Have you got both Tx and Rx lines between the emonTx and the ESP8266 connected?
Because it looks to me as if the ESP8266 is sending spurious characters to the emonTx (which is a known problem), and the emonTx is responding by going into calibration mode and replying with the calibration settings, which the ESP is then mangling and forwarding to your emonPi.
If that is indeed what’s happening, the hardware solution is to remove the output from the ESP to the emonTx, which is (confusingly) labelled Tx on the emonTx FTDI header.
Inside your emonTx, the alternative software solution is to remove the statements that send it to check the serial port for an incoming calibration command - readConfigInput() and getCalibration(). But of course, if you do that, you won’t be able to do an on-line configuration and calibration using a programmer.
