Auto questions...

[DemonDaz]

My auto gearbox is not particularly predictable!
It is on a 325i Convertible.
If I am travelling at 30 MPH (engine at suitable temp) Sometimes when kickdown is used, it will change down 2 gears and pull like a goodun.
Most of the time at 30, it will change down 1 gear and be a bit slow.

It also feels like it changes a bit too quickly (under 5000) although since fixing the thermostat yesterday, one warm it seems to rev to about 5200 (which is probably correct).

These inconsistancies occur throughout the speed range, although this is probably the easiest to pick out.

It has caused one moment of fun when coming out of a junction, good visibility could see I had time, kicked down and for a change it dropped two gears and the back decided it would swing round! I caught it before it had too much movement, but a bit of a brown trouser moment!

[MONSPORT42]

Is it a standard 4 speed or the switchable box? In any event the first thing is check the fluid. It needs to be clear and red/pink. Burnt looking brown stuff is a sign of trouble. And of course you need to have enough in there. I would also check the adjustment on the kick down cable. For 'spirited driving' I always change down manually which takes away most of the unpredictability of an auto box and gives better control and adds more engine braking.