I have a 98 f150 4.6L. The truck started to misfire. Put code reader on it and it said it was on cylinder #8. I replaced plugs and wires and found that #8 plug was bad. After replacing them problem still there. I pulled the connector off the #8 cylinder injector and problem didnt change did the same with the other cylinders and problem got worse so i know that it is #8. I also checked and made sure i have spark at the coil pack and i do. Just need to know what else to look for or any suggestions. Thanks.

If you swapped the coil pack between #8, and say, #2, and the code didn't change or the running did not get worse, then check the compression on number 8. It should be 120 psi or above, although most engines will run okay but uneconomically if the compression is 100 psi or above. Another electrical check, unplug the connector to number 8 injector, put two probles of an ac voltmeter in it,(wrap pins with electrical tape so they don't short and blow your computer) run it, see what ac voltage you read. Compare this to another cylinder, If not the same, a problem in a connector somewhere between the injector plug and the computer.

The injector itself could also be bad. If you have good compression that might be the next thing to look at. Possible swap 2 injectors to see if the missfire moves. By the way, how hard was it to pull those spark plug boots? I am having a devil of a time with them.
redwrench

OK I swapped the injector and had no change, changed coil pack and no change checked connector on injector all fine didnt get to do compresion check but was wondering if it could be the oxygen sensor. took it to the garage and put computer on it and it is saying lean on # 2 bank .