I had a cylinder #5 misfire for the past couple of days. I changed the plugs, air filter, fuel filter. I also tested the coil packs and injectors. They were all within spec, but I still had the misfire. Today I bit the bullet and took the truck into the dealer. They found that the #5 cylinder coil pack wasn't contacting the spark plug as it should and some of the spark was going around the plug, not through it. There was a slight carbon line on the ceramic portion of the new spark plug. Just thought I would throw that out there as it seems like there a lot of misfire problems out there. I thought for sure that I would be buying a new injector..

 

So you had a loose #5 coil pack ? How did you test the coil packs and injectors ?

 

Yeah, I guess it was loose or something. I tested the coilpacks and the injectors with a multimeter, but the bad coilpack still tested within spec.