Anyway it's working
Shame on me, I REALLY should read the data sheet first There is no crossing between tx/rx on teensy and transceiver and that was my mistake.
Thanks for help with this matter. It is always some obvious trifle.
Next thing is how to cheat the CLT in a proper way.
I'm using right now the sensor in ring-shaped aluminum housing that is mounted under the spark plug. What bothers me in this solution is slightly lower CR on the cylinder with the sensor and there is a huge reading error due to small amount of cooling air passing over the plug. What is more this error differs randomly.
Is there any solution 'by the book' to cheat CLT for air cooled engine? I was trying to lower the threshold of warmup enrichment but with no success. ECU still was able to flood the engine.