Fitting After market ECU
Fitting After market ECU
OBD2 is attached to stock ECU so you will only maintain that functionality the whole time you have the stock ECU installed alongside the aftermarket one. I'm not aware of any aftermarket ECUs that have OBD2 functionality. You'll always need to keep the stock ECU to run the instrument cluster though, won't you?
You should be able to find a base map online for the ecu, there are hundreds out ther. You will need to set some parameters into the ecu before you can even think about firing up. An ecu may well be able to learn, but without a base setting it has no idea. You will need a base map setup for a 6cyl engine. You will also then need to specify ignition type, i.e wasted spark, batch, sequential etc. You will also need to make sure injectors are of the correct impedance. There is a lot to do which is why you pay to have it mapped.
Either way, if your fitting the ecu and then getting it mapped i wouldn't reccommend messing around or even trying to get it running, its not worth the hassle. The mappers will have a base map they could possibly send you just to check that everything is communicating properly, but i wouldnt want to run an engine on a base map for more than a few seconds at a time.
If you ask me then your best bet will always be fit the ecu yourself so your happy with the way its wired. They are very simple to install, especially with your experaince of wiring. Then get the car shipped to be mapped. Don't attempt to drive it while unmapped, unless you like rebuilding engines