The last map to idle control in the X is going to be something like airflow or load vs TPS. It will most likely be a 2D horizontal style table (doesnt really matter I suppose) with a minimum TPS value for a given load or airflow value.

Something like this (ignore current labels)-



Think of the purple side as airflow voltage or load, the bottom is minimum TPS duty for said voltage.

In the Subaru it uses g/s vs min tps. It works great since you basically tell the DBW to never go below this limit (i.e. 5% throttle) and use the other correcting methods to maintain target idle.

Richard or David, any ideas on this existing?