im working on doing some upgrades to a 2000 beetle and its the early 512k ECU. i would like to be able to use a later 1MB ECU with wideband OXS instead of the current ECU that is narrowband. on a quick test the later ECU does plug into the beetle's harness but if you attempt to run the car its not very happy about it. the cooling fans run all the time and its just not happy. basically what im wondering is if there is just some pin swapping/adding that can be done in the harness to make it friendly or do i have to just remove the older harness and re-wire it with a later harness. im capable of doing both jobs but im just looking for the easiest and simplest way of doing it. thanks guys.

If you remove pin 61 from the ecu connector or cut it it will stop the radiator fans from pulsing. I would pull the pin and test this that way its reversible. Ive had that fix pulsing fans on wideband swapped tt.
Adding the unitronics harness is only 2-3 pins you add to the ecu harness.
Youll want to look into where your current car is immo2 or immo3. The wideband file i was running was immo 3 but i copied the immo2 95040 from the car ecu to the donor wideband ecu and that results in a no start. You can just get a wideband ecu and immo off the 95040.
Im not sure about the 180 but on the 225's the narrowband and wideband use different mafs.