A number of people have various problems with the AEMWB display routine. There are a number of reasons for this, but most seem to revolve about the AEM's weak analog driver circuitry. It's simply unable to properly drive a number of ECU inputs.

One fix is to buffer the ECU input with one of these. In doing so, the AEM is not required to drive the ECU input directly.

People still seem to get varying results, though. So another fix is to simply not use the built-in AEM WB display routines and instead define your own using the LinWideband display item. To use that, you change the pin assignment to be Linear wideband and then manually adjust the mapping.

One user found the following settings to work well on his own AEM WB install:

Min Voltage: 0.0
Min lambda: 0.65 (gasoline A/F ratio of 9.55:1)
Max Voltage: 4.99
Max lambda: 1.32 (gasoline A/F ratio of 19.43:1)

AEM has now come out with yet another mapping with their 30-5130 gauge (at least this gauge seems to have a separate analog ground, the brown wire, that should be connected to ECU sensor ground to improve the ability of the WB to deliver accurate voltage readings to the ECU):

Min Voltage: 0.62
Min lambda: 0.598 (gasoline A/F ratio of 8.79:1)
Max Voltage: 4.37
Max lambda: 1.203 (gasoline A/F ratio of 17.69:1)