Ford Repair: 03 focus zx5, coil pack, focus zx5

Question
I have an 03 focus zx5 5 speed manual. I have a misfire on cylinder #4. I have changed plugs and wires what do i do now?

Answer
First I would like to apologize for not getting back to you sooner. I had some families issues that required attention and was away from my computer for a few days. Retrieve the trouble codes from the computer to start. This can be done for free at most parts stores. If the only code that comes back is a misfire number 4 cylinder than you have a few things to look at. Three things to consider would be a a faulty coil pack, a faulty injector, and low compression. I have to assume that you have coil packs because you did not state the engine size. The coil pack is probably your problem. Those things are not cheap, so you may consider swapping the number 4 coil pack with the number 3 coil pack to see if the problem moves. The same can be done with fuel injectors, but you have to be very careful due to their fragile nature. The last is the compression test, which never hurts. Test all four cylinders for 5 seconds. Look for any increase or decrease in 45 or more pounds of pressure.