W203 320 7 speed box issue

[Trustmeimadoctor]

I've noticed from time to time the car seems to not want to change up and it sort of sounds like the box is straining to go but getting held back. If I let of the throttle then apply it again then it's fine and only seems to do it within a few minutes of starting driving any ideas

[donkmeister]

The car will hold lower gears and slip the torque converter when in the warm-up cycle, this gets heat into the ATF more quickly - is that the phenomenon you are experiencing?

For example, in my E500, when it's warmed up and I'm driving normally the engine rarely goes over 1500rpm before shifting up and keeps the TC quite tight, but on a cold morning it will be revving to about 3000rpm and running the TC quite loose until it gets warm.

[steve-V8s]

It will also hold a lower gear when trying to clean the DPF (If you have one on the 203)