Whats the process after using the battery turn off knob? (355)

Turn on the battery switch. Turn off all the accessories, AC, fan, radio, etc. Start car normally, which means without touching the throttle (you should never start the car, hot or cold with the throttle depressed, as the car needs to know the throttle position when starting). Let the car idle and warm up for 10 minutes. This allows the idle parameters to be set with the Motronic. All this has to do with is the idle settings according to the manual.

 

+1....more detail than I thought of, but this is just good practice. In the 355 and other 'modern' cars I do the same thing after disconnecting the battery, start it and let her idle for a while. Then drive around nicely at first as the ECU learns...then I do some WOT runs to learn the limits again.

 

I did the reset, and I did it incorrectly. (only let idle for two minutes) About a mile later one bank of cylinders shut down. I redid the reset correctly, and it shut down again, though briefly.
I did the reset one more time, and everything's been fine since (2-300 miles). So I think the ECU'S actually do store information for later use. Rifledriver used to say this reset process was not good to do frequently, but I forget the reason.

 

OBD2 for 96 and later 355's, I heard they do have a learning curve unlike the 95 cars

 

According to the owners manual and workshop manual, all that is "relearned" is the idle parameters....nothing more. These are old cars, not as sophisticated as more currently technology.