Head scratching P0307 cylinder 7 misfire

I have a 2014 Expedition EL Limited 5.4 3-valve with roughly 154,000 miles on it. I'm new here and I haven't found a post with my issue. I have the cylinder 7 misfire code and before replacing spark plugs and coil packs, i swapped cylinder 7 spark plug to a different cylinder and misfire never moved, I did the same with the coil pack and misfire never moved. Did a Noid test on all injectors and every one passed. Ran a compression test on cylinders 5-8 and all had 150 psi compression or more. After doing all that i replaced the spark plugs, all coil packs, #7 injector (once with a injector from AutoZone and the second one a motorcraft) because i was at a point of just drawing straws, pulled valve cover off and made sure cam follower hadn't fallen off (which it hadn't and all of the followers had very little wiggle to them). None of the electrical plugs wiggle and are nice and tight on the coils and injectors. No other codes. I'm at a lose here guys so if someone could help me out it would be greatly appreciated. Vehicle is not hard to start at all, but at a idle you can tell it has a misfire and throws the check engine light.

Coil or injector wiring?

Check out FordTeckMakuloco on you tube. Apparently these motors sometimes lose the roller follower on Cyl #7. You'll want to stop driving it and pull the valve cover to be sure. Could ruin the motor if it is this.

GaryB said:

Check out FordTeckMakuloco on you tube. Apparently these motors sometimes lose the roller follower on Cyl #7. You'll want to stop driving it and pull the valve cover to be sure. Could ruin the motor if it is this.

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Video contained in this article: https://fordauthority.com/2021/11/m...8-issue-detailed-by-veteran-technician-video/

Coil and injector wiring have been checked and spark has been tested with a spark plug tester between the coil and spark plug. Also when I pulled the spark plugs a second time to check them all 8 spark plugs have the same colouration on them. As I stated in my post the valve cover has already been removed and cam followers checked in which all were in there proper places and tight with no play.

I had a stubborn misfire that eluded all of the normal cures (new plugs, moved plugs around, moved coil around, new coils, etc). Like you, the compression tests were fine, also. I eventually saw that the coil wiring connector was bad. They have a rubber ring on the inside that forms a seal around the connector on the coil, but the rubber had started to fall apart and prevent the connector from fully engaging. I replaced that one with a new pigtail, using soldered & sealed butt connectors. The misfire went away. I then decided to redo all of the other pigtails, too, and I got a new misfire code on a different cylinder. After going through the same investigation steps, I found that my solder connector had not been fully molten. A new connector and I was back up and going again. That was almost 2 years ago now and some 30,000 miles, including a trip from OK to CA while towing a trailer and an average speed of 75mph.

Do you "feel" it misfire ? Under load, or just at idle ? Might need to smoke test the intake system and check for a vacuum leak on the intake area of #7. Sounds like you've covered all the other basics.

Mechanic's Smoke Test Machine on Amazon




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I agree with Gary B. I wasted a lot of time checking plugs, coils, and injectors. The photo is of my '11 Expy. Number 7 rear intake rocker kicked out and luckily fell out of the way, so no additional damage occurred. FordTeckMakuloco at youtube is an outstanding source of information.

purevw said:

I agree with Gary B. I wasted a lot of time checking plugs, coils, and injectors. The photo is of my '11 Expy. Number 7 rear intake rocker kicked out and luckily fell out of the way, so no additional damage occurred. FordTeckMakuloco at youtube is an outstanding source of information. View attachment 77139

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Great picture, looks like that could have done a lot of damage.