Hondata

I did datalog and found out that the AF reading was bit lower than the AF from wideband. Which one is more reliable?

Where was the wideband sensor placed? Before or after the cat? Has it been free air calibrated?

It was plugged into the end tip of exhaust during the tuning. From the screen the afr were drawn in a nice smooth line. But when I do the datalog, lambda table show differently (a bit).

Another question is regarding the stock O2 sensors. Os it wideband type or narrowband?

After the cat will read leaner than the stock o2 sensor. Also if the sensor is near the end of the exhaust then care must be taken to ensure it is not reading any outside air. Finally, the stock o2 sensor is wideband.

What if my cat was turbocharged and decated. So basically we not really need a wideband meter. We can rely on lambda from ecu.