So we just bought a 2005 Expedition Limited 5.4L a little over a week ago from a local dealer. The vehicle has 78K on the clock and i made sure i had them change the plugs as part of the deal so i didn't have to worry about it. Truck ran fine upon delivery (wednesday night). Dropped it off Tuesday for the plug change (was running fine). Picked it up at lunch time and drove it back to work (2 miles) seemed to run fine. drove it home 5 mile seemed to run fine. On the way to work the next morning the sputtering started.

It is mainly when at idle while in gear or when in OD with the TC locked. if your sitting and idling while in gear it feels like someone bumps the vehicle with their vehicle multiple times. Then it will clean up and possibly do it over and over. Before returning to the dealership I wanted to make sure it wasn't something else.

Heres what i have done.

1. Tested for vacuum leaks with carb cleaner
2. checked to make sure all the COP connectors are secure.
3. Cleaned the MAF Sensor
4. Changed the Fuel filter (Motorcraft)
5. Changed the Air Filter
6. Added Lucas fuel treatment in case i got some bad fuel.

Sometimes you can drive it for 10 miles and not feel a thing. Other i can drive it for less than 3 and it starts. Today it has gotten a little worse. We are going to have it taken to our mechanic to have him do some testing to make sure what it is. I hate to take it an raise hell at the dealership when its something completely unrelated.

Anyone have any ideas what this might be? a COP? BTW it was not a Ford dealer who put the plugs in.

 

My guess would be that one (or more) rubber boots on the base of the COPs are cracked and is randomly allowing spark to jump to the side of the plugwell.

 

Finally threw a light last night. P0308. So i pull it in the garage and pulled the COP and plug. The COP was wet with condensation and the plug (which is brand new) has rust on it. The jack asses must have detailed the motor after they did the plug change. I pulled 1,2,5,6,7,8 and Dielectric greased them up. Ill do 3 and 4 if i ever have issues. Truck runs great now.

 

Good for you for fixing it yourself

You would have been perfectly within reason to take it back to the dealer and expect them to correct it for free. At least you KNOW it was done right this time

 

Are you sure of your cylinder numbering? Both 5 and 7 are easy to get to, so I'm curious as to why you're not doing them?

 

I'm pretty sure they are numbered like this:

Back of vehicle
7-----8
5-----6
3-----4
1-----2
Front of Vehicle

If this is the case 5 and 7 looked like they took a bit of work to get to. Im talking about cylinder numbering.... Not firing order.

Edit:

I goofed:

Its actually:

Back of vehicle
4-----8
3-----7
2-----6
1-----5
Front of Vehicle

Which means I didn't do 3 and 4 (above post was fixed).

 

That makes more sense.