Hello everyone. Let me start on the list my 04 ranger 3.0 v6 gave me cylinder 6 misfire code. And threw misfire detected on engine startup. I replaced plugs. Wires. And the fuel injector. Still threw the code. Up until my overflow started to bubble on my(not boil). I immediately changed the radiator cap, thermostat. And a few days later I changed the water pump. Now it's only bubbling after I loosen the cap after sitting all night. But when I drive the overflow fills up but not overflows. So after a mile it goes up about 2 inches in the overflow. Has not flowed over yet since the water pump Change. I'm went to autozone(stupid Fks) could not tell me anything. The Haynes book told me minimum. Google search told me to look at the dipstick and see if it is milky after it warms up no water/coolant in the oil. No oil in radiator. No coolant smell in exhaust. This issue has been irritating me for a week now, please help me. The misfire code still had not come back. I checked forums and similar issues but not exactly the issue so I know for now that it's not the head gasket... Any ideas?

 

If you continue to get cylinder misfire codes (P0300-306), as well as the "misfire on engine start up" code (P0316), then you have to at least consider the possibility that the head is shot due to valve seat recession. You need to do a compression test and a leakdown test.

See: Ford TSB 05-26-3