, Mark |
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04-14-2009, 02:38 AM | #19 |
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i was all set on replacing my e90 335iAT with a 335iDCT after the e92 lci, but now i am not so sure.
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04-14-2009, 03:39 AM | #20 |
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To be sure, this is a major safety problem because the driver cannot count on the car to do as asked within normal parameters.
I don't have a DCT, but a month ago had followed an M3 with DCT out of a gas station to merge onto the main road. I could see a car approaching about 10 car lengths from down the road at a moderate pace, and if it were me (in my 6mt 335i) in front of the M3, I would have gone. So, this M3 decides to go for it... and daaayum, to my and I presume everyone's horror, it just lugs forward and just inches out despite revving it up high! If it weren't for the quick thinking and rapid maneuvering of the oncoming car, I would have had a front row view of a stupendous rear ender collision! So, yep, sometimes being on the leading edge of technology means we're the beta testers to work out the bugs.
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04-14-2009, 05:38 AM | #22 |
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Thank you for posting everyone, especially marklim and jollerbarn for your confirmation on the issue. Although BMW issued a recent update, the lag remains. In the US, we are getting as many folks as possible to complain to the NHSTA so that, eventually, BMW will have no choice to fix the issue. Hopefully that will mean it gets fixed worldwide.
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