How do you fix a misfire in your Ford Expedition XLT?

Answer 1

Most likely its a coil, but if your check engine light is on get a dignostic and it will tell you which # misfire, then look up the fireing order and change it. First try the plug and if that doesn't fix it the deff. coil! worked for me. Not too bad or expensive of a job!

Sometimes there is an intermitent coil that will not show up with the check engine light but after awhile (could be up to a month) it will show. I know from personal experience. each plug has its own coil that sits on top and there are no spark wires on the 5.4 Triton motor

The first thing that I would recommend if you are having a misfire and the service engine soon light comes on is have a code reader determine which cylinder is misfiring. You can go to most auto parts stores and they will do this for free. If it is determined to be say the number 3 cylinder, I would switch the coil from the number 1 cylinder to the number 3 cylinder and vice versa. Recheck the code and if it comes up that the number one cylinder now is misfiring then you know you have a bad coil and replace the coil and all should be well. About $55 at a parts store. If it comes up that it is still the number 3 cylinder then it could be the plug or the fuel injector. I would put a can or 2 of fuel injector cleaner into the gas tank. Lucas fuel injector cleaner or slick 50 fuel injector cleaner seem to work well. If this doesn't solve the problem then the only logical choice would be the plug. The reason I would try the fuel injector cleaner first is that Ford has had a serious problem with the aluminum heads and the spark plugs stripping the threads. There are only 4 or 5 threads in the head and if you are not careful and do not torque the plug properly then you can easily strip the thread which may result in the plug being 'spit' out of the head causing a more serious problem. This seems to be a faily common occurrence, especially after spark plugs have been replaced and not properly torqued.