99 F250 5.4. #8 cylinder is not putting out no matter what i do. Have replaced plugs, cool packs, cleaned and rearranged the injectors and it still stays on the #8 cylinder. Haven't done a compression test yet but it will blow my finger out of the hole. So I'm thinking it has compression just not enough.

 

Could be a bad wire or bad connector to the coil or injector. Sometimes the retainer clips on the connectors fail and they don't stay plugged in. Or your wiring could have been mouse'd.

This is my little car, the #3 plug wire got eaten and you can see the nibble marks on the plug boots. The little monsters are hungry this year. There should be an obvious break in the harness somewhere, or it could be corrosion in the connector at the other end.



Sometimes they just like to eat wires. And I didn't find a place that sells these singles. This little mouse snack cost me a whole set of plug wires.