Broke a Bosch gen3 737 36(34)pph injector and decided to replace with new gen4 36pph injectors from FIC. Using the voltage offsets from FIC the truck will not start, using old offsets from 737 the truck runs ok (needs obvious tune but starts great). I anticipated a closer tune by changing injectors and find it hard to believe they could be so different. Similar experience out there, I figured polish up the tune- not square one?