I recently installed a non-intercooled Kenne Bell supercharger on my 08 mustang GT. Since then, the check engine light indicating trouble code P0308(misfire on Cyl 8) will not stop coming on. I have changed the spark plug(Autolite HTO), and switched the coil with another cylinder. After erasing the trouble code, I have to drive the car for a few days until the light comes back on. What would be the next course of action? Change the fuel injector?

 

did youupgradethe injectors when you added the supercharger? If not then I would suggest going with at least 42 pound injectors, but if you have already changed them then you could try having them flow matched to equal out the fuel distribution. You might need to upgrade your coils to higher spark coils. How much boost are you running, because high boost can actually blow the flame off of the plug causing a misfire