Hello, I have an 05 Expedition with the 5.4. Two weeks ago my wife was driving and it started running rough and engine light flashing. Stopped at a local car repair shop, hooked up to a scanner and said cyl 2 misfire confirmed. I told her to drive it back home and park it.

I just replaced all 8 coils about 6 months ago with Accel coils. Not many miles have been put on this since.

Few days later i swapped coil 1 & 2 to determine if it was just the coil which it was. I did this by first swapping the coils, then starting it and pulling the connectors off to listening to a change in the engine. Now cyl. 1 wasnt firing so that told me it was a bad coil. The next day I got a new coil and upon pulling the old coils out the boot was soaking wet. I pulled the #2 cyl coil out and the same thing, wet. I used a flashlight and both spark plug holes were filled with coolant. The prior day i pulled these and they were dry. No sign of coolant leak at the intake manifold or anywhere else. I blew the holes out, changed the bad coil and drove for 3 days just fine. Then on the 3rd day, started the same scenerio. Scanner said cyl 2 misfire again. It has sat a few days until i could get to it.

Today I pulled both cyl 1 & 2 again today and the holes are dry. So i am stumped as to why the holes were dry the first time, then they were filled with coolant, now dry again and another cyl 2 coil is fouled again.

Any ideas on this one??

 

Most likely is the plastic intake. Happened to my mustang with a mod motor (same design intake), even with the metal coolant crossover they can crack under where the metal crossover bolts on. Three plastic actually warps and reforms and then cracks. Id pull the intake and inspect it. Might just be as simple as a gasket too but my guess is the manifold.

 

Here's the quick and cheap fix:

 

Not if it looks like this.





That's what the attachment point for the crossover looked like on my Mustang 4.6L PI intake. The Expy attaches the same way.


Supposed to look like this.





I highly doubt stop leak will fix when they get warped like that but I guess it couldn't hurt to try. IMO, coolant in the plug wells is either a shot intake gasket or what happened to my old intake.

 

Like you said, "IF". To me it's worth a try and then at some future more convenient time, like a 72 degree and sunny day, it can be taken out of service and repaired properly.

 

I did the intake of that mustang last Feb lol. The expy intake does look a little more of a pita to do tho.

 

You'll get no argument from me on that point.

 

Yeah mine is good for now but I am not looking forward to having to change it because they all eventually do warp. Just a matter of when. Yet another reason the 03/04 navi is great (metal intake) along with the big 4r100 super duty trans.