Quote:
Originally Posted by SpyderDan
Sport mode on the tranny can't have anything to do with the acceptable speed range for any gear. 29 is the limit for 1st gear, regardless. The digital gear display shows up and down arrows, telling the driver at all times when a shift either way is in range. Nothing electronic can change the gear ratios.
I think a big part of what is going on with sport mode on the AT is the interpretation of the throttle-by-wire input. Without sport mode, it seems like the throttle input is getting smoothed out for fuel economy. You can mash the pedal real fast, but the ECU smoothly increases the throttle, which feels like lag. Naturally, this slows down the throttle changes, which slows down rev-matching, which makes the shifts slower.
Sport mode, on the other hand, seems to not smooth out the throttle. The throttle reacts to your pedal input much more directly, and can be quite peaky and aggressive, at the cost of fuel economy. This translates to the quicker shift times with aggressive throttle blips.
VSC Sport mode has nothing to do with the transmission, and does not factor into any of this.
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I agree with all this or at least what has been documented (transmission range and the function of VSC Sport Mode). Transmission sport mode is obvious in its effect of holding onto gears longer and the tendency to favor lower gears for any given speed or level of throttle.
I have no reason to doubt your theory on quicker shidting in Sport mode being due to throttle response. It makes sense. I've not found any official documentation regarding the sport mode providing quicker shifts, much less why. I wish it was documented as the A/T seems to be much more complex than has ever been explained by the manufacturer. I'll guess I'll spend some time trying to discern how shift quickness differs depending on mode.
Also, I'll confuse the issue about the 29 mph "rule" (which is not much over 6K rpm in 1st). I happened to discover that although you can't downshift to 1st while cruising at thirty, you can hit the throttle at thirty and downshift to 1st at 32 or 33 mph and use the rest of the rpm range to a little above 7K before going to 2nd. It seems the tranny knows there's no reason to downshift to first above 6K when simply cruising or decelerating, but will allow you to downshift to get at the 6K to 7.2K range in 1st if you want to accelerate. Again, this behavior doesn't seem to depend on A/T Sport mode on or off.
I may not live long enough to discover all the nuances of this A/T. But it's all good.