Your right and your wrong. I have the Autometer A:F gauge. I had it hooked to my left bank O2 sensor, but after that injector somehow went bad, I haven't reconnected it. Yes, the reading bounced around alot, not as bad after the longtubes, but it still went way to red when cruising and way to green at WOT, but it gave me an idea. I was kind of annoying, but it never botherd me. However, when there was a vaccume leak, or anything else that wasn't right it would show up on the gauge.