I've driven my Tiptronic Boxster nearly 5500 miles in the past 9 weeks with no issues to speak of, except occasional irratic behavior in auto mode. The tranny always works perfectly in manual mode.
In auto:
-shifting from 2nd to 3rd, it seems to shift twice, about 3 seconds apart, almost like there's a hidden 2.5 gear.
-occasionally sticks in 4th gear and won't come out unless you switch to manual and shift it with the buttons. Then it's fine again. (only happens after tranny has downshifted from 5th, like slowing for a ramp or passing someone)
-often refuses to kick down out of 5th gear, eg. when you try to pass someone. (unless you keep squeezing the pedal down almost to the floor, in which case it will suddenly drop to 3rd, which is way more jarring than I want).
-sometimes (rarely), it will let go entirely (go to neutral?) for just a half second while shifting from 4th to 5th, then shift hard into 5th.
Either way, car seems to be weird about 4th gear.
Again, it always responds quickly and smoothly to every input when shifting with the buttons in manual mode.
Could it be the tranny ECU? Speed sensor?
Thanks in advance for any input.