Jamie, would an '08 Ultra Classic with Rinehart true duals and stock air cleaner need a modified map?

 

There is a huge difference between changing the AFR table and adding IED's, since the AFR/Lambda table is a "command" and feedback from the sensor is a "control"

The problem comes in when the IED's modify the O2 voltage so the ECM interprets this as the mixture is leaner than it really is. An entire block learn area can change based on this info, including the transition area outside closed loop which was already rich enough. This area now becomes excessively rich with the IED's. Another consideration is that the sensors can only measure near stoich which is 14.6:1(+/-.3) The stock sensors are simply a switch that is constantly toggling between rich/lean, if you are looking for a reference richer (or leaner) than the range the sensors are switching it is important to note they only switch from 14.3-14.9:1, there is really no way for the ECM to interpret the difference between 14.1 and a richer value, the same goes for a reference on the lean side above approx 14.9:1. Hope this helps

 

It all comes down to what is acceptable. While the ECM can adjust for some changes, it still retains the same AFR/Lambda targets as stock and and the stock timing tables are less than desirable in most applications.