Okay that makes sense, but how does idling for a long time help the ECU learn, as opposed to just idling at stop lights? And what effect does blasting the AC have on the ECU relearning?ECU relearns the idle. Anytime battery is disconnected everything is set back to factory. Problem is, car is no longer factory new. Needs to relearn what's up, fuel pressure, vacuum, all the things based on current conditions.