cylinder 5 misfire

[Cvovo6]

Hello Ford lovers. I have a 2003 Ford Expedition 5.4 liter. I experienced a cylinder 5 misfire. first thing i did was change the coil pack due to it still being an older coil pack compared to the others and code. Truck still had rough idle and code never left. Next step, pulled coil pack and plug and noticed maybe a 1/4 of an inch of coolant in the plug port. I got most of it out put the copper fluid which was recommended by auto mechanic and truck drove fine for about two weeks. This past week code came back and rough idle returned.Also hearing a tapping noise I didn't hear before. Head gasket or I'm also hearing there is a coolant hose that leaks near the thermostat that can leak down into the spark plugs but don't know exactly which spark plugs this can affect. Can someone help me please. This past year I had a upper intake manifold changed but can't remember if mechanic did head gasket at the time. Is this something that is recommended while upper intake manifold is replaced??

 

[1955moose]

Head gaskets aren't changed on an intake manifold replacement. It sounds like you've got a blown gasket or cracked in cumbustion chamber of head. The gaskets fixers like you tried are hit and miss. Unfortunately you missed. Well you've got a decision on your hands, whether to repair your motor, get another motor, or another SUV.

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[TobyU]

have you taken #5 plug out and looked at it and also made sure it's nice and tight in the head?

These things blow plugs out when they loosen up.

Have to get all the moisture/coolant/dirt out of the plug well.
Either get a blow gun and a small compressor or pull plug out then start it for 4-5 seconds and it will blow it out. Then dry with rag.

 

[Mad Oshea]

You may want to do a smoke vacuum check. I had the same problem, with 8 coil pack change outs,(due to if one comes out- all come out). I put PLASMA plugs in at 5 bucks a shot. It was a vacume issue that I could not see in the real world. A skilled race car teck. did it for Me. Heck I didn't know?

 

[TobyU]

You may want to do a smoke vacuum check. I had the same problem, with 8 coil pack change outs,(due to if one comes out- all come out). I put PLASMA plugs in at 5 bucks a shot. It was a vacume issue that I could not see in the real world. A skilled race car teck. did it for Me. Heck I didn't know?

The factory coils are really good and usually go well over 150K often to 200+ so ni reason tho replace them all. They don't tend to start going out once one does.
I always keep any original or old ones when I d put all new ones in since I use cheap ebay ones anyway. The known go used ones are great for test swap outs.

Usually if you put new plugs AND boots in you are good to go for a long while.

 

[1955moose]

In theory the OEM coils will last the life of the motor, 200- 350 thousand miles. What makes them go out, is a coolant leak spraying coolant on them. If you don't have a coolant leak, or fix it right away, they last forever. The boot with the spring is what you change. That and torque down all 8 plugs around 15-18 ft lbs. These crazy thread missing heads on 97-04 Expeditions are a crap shoot at best. Too loose, they spit out, too tight they strip. Takes a Jewelers touch!

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[Cvovo6]

Thanks to all. I've had it since 2012. I'm the second owner and has really been a beast up until now. Never gave me any major issues other than the upper intake manifold. Everything else is solid. I'd hate to give up on it. I will try all recommendations to fix it starting with the cheapest. All coils are OEM coil packs with motor craft plugs. I was warned about these motors being picky at times with this issue. Keep your fingers crossed. Thanks again guys!!

 

[1955moose]

Concentrate on that one cylinder for now. Start with new sparkplug for #5, a different coil, just the one. Be sure the boot to plug is a snug clean fit. Good luck. Luckily #5 is right up front driver's side, so easy.

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[Sgt Darkness]

Also check to make sure you don’t have a bad coil wire to the plug.....

 

[Cvovo6]

To add to all of this, I found some moisture on the plug, blew out plug well and cleaned out really good. Changed plug and coil pack, can barely hear it purring. Advice to all. No aftermarket parts on the motor. Ford motors only like motorcraft parts so save yourselves the future headaches and spend a couple extra bucks. Definitely worth it