Has anyone else experienced the steptronic having a very sluggish feel at low RPMs. My 330i has 250 miles and the initial acceleration after stopping is very sluggish. Some new owners on other boards are reporting the same thing. Any idea what is causing this?
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| Reply » Initial Acceleration Lag on Automatic 330i |
Quote: | Any idea what is causing this? | Torque converter + DBW (Drive-by-Wire) throttle.
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| Reply » Initial Acceleration Lag on Automatic 330i |
Quote: | Torque converter + DBW (Drive-by-Wire) throttle. | It would normally be expected that a fly-by-wire (or I guess drive-by-wire) system would offer improved response over an entirely mechanical system. Why is it the case here that it contributes to a slower reaction?
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| Reply » Initial Acceleration Lag on Automatic 330i |
One other thought... I've noticed that when test driving other vehicles I experience this same phenomenon. It's always been explained that this was due to some sort of heuristic in the transmission that over time adapts to your style of driving - the factory default erring in favor of fuel economy. Perhaps this is bunk, but I did notice in my last car that over time the throttle seemed more responsive... and after extended periods where my wife was the primary driver that it seemed less so.
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| Reply » Initial Acceleration Lag on Automatic 330i |
Quote: | It would normally be expected that a fly-by-wire (or I guess drive-by-wire) system would offer improved response over an entirely mechanical system. Why is it the case here that it contributes to a slower reaction? | Because although the wire can be tuned for quick response it can also be tuned in the opposite direction for smoother starts or whatever reason.
I believe this is a result primarily from the DBW settings. Either they will adapt to our style soon, or hopefully BMW will come out with a software upgrade to pick up the response time a little bit. There is just a little too much "dead" pedal travel on throttle tip-in.
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| Reply » Initial Acceleration Lag on Automatic 330i |
If you are coming to this from a manual trans, then the difference you are feeling is having to wait for the torque converter to spin up. It's that simple.
You've probably noticed that you get a good kick when you stomp the gas if the RPMs are at 3000 and a little wait if you are at 1000 - the tranny has already spun up in the first case. Go over to howstuffworks.com and go through the automatic transmission section (it really is cool to see how these things work, they've got one on SMG as well...) to see what you are up against.
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Initial Acceleration Lag on Automatic 330i