Join Date: Jan 2011
Location: Clarksville, Tn.
Misfire on 5.4L Expedition
A lot of people have trouble with misfired on ford v8's. I am experiencing problems right now. I have a C/E light that reads "Cylinder 7 misfire detected". A lot of people consider this an expensive problem because the coils are so expensive, and its hard to get to the back ones due to Lee Iacoca's Forward cab design putting the windshield almost on top of the throttle body of the engine and only leaving 4 inches of dreaded crowded clearance. Based on my very extensive experience, I have some helpful tips/information for you guys that suffer from these problems. For one, if it is your coil that is bad, you can get good ones on ebay for 10 a piece plus shipping. I have used them on several vehicles and they work well, Last one that I put some on has went 50,000 miles since then without a problem. But, people most of the time dont know that its actually their coil boot thats bad. What happens (thanks to Lee Iacoca) The water runs off the cowl and hits directly on cylinders 3,4,7, and 8, running past the boot into the sparkplug port and sometimes filling it up. Debris builds up in there, and corrodes, and wears the boot out with the inside heat and outside water cooling it. Sometimes the water boils a little even further weakening the boot tip. Now, this obviously hinders the connection between the coil and sparkplug itself. To fix this, you need to go to an auto parts store and pick up the amount of boots you need for about 3 bucks a piece, go ahead and pick up some motocraft spark plugs, and go back to the house and pop your hood. Now, You are going to remove the coils/boots, and leave the sparkplugs in. With an aircompressor, blow into each sparkplug port blowing out the water and debris. Wait for residue to dry, do it again to be sure. Wait for a couple more minutes and then replace your sparkplugs. When you get ready to reinstall new boots/coils, fill the coil boot about 1/4 in with antiseize, which helps prevent future corrosion of this sort, and makes it easier to remove the boot in the future. PROBLEM SOLVED! If this didnt solve your problem, then you do need a coil, have a cracked/leaking intake, or a list of other possibilities. I am goint to do this procedure right now, which is why I am sharing this information.
2001 Ford Expedition Eddie Bauer 4x4 (mine)
2003 Ford Focus SE (the wifey)