That is not a swap where you can just change the motor and nothing else... As Jesse said you need the ECU and all of the appropriate sensors for the M42.
If you were going to try and keep using the M44 ECU you would need to make sure that all of the sensors are the appropriate ones for the M44. The only problem with that is that the sensors between the M44 and M42 are different. According to another member that inadvertently ended up with this same swap the M44 CPS does not fit the M42. Not to mention that that M44 ECU is mapped for the M44, not the M42. |