06 XLT in South Texas

[Willshooter3]

With issues... total newb to working on these beasts, hoping for some insight!

Truck is a 2006 XLT with 225,000 on the clock.
She's in pretty good shape, just dang No. 4 cylinder.
Had a buddy suggest the fuel filter might be the problem after changing coil pack like four times.

 

[Habbibie]

Welcome, are you a noob in auto mechanics In general or just on this specific truck?

Anyways it's always a good idea to change the plugs when you get a new ride just so you can eliminate any future headaches, to access the #4 plug comfortably you'll need to take off the mounting bracket for the pcm, you dont have to unplug the pcm just remove the 4 10mm bolts holding it to the bracket, wiggle it out of the way then remove the 3 10mm bolts holding the bracket in place and before you know it boom you have all the space in the world to access the that plug...

However dont too excited yet, the original design plugs break inside the head, at 225k I'm pretty sure they've been changed before but did the last guy whom changed them use antiseeze...? Just to be safe get a rental tool called lisle spark plug remover #65600 and watch youtube videos relating to that tool to understand what you might be facing.

Anyways good luck and once again welcome even though it says you joined 3 years ago!

 

[Willshooter3]

I'm a noob to working on this vehicle. We've owned it for many years. We purchased it as a lease return back in 2008. Other than standard maintenance- oil and filter- this is the first real issue with the vehicle.
I've heard horror stories about the Expeditions, the plugs and such.

 

[Plati]

why would a fuel filter cause a problem with #4 ?

 

[1955moose]

As you've probably read here a bazillion times, try swapping a coil next to that cylinder and see if the code switches. That being said, even with the cheapest of coils, 3 different ones, one of them had to work. You can get Motorcraft single coils for $30.00 each online, if you want to change that bad one later on. What Habbibie said at this point, I'd change just that 1 Sparkplug, whether you or a shop. I'm saying this just to see if code and problem goes away, then if it does, swap out the other 7. No need at this point to have broken plug problems along with your misfire. I'd also check that cylinders plug going to #4 injector, for power/pulse. We also had a member here the past few weeks, that like you kept chasing the cylinder code, tried everything, turned out to be a different cylinder. He pulled each coil plug one at a time, kept firing it back up till bingo, that cylinder he noticed no change. It was a different coil than what the computer stored as a code. Worth a shot, after you exaust all the basics. Oh an by the way your friends goofy, a fuel filter that's clogged would affect all cylinders/power, not just 1!

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[Willshooter3]

I have been through coils-cheap ones from Autozone, expensive ones from Autozone and then I bought one off ebay.
Now.
That said.
This was what I was told, didn't know if it was true.
The No. 4 is the last cylinder to fire. If the filter is dirty/clogged/no fuel gets to that cylinder and will cause a misfire.
I have no way of testing that theory.
Please don't think me foolish for believing this guy, he works for an oil field company as a mechanic, figured he knew his stuff.

 

[Jerry 2]

just wondering? are you changing the coil boot as well as the coil?

 

[1955moose]

Sounds good in theory but in close to 50 years working on every kind of car/truck/ motorcycle, I've never encountered that. Keep in mind these vehicles have a very large diameter filter. Just to clog it, you'd have to run dirty, Sandy, cruddy fuel, and on top of that not change it for close to 100,000 miles. That's why all of the regulars here, Stamp, Habbibie, Brian Gee, myself, we always state on any driveability problem fuel pressure test first. If you had a clogged filter your pressure would be low due to the restriction. Unless you've got an internal motor problem like a bad valve, or piston, etc, misfires usually come down to coil, sparkplug, or injector. In some cases it's the wiring feeding these items with positive, ground, or in the case of injectors, pulse from computer to fire that injector. Anyhoo, you'll figure it out soon, if not have a shop diagnose and fix that last leg of your repair. I do that these days, when I don't want to tackle something too intense, or I just get lazy.

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[Willshooter3]

Thank you for the info. I appreciate it.
Messed with it this weekend. Getting frustrated. Switched coils around. Still showing misfire on 4. Still running like @#$U*@#.
Thinking of ordering a whole set of coils.

 

[Plati]

2 things. 1) how long since fuel filer replaced? if its been a few years & you can get the old one off easily (not always the case), I would do that out of regular maintenance at least and MAYBE it will fix the misfire. of course like MrMoose said checking fuel pressure is closer to an actual diagnosis. 2) i had a misfire on #4 and fixed that by doing COP & plug. heres the thread for that https://www.expeditionforum.com/threads/2003-xlt-5-4-misfire-after-weeklong-rest.35179/page-2 not advised to keep running with a misfire