Cylinder 1 is closest to the front of the engine/timing belt. For a quick down and dirty diagnosis pop the coil cover off, inspect your wiring to make sure that you did not pinch a wire when you put your plugs in last time. If that all looks could then go ahead and swap the coils from cylinder #4 with another cylinder and put it back together. While in there you can also pull that number 4 plug and see if there is a cracked porcelain or anything else that may cause your problem. Did you use a quality plug or some kind of aftermarket b.s. wonder plug? Fire it back up and see if it still misses, if it does still miss then pull the code and see which cylinder is missing. If it is still in hole number 4 then you need to consider things like a faulty plug or injector if it has moved with the coil then you need a coil to start and if it is a coil then you may have more of them in your future.

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