My automatic 740T sedan has an AW71 trans that hard shifts and sometimes takes forever to go from first to second - I have tried adjusting the kickdown to no avail.

Once in a while when I need to quickly change lanes in slowish traffic or when I need to get out of trouble, I'd stomp on the accelerator, hoping that the car would take off quickly. More often than not, gear one will hold for longer than I want and the engine then just sounds really rough as the rpms climb before second gear kicks in. One trick I have learnt so far in driving this 740 to get the car to shift up is to release the accelerator and then press down hard on it quickly.

Just the other night, I was on the freeway going at 80km/h and decided to accelerate hard to overtake. The car was probably running on third gear before I started accelerating hard. Once again the engine sounded really rough until the trans shifted up. I noticed in my rearview mirror that together with the rough sound, some smoke also came out the tailpipe at the same time. The car drives fine otherwise. It doesn't smoke in normal relaxed driving either.

Can anyone give me some ideas as to what might be the matter with the car?

Thanks!

Lucast