Gearbox issue, any ideas ?

[4_Series_Scania]

Guys,
I've had my 1998 E38 BMW 728i for a while now but, I've noticed since having it, its starting to take longer and longer for the gearbox to change up the gears after acceleration. For example, I'll be going down the slip road onto the A500 to work in the morning in 3rd and it will sit at 4500rpm or whatever for about 25 secs - 1 minute (sometimes less) before it changes up to 4th and then finally 5th - there's usually always a significant delay with is emphasised by high revving. I've tried blipping the throttle, coming right off the throttle but all to no avail. Also,it (the gearbox) sometimes holds onto 3rd gear till it redlines or, you flick it into manual to change up.
My Car has a VERY good service history and last week went over 103,000 miles so I find it hard to believe a ZF box will start playing up at his mileage so think it might be transmission controller - Any ideas??

(The cars covered by a "warranty" but, I'd like some ideas as to the precise cause, before my garage starts "investigasting" problems...)

My thoughts are a new ATF Filter & fluid change ,despite BMW reckoning the "Steptronic" transmission is "maintenance free" - a term I find hard to believe.

If I drive the car manually, the change up & down is smooth & instant, hence my theory about the transmission controller gizmo thingy.....  

N.B. My father has a e39 528i with the same engine & box, his car is noticably faster to change gear when in "Drive" when compared to my car, my Dads car has covered 170K+ with no attention to the box in its life...

Any advice appreciated.

[Craig.]

try changing the transmission fluid and check the oil. This seems a common problem for the same model as yours, as a quick search turned up a few of the same.

[eno]

Same as Craig said ........ also get the clutch checked ... even in an auto they can slip.

[4_Series_Scania]

Thankfully guys, it was the transmission controller, a small electrical gizmo that told the box how & when to change, its been replaced (under warranty) the car now changes gear much much faster than it did before.

I am a happy bunny !  ;)