I recently purchased a 2001 expedition RWD with the 4.6l COP configuration. It runs great above 2000 rpm but has a miss at idle and on the highway between this range. I also had the code P1406 and found that one of the hoses to the egr had come off. It started running better when I put this back on but still a slight miss. The other thing to note is that the engine was washed just prior to me picking the vehical up. I sure wish that they had not done this from what I am reading. I guess at this point it can be the plug, the coil or an injector on this cylindar. I am terrified to pull the plug from all of the horror stories I read about the aluminum head. Should I worry, or is this rare that the plug gets stuck? I pulled the coil and looked down in the hole and it looks nice and clean a dry. It also appears to me that the orginal coils and plugs are still there from the factory. Milage on the truck 81k. Please let me know what you think.

 

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I appreciate you getting this to the right spot.

 

Once they get washed, if it fries a COP, it is usually done for. 301 is a cylinder 1 misfire. The easiest way to see if it is a bad COP is to move the C1 COP to another cylinder and see if the misfire code follows it. You can replace the COP boots without replacing the whole assembly, I'd suggest replacing them all either now or for sure when you replace the plugs, which it is due for if they haven't been done. With this misfire I would expect the actual COP to be bad though not a boot problem.

 

I sure do appreciate your input. After posting this I went ahead and replaced the COP on that cylindar. It now runs great. After a few starts and about 40 miles the check engine light went out. I just hope that the plug is not fouled. I did not change the plug even though I wanted to. I am afraid of the problems that I read about blown plugs.

 

From my experience with the COP and plug changes, I have learned: You are about maxxed out on mileage for your plugs if they are the original ones. You would benefit from installing new ones. I've had to do several plug and coil changes on our 5.4 Expedition and haven't experienced any of the horors that I've read about so far. When I do replace the plugs, it is usually a result of having to replace a bad coil. I generally put the newest coils on the rear plugs closest to the firewall. That way, if I have another one go bad before the next plug change, hopefully it will be one of the older ones close to the front of the engine that is easier to get to. We've got 300k on this engine and still have two of the original Motorcraft coils in it, and they are sitting on top of cylinder one and two right now.

 

That is good to hear. That is also a great idea on moving the old coils to the front. I will definity do this as they fail. 300k this engine design can't be as bad as some make it out to be. I had a 3.8l taurus that I got 243k out of before I sold it a year ago. I still see it on the road on occasion. The way I see it is there are going to be problems with all engines. I sill will be holding my breath as I change those plugs for the first time. Do you always get a fault code on the cylindar when the COPs go?

 

Yep, every time. I also get the stumbling when I accelerate (put a load on the engine). The code doesn't always "set" when the problem first starts. If the CHECK ENGINE light just flashes, I don't necessarilly get a code thrown, but when the idiot light stays on I can pull a code out of it. I connect my code checker to the vehicle and drive it until I get the problem to repeat itself. When it happens, the diagnostic checker always catches it whether the check engine light does or not.

Just take it easy with the plug removal. Try to stay straight above the plug and keep the torque steady and smooth. That can be hard with the ones near the firewall (I make use of extentions and universal joints on those). Just try to keep the side torque to a minimum. I've never used anti-seize on the plug threads so far. Knock on wood: I haven't had a plug stick yet. I just don't overtighten the plugs.