In the process of fine tuning my Hydra fuel map, I thought I'd install my LM-1 in the exhaust behind the Hydra WBO2. I recalibrated both in free air before checking them against each other. The LM-1 calibration is automatic, and I set the WEGO grad cal to 166 to get a 20.8 AFR in free air.
I was very surprised at how far apart the two were in operation. At steady cruise my Hydra shows 14.5 (where I set it so I don't think the sensor is creeping) but my LM-1 shows 13.7. I'm running my Hydra in open loop fueling mode right now. I tuned the map with autotune and smoothed, and was pretty happy with the results, but when I eliminated the cat, I was getting a stronger fuel smell then I expected; hence the comparison.
My WEGO zero cal is at 126 and the grad cal is at 166. Does this indicate the zero cal is off? Or maybe a bad sensor?