To all that may be able to point me in the right direction. I have a 2003 5.4L Expedition. It has been a good vehicle up to about 6 months ago.

It started running rough so I changed out the plugs. (This was around 100,000 Miles). It ran fine for about two months, and started to run rough again. It finally through a CEL and the code came up "Misfire on Cylinder #8. I changed the COP and it ran good for about 25 miles. The CEL came on again and this time it was "Misfire on Cylinder #6". I changed the COP and it ran fine for about another 25 miles.

Needless to say, it started to run rough again, so I ordered 8 coils off of e-bay and changed them all out yesterday. I cleared the CEL by disconnecting the battery cable and it ran fine for about 1 mile and then started acting up again. I am at a loss on what to do next. It has only been 6,000 miles from the time I changed the plugs (Motorcraft) to the time I replaced all of the coils. Should I try replacing all of the plugs, or is there something else I should be checking?

I have not checked for vaccum leaks yet. Plan on checking that out today, but basically ruled that out since the truck ran fine for a while after changing the coils.

Definately do not want to take to stealership. The 2 hours I spent yesterday changing all the coils, would have cost me an arm & a leg at the stealership.

Any advice would be helpful. Thanks in advance.

 

Any codes after replacing all 8 of the COPs?

 

Alloro,
Unfortunately I do not own a code reader. The Auto parts store won't hook up to my vehicle unless I have a CEL, which I do not have at the present time. Looks like I need to invest in a code reader or the software for my laptop. Thanks for the assist.

 

did you drive it yet or after disconnecting the battery and clearing the codes and KAM when you started it up it runs a little rough, take it for a drive and go full throttle a few times so it will relearn the baro that should help,

 

OK. I started the Expy to move it into the garage to look it over and to my surprise, it ran great. However, after about 7-8 minutes of idling, it started running rough again. I took your advice ''fordtech08, and ran it full throttle for a bit. It seems to run somewhat smooth, but still with some hesitation. Truck runs really rough when I am in park and I throttle up.

Still not sure what is going on with this truck.

Ideas?????

 

did you run it at full throttle while driving or while parked? since you no longer have a check engine light I'd also suggest you look at your maf sensor to see if it's dirty

 

I would check your MAF to see if it is dirty or damaged, do not clean it with carb cleaner you will destroy it. If you want to clean it use MAF cleaner, at any parts store. To me your problem sounds like it starts acting up after the truck is warmed up and when it changes from open to closed loop. I would invest in a scanner to see what the code is and so you can check it for further reference. Your problem sort of sounds like a fuel or sensor problem but since you said it happened after you warmed it up a little bit then I would guess its something to do when the computer switches from open to close loop for the fuel system.

 

dirtmonkey11,
Thanks for the Tip. I will check the MAF, and look for a good scanner to pull the codes for reference. Thanks.