Big Lew

Ok guys, I finally have an update. Although not much of a change. I checked compression and it is good. The #5 measured at 200 lbs and the others were all within 5 plus or minus.

So, to roll up what I've done. Motorcraft Spark Plugs (all 8), Motorcraft COP on #5, Cleaned Fuel system, Swapped Injectors, checked continuity on electrical connector for COP, I even hooked up an inline spark checker to watch it flash as the engine run. I can see no evidence of stray voltage, there are no cracks in the harness that I have noticed. I can honestly say the only thing I haven't done is hit it with a big ***** hammer for good measure or maybe a telephone pole.

With good compression and changing the obvious things back to OEM parts I cant help but think it is electrical somewhere. I know electricity can be funny, but im not laughing anymore.

lewissa81

Did you ever check your FPDM as suggested?
Do you get a consistent code for cylinder #5, or just once? If it only happened once, it may just be coincidental that the PCM recognized #5 as misfiring, but you still have other misfires not being detected (hopefully that makes sense). Have you checked all the vacuum hoses? There aren't many, but could cause a random misfire. If you can, see what the O2's are doing. You might have one giving false information.

Big Lew

The only code is #5. I haven't gotten a random code since October. I have checked my o2's and they appear fine. I didn't check the FDMP because it only indicates one cylinder and fuels pressure should mess with more than one. Plus, I don't know what to check other than replace and I can't just throw parts at it.

techrep

iTrader: (1)

"I started having power loss and misfire shaking/hesitation while under a load uphill or heavy throttle" .... these are all some of the signs you get when your Fuel Pump Driver module is starting to take a ****... suggest you check it ...I didn’t say replace it..remove it from the frame rail and see if the backside of the module is severely corroded and exposing the guts....

lewissa81

I completely understand not wanting to just throw parts at it.
Sometimes you can get a cylinder specific code, for a problem that's not specific to that cylinder. Misfires can be tricky. It seems like you've tested as much as you can for cyl 5, so you may need to check other components now, i.e. the FPDM. Neither I, nor Techrep is saying that is definitely the problem, but it is something you need to check.

Big Lew

So I've been under the truck for the better part of two hours and cannot find the FPDM to save my life. Online forums go back and forth to wether it was even on my vehicle. However I can find the part on fords parts site and on auto zone. If the FPDM was integrated into the fuel pump then why would there be a part available that I cannot find on the truck. Anyone know where I should look for it on an 07 expedition?

lewissa81

Somehow I missed that you have an Expy. I'm sure you saw it, but I found this thread from another site that says:
" Whenever a module had to be replaced on an Expedition it was either located on the outside of the frame rail behind the*left rear tire*or inside the frame rail to the left of the spare tire." Others state it can be hidden by a shield.
On the other hand, some models supposedly have it located in the fuel tank.

If yours is in the tank, I wouldn't focus on this being your issue right now. Being located in the tank would protect it from the corrosive elements that cause common failures. There are stories of the fuel pump shorting out, but I don't think that would cause you to get a misfire on cyl 5 consistantly.

Big Lew

Thanks for the reassurance, I really do appreciate it. I didn't mention the Expy because I was troubleshooting the engine itself. Until now the model didn't really make much difference. Tomorrow I'm gonna take another look and then start shooting wires and checking connectors again. It's has to be grounding out or something, I can't think of anything else.

Aeromech

Shoot the wires. I had a customer bring me his Passat after going to various shops and the dealer with a misfire problem. I found a broken wire in the bundle on the firewall between the computer and coil pack. Fixed it with a butt splice. I was his hero.

Walkerrun

I had the EXACT same symptoms. I know you have already tried spark plugs and COPs so I think it is wiring. It definitely sounds electrical, whatever it is. I'm not sure if the Expeditions had this problem, but some of the f150s had a problem with the AC line burning through wires toward the back passengers side of the engine. I would definitely check that spot.
On the other hand, I went through these same steps but didn't get a CEL after replacing spark plugs and COPs. I broke down and took it to the Ford store for diagnostics (about $100). When the mechanic found the misfire on cylinder 3, he moved the spark plug and COP to cylinder 2. Ran the diagnostics again and the misfire was now on cylinder 2, showing that the culprit was that spark plug or COP. Turns out, I got a faulty MotorCraft plug out of the box. Just saying, it can happen! If you can't figure it out, I'd recommend taking it to Ford for diagnostics. Ask the mechanic to move the spark plug and COP to a different cylinder and run the diagnostics again. Hope you find the problem!