Hello, first time-long time here. I have a problem that I THINK I have narrowed down to two things but I'd like to ask publicly as I'm not all that mechanically inclined.
Details:
2007 Expedition EL Limited
118k miles

About a month ago, while on a two hour drive, my truck dropped below 1/4 tank. I pulled over to fill up and it started knocking really bad and stuttering, almost as if it were out of gas. I thought "great, fuel pump's going out". I put 93 octane gas in it and got back on the highway and it cleared right up. It ran great for about 3 weeks and last Friday, when I got down to about 1/4 tank again, it started shuddering a bit. This time the CEL came on, reflecting a cylinder 6 misfire. I added fuel; didn't change anything. I added sea foam; no change. It was time to take this serious. I cleared the code and drove around a bit. It's not AWFUL, in fact, I'd drive it if I didn't need to tow my RV this weekend... that's not going to fly.

I drove it on Monday morning and it ran perfectly. No worries. Turned it off at lunch, and it started acting up again in the afternoon.

While idling in park for about 10 minutes, the CEL came back on for the same cylinder 6 code. I drove it the rest of the day with minimal problems.

Let me start by saying that I THINK it's the fuel pump. Nonetheless, here's what I've done so far:

Replaced the coil pack for cylinder 6.
Replaced the fuel injector for same
Cleaned MAF sensor

I have purchased a new spark plug and fuel filter and I'm about to embark on that journey. I'm scared to death of breaking the plug off as I BELIEVE (but not 100% sure) that it's original. I had three of my four coils replaced on the other side and I MAY have had all my plugs changed at the time. I can't recall.

Is everyone else in agreement that it's more than likely time to pay the piper and drop the tank?

thanks in advance

 

Mine had a cylinder 6 misfire under load which a spark plug replacement fixed.

 

Have you replaced all of the spark plugs?

I recently replaced mine at 103k and they were extremely carboned up. I had a cylinder 8 misfire. New plugs, and runs great now.

FWIW, I used the impact method for spark plug removal. Worked great. Used a 12volt Dewalt Cordless Impact. All out in 45min.

 

Thanks for the replies folks. I bit the proverbial bullet and removed an extremely fouled spark plug and replaced it with a Motorcraft. It's running 90% better, with no hesitations, but still idles a little rough. I'm wondering if I should put the oil fuel injector back in place since it wasn't at fault.

I'll keep the impact method in mind, but I don't honestly think that would have worked in my case. I had to give it hell to get it broken free, even after soaking some PB Blaster in there for 30 minutes. I'll look into replacing the 7 other plugs here in the next week or so. Hopefully this will get me through the weekend towing my Airstream.

 

The cylinder specific misfire codes (such as P0301, P0302, etc.) indicates that a specific cylinder is misfiring, but the code does not tell why does it happens. The possible cause might be ignition-related (worn or fouled spark plug, bad plug wire or coil-on-plug ignition coil), fuel-related (dead or dirty fuel injector), or compression-related (bent or burned valve or leaky head gasket).P0300 random misfire codes are caused by vacuum leaks (loose or cracked vacuum hoses, leaky intake manifold gaskets, or a leaky vacuum brake booster), as well as a lean fuel mixture.

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I would do a compression test on that cyl.

 

Thanks for the advice and chiming in. In the end it ended up being a fouled spark plug. I bought the $60 extractor kit from Amazon and will do the other plugs this weekend.

 

Good to hear it was just a plug issue. Good luck to you. Let us know how the spark plug change go's.

 

Yeah a little nervous there, lol. That's why I ordered the extractor first

 

CHIMES Warning lights and gauges can alert about a vehicle condition that may become serious enough to cause expensive repairs. A warning light may illuminate when a problem exists with one of the vehicle's functions. Many lights will illuminate when you start the vehicle to make sure the bulb works. If any light remains then it is misfire which occurs that could damage the catalytic converter. Drive in a moderate fashion (that avoid heavy acceleration and deceleration) and have a immediate vehicle servicing from the authorized dealer.

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