Ailments / annoyances:

Takes about 1.5 to 2 seconds to downshift; has almost caused me to get into several accidents.

Usually downshifts by 2 gears when I'm expecting 1 and causes excessive, unneeded engine speed (rpm).

When easing off the gas pedal after accelerating quickly, holds the gear for way too long before up-shifting.

Overly aggressive automatic downshifting when breaking to a stop, causing uneven deceleration.

Often starts in D2 even though M1 is selected with the tiptronic. The reason I know this is because I can feel the initial lag before it hits first gear. PSM being off makes no difference other than the annoying light on the instrument cluster.

If this is all normal, this is the most crappy TCU programming I've ever had the displeasure of experiencing.

 

Welcome to the world of Porsche and their refusal to fix software issues after the product has been sold. I think everyone with a 955 knows exactly what you're talking about. Look into buying a pedal commander or sprint booster. Fixed the lag issues at least.

 

Doesn't sound normal.

Has it always been shifting this way or have these symptoms just appeared?

Is your idle speed normal and stable?

 

Thanks for the replies.

Villian, I have installed a sprint booster and that does add some improvement so long as the transmission doesn't shift.

bigbuzuki, it has always shifted like this. This is an earlier 04 cayenne s that was manufactured in 03 so I believe it got the worst of the TCU programming. Would a transmission fluid change help things? It has 107k on the clock and I was planning to take it in for that.