I know that these problems have been discussed quite a bit on here, but my case seems to be slightly different. The truck is a 2003 F-150 Extended Cab 4X4 5.4 liter with 84,000 miles. Last Friday, the check engine light came on, yet the truck ran fine. Today, as I was driving it, it developed a small miss under acceleration, but went away. A while later driving it again, it began to become very bad, both under acceleration and while idling. It is so bad, change in the cupholders and items stored in the doors are literally rattling. It burned 1/8th of a tank going TWO miles down my road. Yes, two miles. Trying to get back to my house, the check engine light began flickering, I'm not really sure what that means either. The miss got even worse after that.

At Advance, they said the codes read #7 cylinder misfire, which leads me to think it's a bad coil, after reading on here. It also said Rich Fuel Mixture, or something to that effect. Could that be an injector problem?

Sorry for posting this, as I'm sure it's been posted before. But I noticed most of these situations didn't involve missing both at idle and at any level of acceleration. Any ideas to the real problem would be greatly appreciated.

 

Well, the bad coil would cause unburned fuel to get into the exhaust and cause a rich mixture.
Try swapping 2 coils to see if the miss moves to another cylinder. If so, replace the coil.

 

I would switch them but I don't really see a good way to get down to the #7 with all of the lines and such above it. It's supposed to be going to the shop early this week. Thanks though, I wish I knew how to work on trucks, I can usually determine a problem, but can't do anything about it.

 

you could have an injector sticking open/leaking as well

 

Yep, I wondered about the injectors. They don't seem to cause too many problems in F-150s, from what I've read, so I don't know. I'm just hoping that the repair bill won't be too high.

 

I would more believe an injector, because a misfiring plug or coil would actually show as a lean condition (I know, sounds weird, but an oxygen sensor measures oxygen, not fuel) because there is an abundance of oxygen that was unburned due to a plug misfire. If you have a slobbering injector, there would still be combustion to burn off the oxygen, but excessive fuel.

 

I took it to the mechanic today, it was the coil causing the problem. Thank you for your help.

 

Glad you got it fixed

 

Thanks, I was having a hard time dealing with losing her for a couple of days.

 

My '03 F-250 was skipping and idiling rough. I am lucky to have had the same service writer at the dealer since it was new. I ran over there and sure enough #7 coil and it needed a new PCV tube. Runs fine now. I suspect sooner or later it will happen again but replacing all 8 coils isn't in the budget (these days).

glad you got yours straightened out.