air flow sensor is doing my head in

2008 c50 boulavard heres the story......
brought it running really well apart from a severe crank knock ,found and fitted another engine out of a 2008 vl800 the bike will only run on both cylinders if i disconnect both air flow sensors,with them connected it only runs on one, with them disconnected its showing fi code put it into dealer mode codes are c13 and c17 air flow sensors

?is the ecu the same on a c50 as the vl800 ?there does not seem power to the air flow sensor going to the front pot only to the rear if i plug the front to the rear plug the front will work but not the rear and visa versa ,how can i trace this fault 

cheers miffa

Hi have you managed to solve the problem? I'm having a similar issue though disconnecting sensors does not return spark to the cylinder.

Cheers
Paw