Hey everyone, I've got a 2005 Expedition with about 130k on it. A couple of days ago my wife was driving it home and noticed a miss and the engine light came on. Codes came back as cylinder 1 misfire (P0301), misfire at startup (P0316), and O2 sensor sensing rich (P2196).

I bought the rig with just over 110k on it and haven't replaced the plugs or coil packs on it.

So far, I've pulled the spark plug in cylinder 1. It smelled like gas and was wet and black. I figured it was a coil pack that wasn't firing so I got the HEI spark tester, hooked it up and tested the coil pack. It sparked like crazy. I replaced the plug, put the coil pack back in, drove it about two miles and it had the same symptoms as before. I pulled the new plug and it was solid black and smelled of gas again. Thinking I was getting a weak spark from the coil pack, I switched the cylinder 1 pack with the cylinder 5 pack (both at the front of the engine) to see if it would turn the cylinder 5 plug black. It didn't.

I don't know what else to check. Any ideas?

Thanks!

 

Sounds like it has fuel and spark, so there's two components left needed for combustion, air and compression. Since it sucks in fuel, and the rest of the cylinders are fine I'd assume it has air and that leaves us with compression. Do a compression test, and if you get low compression on cyl 1, do a leakdown test to find out where the compression leak is.

 

Chances are, it's just the boot on the coil. Try trading it again with another cylinder, or just spend the $5 on the new boot. I changed my first "bad" cop on a 5.4 this weekend. Failes when the truck gets to operating temp.

All It would take is installing It just right, to seal a spark leak.

 

The air filter was pretty dirty, but I agree that it is likely something else. I'm going to clean it up anyway. I thought of doing a compression test but I don't have a gauge. Sounds like I'll need to pick one up.

I checked the boots and didn't notice any cracks or anything. Could it be carbon build up inside maybe?

I won't be able to mess with it for a few days because we will be in the hospital having a baby tomorrow. Was hoping to get this wrapped up beforehand but I think that ship has sailed.

Has anyone had to flash their computer after having misfire issues?

 

The air filter would effect more than one cylinder. When you say clean It up, are we by chance talking a k&n or other oiled filter?

If so, I recommend cleaning the maf. Still a good idea , either way.

As far as the boot goes, all it would take is a pin hole that you sealed by twisting , when you moved it to another cylinder.

 

Well, since swapping it with another COP didn't move the misfire, chances are the coil is fine and is producing a spark, but sure, could try to swap it again. Just for kicks, try to swap the plug or even put a new plug into it just to rule out anything on the plug itself. But if swapping both plug and coil from another cylinder doesn't give any results and the misfire is still on cyl 1, chances are that the problem is not with ignition. You could try to swap the injector to another cylinder, but since the plug was wet it seems it's getting fuel. It's not too difficult to move a injector, so it's something you could try.

While it doesn't hurt, I don't think the misfire will be cured by a simple MAF or air filter cleaning. If these cause misfires, they're random and not just on one cylinder. But, there's one important point on the misfire code, just because it flags cyl 1 on misfire, doesn't mean the other cylinders never has misfires. It just means they didn't do it as much as cyl 1. The way to check this would be with a scanner and check the misfire stats for all the cylinders, this may help to verify that it is indeed an isolated problem with cyl 1. If that's verified, then I'd suggest a compression test to check if it has any compression leaks.


Edit: If you have a good enough scanner, a power balance test would also be helpful to do. But your generic china OBD scanner won't be able to do that.

 

Check the wires to the coil. Maybe there is a break or poor connection that only shows up when everything is properly installed.

 

If you changed the plug and the coil....and you saw the wet gas on the new plug...it is definately time to do a compression test on that cylinder...every thing else (maf map air filter) is just grasping at straws....Congratulations....is it a boy or a girl?

 

I also found that most compresson testers dont come with the 16 mm fitting that screws into the 5.4.(spark plug hole)..It was a seperate purchase from napa for 12 bucks

 

How come no one has suggested the injector is leaking and creating an overly rich/flooding condition in that one cylinder?

 

I did suggest swapping the injector over to another cylinder...

 

Well, it's a boy! Everyone is well and home now so I guess it's back to work.

Thanks for all of the replies. I'll clean up the filter (pretty sure it's K&N like my other Fords) and try swapping the injector. If that doesn't do it I'll get a compression gauge, and if that doesn't do I guess it's in to the shop. I don't have a scanner. Thanks for your help. I'll let you know what I find out.

 

Congratulations!

 

Congratulations from me too.

 

Well, I pulled off the fuel injector and gave it a non-standard highly unprofessional leak test (I filled it with carb cleaner and blew on one end until carb cleaner came out the other end). I'm guessing that my "blow-pressure" shouldn't cause it to leak? Highly scientific, I know.

Hopefully I'm in luck and it's just the injector. Also, carb cleaner doesn't taste good.