Yes, I realize that a wideband in the downpipe is preferable to the stock narrowbands, but I am skeptical of this tailpipe sniffer, as the majority of cars dynoed today registered equally low at high RPMs (AFR remained above 12 for only one car, which happened to be the only one with its hood closed during the run, in case that's relevant). Note that I'm taking the dyno operator's word for it that
low AFR numbers are
lean and
high AFR numbers are
rich; I always thought it was the other way around (air / fuel), but it's his equipment and I have no experience with WBO2s. If I'm right and he's wrong, then this is all moot and I missed an opportunity to dial in the fuel.
My long-term fuel trims always hover right around 100 and IDCs typically peak below 90%, so I don't suspect fuel starvation. I don't know why IDCs and NBO2 voltages were so high during this session, but the dyno operator's interpretation of WBO2 readings discouraged me from leaning things out. My NBO2 sensors are a month old and I was told the WB02 has been used only a few times. I have an aftermarket single to dual exhaust with main cat intact (more complete burn?), and the WB02 was inserted into one of the four outlets as shown in the video below.
I logged my trip home from the dyno and IDCs and NBO2 readings were back to normal (<90% max and .94 max, respectively). I don't get it.