I have this issue posted in two areas for more exposure so if you see it again that's why.. I have a 2007 Ford Expedition EL with the 5.4L Triton engine. I started having power loss and misfire shaking/hesitation while under a load uphill or heavy throttle about a month ago. Codes indicate cylinder 5 misfire and a random misfire once and a while (pending). About 8 weeks prior to indications I replaced all 8 plugs with E3's and also replaced the coil packs. In the last three weeks I have moved coil packs around internally along with swapping a few from another truck trying to get the problem to move, and last night replaced all 8 spark plugs with Motorcraft thinking the truck was picky. the indications remain #5 cylinder. I have had the fuel system cleaned, and also pulled the injectors myself and cleaned them in an ultrasound cleaner. I was aiming at #5 injector so I know that one went back where it came from, however I cleaned the rest because I was there so I don't know if they got mixed up between cylinders. I don't know what else there could be. I need help.

 

1st thing to do when ever one encounters a misfire or rough running engine is a compression check, no amount of spark or fuel is going to bring a dead hole to life.

 

I found out that ford uses a nonstandard thread size so I have to order an adapter before I can do a compression or leak down check. I swapped injectors on Friday and had no change so I guess it's not fuel.

 

Should be 14mm. At least that's what it's been for the last 20 years.


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I guess it changed to 16mm I'm 2004 or something. I also read that it's different again for 2010 and up. Either way between my compression and leak kits I have 12,14,14 long, and 18 and none of them fit. It must not be to common a tool so auto part store don't have them. I did find it on summit though. I'll call tomorrow to ensure its in stock and try to get it quickly.

 

That's wild, wonder why they changed it. I would think the change year for our generation trucks would be with the new engine platforms they delivered in 2011 not 10. But in any event once you get the readings post back and we'll see what's what.


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Putting Motorcraft spark plugs in it was the correct thing, next change the cop to see if the miss changes, then the fuel injector. U will get it. Look for tracks or cracking/heat marks, Dump a couple bottles of Techron in the tank.

 

Just replaced the COP with a genuine Motorcraft DG 511. Still misfiring on #5. Also still waiting on my adapter so I can do a compression test. It's not looking good for the home team.

 

Sounds like you next need a fuel injector after a compression test. Since you only have one cyl. miss odds are head gasket is ok. Are you sure you have power to the COP and continuity back to the ECU. Same for the fuel injector. Bad connectivity can be such a pain.

 

I would also check the connector and wires going to the COP. Sometimes the connectors don't make good contact or the wires going to the connector get chaffed and would cause a misfire. Happened to me on 4 and 7