yes CapFirepants I confirm your thought, there is something not right, it looks like that the kline takes more time than needed to come back to HIGH
in the next days I would write a new sketch then I would suggest two other test:
- run it without L9637D connecting the logic analyzer (LA) only to the tx and rx pin of the arduino board
- run it with the L9637D but without motorbike (you would need to feed the L9637D VS pin [number 7] with 12v) and with the LA check tx, rx and k-line [pin 6]
then if everything is as expected we could move to the motorbike
I am suggesting these two test because i would like to be sure of the seput before getting to talk with the ECU. I know that this means more work, are you interested anyway in the project?