The turbo failed on my September 2004 BMW 530D auto at 112,000 miles and was replaced and since the new turbo was fitted, the driving characteristic feels different. The automatic gearbox now changes up at higher engine revs and when the turbo cuts in at the higher revs, the power surge is more sudden.

Also, the gearbox tends to hold a gear over a wider rev range than before, introducing some jerkiness to the gear changes from launch and also on deceleration, particularly through the lower gears.

I had thought the turbo a mechanical device only. Might some aspect need recalibration? What other systems might be affected by changing the turbo?