Q: Can i put an automatic engine on a manual bmw?

If you want to use an OBD-II controlled engine (2001 versus 1993), you will have to completely replace the entire electrical system on your 1993 324i (i.e., use only the 2001 model year electrical system and computers). The engine computers for the two engines you are referring to are not interchangeable. And, you cannot flash re-program your existing computer to work with the new engine because the two use vastly different computer hardware (physically different PCM’s). In addition, as noted, the wiring harnesses are completely different, and the TCM (transmission control module) will have to be completely changed as well. As if that isn’t enough, once you substitute a new PCM and TCM they will not work with the other computers on the vehicle such as the body control module but there are many other microprocessors involved as well. In the modern era, really the only way engine/transmission swaps like this can work is if you literally carry over ALL electronic controls and wiring that are associated with the donor engine to the recipient vehicle. In addition, you would have to modify the vehicle’s suspension due to the different weights of the two engine/transmission combinations. Obviously, all of these barriers make it very impractical to use anything but the original engine and so few people attempt these modifications. If, however, you are interested in an engine replacement (OEM to OEM), YourMechanic professionals in certain locales can assist with that. Please simply inquire based on your locale. If you have further questions or concerns, do not hesitate to re-contact YourMechanic.