Trying to understand Banks

I have been playing with a real time data analysis program that plugs into the OBDII port. The results are a bit confusing. On the 360, the information provided is oddly incomplete:

1. Short Term Fuel Trim is provided only for Bank 1 and Bank 3 [Bank 3???]. BTW, Long Term Fuel Trim is similar: Banks 1 and 3, differing by 8-9%
2. O2 Sensor voltage is provided only for Bank 1 sensor 1. When the program (ScanXL-Pro) tries to read the other three, they are not among the PIDs that the car ECU reports as 'supported'.

At first I thought the 'bank 3' thing was just a mislabeling, so I started worrying when the bank 3 STFT reading was consistently 9% higher than bank 1. After much experimentation, including disconnecting all 4 O2 sensors to force the car into default mode of operation, the 9% difference was still there.

I had heard that the 360 only presents data via OBDII for Bank 1 and that you have to use the SD2 plugged into the other diagnostic port under the dash to read the other bank. So, on the theory that I was just misunderstanding what was meant by Bank 3, I recorded the same data on my 2001 BMW E39 M5. The BMW presents data for 4 banks (1-4), with banks 3 and 4 being 10% higher than banks 1 and 2. So this leads me to believe that the Ferrari was indeed correct in presenting the 9% difference and that it was indeed presenting only one side of the engine (banks 1 and 3).

So, does anyone know what it means on a v8 engine to have OBDII data presented for 4 banks? If the fuel trim perhaps managed for each pair of cylinders rather than for each entire side?

I am attaching screen shots for both the 360 and the M5. I have traded notes with tech support for ScanXL, who helped me get past some initial misconfigurations, but everything seems good from his side now and the view from the M5 seems to indicate that the program is working correctly.

The 360 screen shot is here. I'll post again with the M5 screenshot.
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Here's the screenshot of the data read from the M5. The car presents data for 4 banks (still confusing to me) in addition to presenting data for all 4 O2 sensors.
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A related question, that I have seen across 3 different OBDII code readers:

I have seen cases where the CEL comes on but the readers claim there are no error codes (no DTCs). For other problems over the years, there have indeed been error codes, so this is not related to the OBDII service campaign on the 360s (which my car already has).

Has anyone else seen this condition (where there is a CEL but no error code)? I have been told that this is common when the error is detected by bank 2, but I have never heard any other mention of it.



Lou