I have a stock 7.4mpi knock sensor connected to two sensors on each side of my block. I am getting some spark retard in my blower application; however I have no knocking taking place. Dustin re-programed my ECU in the boat and he saw the retard on his laptop and we both observed no knocking while this was going on. I have upgraded all of my internals to forged parts and am running 5psi. Does any one know the differences between the two modules?

Hi Bob,
In my Volvo Penta manual they are the same. -10° if knocking.
I would imagine the electronics used would be year specific.
My Volvo Penta 310HP/7.4MPI is a 1999.