Brad Stinson

I also have a 981 S, drive in manual/sport mode 99% of the time and have never experienced the car shifting mid-corner based on throttle position. Are you talking about activated the kick down switch?

clutchplate

No I believe with the PDK it's the 4th and 5th radiators that cause such a quick reduction. That's what it says on the internet anyway.

Doug49

Interesting question. I've never noticed any "click" of a kickdown switch, so didn't have a clue there might be one. Now from some searching, I see statements that there is. It doesn't seem to me like that is what is happening. In one particular 50mph track turn (NJMP Lightning Turn 7) it happens some laps and not others. In all cases, I have the throttle hard on the floor after apex. I always thought it happened with very fast throttle application when RPMs were perceived by the computer to be low. This discussion led me to look at some data. The downshifts (3 to 2) happen about 0.5 seconds after reaching 100% throttle. RPMs are 4500-5000 and go to 6500 after the downshift so I have to shift back up within 2 seconds. But, I can find cases where there is no downshift at the same conditions (same RPM, same speed of throttle application). So, exactly why/when it happens is a mystery to me.

Kitc2246

This is the "kickdown". Actual the "button" at the bottom of the throttle is to add resistance. The kickdown is primarily based on the throttle position sensor and available RPMs. I've experienced this with my previous 09 Boxster PDK with added Sport/Sport+ and 2103 Boxster S PDK with SC. If you floor the throttle it will activate "kickdown" if there are revs available. There are two places at Summit Point that are right on the edge of two gears, one is 2-3-2 the other is 3-4-3. Normally the PDK will down shift based on speed and other factors, however if I carry a little more speed it stays in the higher gear and if I'm too aggressive on exit with the throttle it will kickdown. You can manually downshift but only if there are available RPMs. The "kickdown" will also upshift when in manual mode at redline. There is an explanation of "kickdown" in the Owner's Manual.
The Cobb PDK tune eliminates "kickdown" Also read somewhere that the GT3 and GT4 disable kickdown in Sport+ or equivalent. There are other threads on disabling kickdown. One replaces the resistance button with a solid button preventing the throttle position sensor from reaching "kickdown".