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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!
Why take it to a dealer to do this...very easy to swap plugs and COP's
Why take it to a dealer to do this...very easy to swap plugs and COP's
Good call, techrep. For some reason I thought he wasn't getting a CEL, but he is. Asking the mechanic to switch the plugs and COPs is no different than what he has already done.
I stress checking the wiring. Follow the wire from cylinder 5 all the way back to the PCM. You may find that it has been burned through somewhere along the way.
Anyone ever heard of something like this being solved by a PCM flash? Just wondering if somehow that could solve it.
On the other hand, if you can get your hands on a scanner that has mode 6, you may find that another cylinder is misfiring and for some reason your computer is only indicating 5 (though I've never heard of this happening). This video explains mode 6. Hope you can get this figured out. Keep us updated!
https://m.youtube.com/watch?v=PxWbZZyZlRg
Good call, techrep. For some reason I thought he wasn't getting a CEL, but he is. Asking the mechanic to switch the plugs and COPs is no different than what he has already done. I stress checking the wiring. Follow the wire from cylinder 5 all the way back to the PCM. You may find that it has been burned through somewhere along the way. Anyone ever heard of something like this being solved by a PCM flash? Just wondering if somehow that could solve it. On the other hand, if you can get your hands on a scanner that has mode 6, you may find that another cylinder is misfiring and for some reason your computer is only indicating 5 (though I've never heard of this happening). This video explains mode 6. Hope you can get this figured out. Keep us updated! https://m.youtube.com/watch?v=PxWbZZyZlRg
Excellent video, my appointment with ford is on the 2nd so I will have to get in there to check out the mode 6 today or tomorrow. Thank you for the info..
I found the problem. I had checked the mode six and noticed that all of my misfiring was occurring on the same bank, Cyl 5,6,7&8. So I took it to ford thinking it was the cam phaser. They agreed with my hypothesis and hooked it to their machine. They called me a while later to inform me that the timing system to include the CAM phaser was fine. They pulled my o2 sensor and found that the exhaust pressure was 15 and they said it shouldn't have been above 3. So off to the exhaust shop I went. My catalytic converter was completely sealed off. No air passing whatsoever. I than all who helped me through this and appreciate the advise. I guess if the Cat is bad enough it can cause some serious misfire issues.
Last edited by Big Lew; 02-10-2015 at 11:13 AM.
Reason: Added Photos
12-22-2014, 09:10 AM
