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      06-02-2012, 09:37 PM   #26

Drives: 2011 535xi 8AT
Join Date: May 2012
Location: Oakville, Ontario

iTrader: (0)

Originally Posted by Three_thirty_I View Post
Mine also doesn't like somewhat quicker throttle position changes, never has. For instance, if you suddenly push the throttle down hard from a partial throttle position it usually has a nasty hesitation followed by the surge of acceleration - not a nice feeling! Even at speed I do sometimes feel a noticeable change when going between on and off throttle positions no matter how gently you go, sometimes the more direct you are the smoother, strangely enough. But I have also noticed that if you go off throttle very briefly and back on again it does behave somewhat smoother.
I'm trying, but perhaps failing, to communicate that none of my changes are particularly sudden. High performance driving schools, some time spend with fairly quick cars with no driver aids and two decades driving stick has led to me always being progressive with all of the controls. I never yank, jerk, stomp or jab at anything. I'm like Jenson Button. Even though I like to drive "spirited", my brakes and tires last relatively forever (considering the softness of the tire compounds chosen).

For instance, I may be releasing the throttle from WOT at a rate which would take a good 3 count before it reaches fully released. Somewhere around halfway, the car will "suddenly" stop accelerating as if I just side-stepped off of a bowden-cable throttle car. I don't even think I can make a drive-by-wire lurch like this if I tried.

One thing that I have made peace with is that this car does not really like fast gear changes - clutch delay valve and laggy throttle makes this quite hit and miss. Can change gears very quickly and precisely on my diesel pickup by comparison. Even things like the dual mass flywheel adds to this equation...
While this is my first drive-by-wire car, I've had cars with DMFs for a long time. I'm not a power-shifter and don't mash the stick around. I have slight pauses in my shifts through the neutral gate and pause to let the synchros do their work. I haven't removed the CDV in my E90 yet, but it was removed on my E39. My 1998 E39 still had its original clutch and DMF when it was totaled.

Just to make sure, when you say it lurches forward, you mean straight after taking your foot off the throttle it's like it briefly over-runs from the drivetrain before beginning to reduce speed? Could very well find that this is simply due to the way the dual mass flywheel behaves.
It lurches the occupants forward due to suddenly cutting power output. It's like hitting a brick wall rev limiter (except I'm nowhere near the rev limit). As a matter of fact, the first couple of times I felt it, I thought maybe I did hit the rev limiter right before shifting even though I didn't think I was anywhere near 7k (and I wasn't). I've experienced "over run" drive by wire and that's the opposite - where you've lifted off the pedal but the car keeps accelerating. I actually haven't had that with the E90 (touch wood) but have felt it in E46s and E39s with drive-by-wire. Furthermore, I'm not even off the pedal when the sudden cessation of acceleration happens - it's still halfway to the floor. When the pedal was on its way down, there was quite a bit of oomph at 4k RPM at 50% throttle, but on the way up it'll suddenly snap to "light" acceleration. On the other hand, if the whole squeeze and release only spans 1 second, then it doesn't do it a lot of the time.

Now, this usually happens in conjunction with getting ready for a shift and I haven't been able to dissect what's happening, until that experience I wrote about just recently where after the lurch it kept accelerating slowly with the pedal halfway to the floor. If I'm out on twisty rural roads in a situation where speed varies a lot, I'm running through the gears and sweeping 3k-5k RPM a lot it can happen every shift and take a lot of the fun out of it. If I'm driving to the mall, I'll probably never experience it.

I don't know what it's doing, but it makes any "fun" driving clunky, embarrassing, hard on the equipment (driveline shock) and a touch scary just because you don't know what the car's going to do. I'd almost rather be driving AT (GASP!)

IMO, get rid of all of this adaptation BS and give me a setting I can code that adapts to act like a bowden cable and stop thinking for me, thank you very much.