Only the GEMS ECUS shave a setting for 4.0 or 4.6. The Bosch computers would have to be completely reprogrammed with new software based on a vin with the correct engine size, but as everyone said it shouldn't be needed. The MAF and o2 sensors should be able to figure out what's going on. A reset of the adaptations might help get the long term fuel trims to adjust quicker.

 

thanks for this info all...... actually have a disco 2003 4.6 v8 (motor broken).....and make a swap of motor for a 4.0 v8 2001. does anyone have any special consideration to make this change????

 

Maybe you want to keep the 4.6 crank (& I think rods and pistons?) to keep it a 4.6?
I’m really a little disappointed with the power of my 4.0. My P38 has a 4.6 and I would consider it adequate.