I have an 2006 Navigator with a 5.4L engine. I am having some trouble with the P0304 code. I got the P0304 code a couple of months ago. I replaced the COP and every everything was great. Last week I got the same code again. I thought that maybe the new COP was bad so I replaced it again. It ran fine okay after I replaced it, not perfect, but better. After 1 day it's throwing the code again. I have not replace the plugs yet, it just turned 100K. Any thoughts on the next place to look besides the COP??

thanks

Mburris

 

Change the plugs.

 

Check this out see if it applies to you.
http://www.stangpit.com/wp-content/i...tsb/06-2-9.pdf

 

Like JCR said, change the plugs. Make sure you gap them properly.

If the misfire persist, run a compression test to make sure you don't have a weak cylinder. If that checks out good, you may have a clogged or faulty fuel injector.

 

Thanks for the direction...I guess I was hoping to avoid the spark plug issue! I guess I know what I will be doing this weekend .

I will post my progress or solutions

Mhburris

 

Ok. With 100k on original plugs, that is sure to be your problem. And generally speaking, always look at plugs before assuming you have a bad coil.

 

I don't believe you can regap those plugs, they don't have conventional electrodes.

You are way overdue, Ford now recommends 60k plug changes on the 3v.

 

I think the Champions need to be set. I know the Autolite doesn't.

 

So I did the plug change this weekend, but still have a little stumble upon acceleration. No codes as of yet. Is there anything that I might of missed on the plug change?

Is there a trick to getting the COP on the plug good? It seemed like some of the boots were kind of loose when I put them back in. I kind of twisted them and pressed them in pretty hard. I guess the way this boot is designed it must just fit on the tip of the plug vs covering the plug like a conventional boot. I guess I was expecting a snap or something.

Any thoughts on the stumble....fuel injectors??

thanks for everyone help it has been great

Mhburris

 

I always use new boots to ensure a tight seal. And dielectric grease is essential.

Good luck!

MGD

 

Check catalytic converters

 

Need more information...

What plugs did you use? Were they gappable, and if so, did you gap them? Did you put dielectric grease inside the boots? Like MGD said, it's a good idea to change the boots to ensure a good seal.

These do not snap on the plugs like spark plug wires do. The boot covers the porcelain and the spring inside the boot presses on the spark plug.

To elaborate on what nu-supercrew said, catalytic converters can/will be damaged if you drive for an extended period with a misfire. The excess unburned fuel causes them to overheat and melt inside. The symptom for this would be a very noticeable loss in power and/or a rattling noise coming from them.

Have you ever replaced your fuel and air filters, and PCV valve? Those should be done roughly every 30-40,000 miles.

A stumble/misfire could also be caused by a clogged injector. Having them professionally cleaned is very expensive if you pay to have it done. But the next best thing is running 3M fuel system cleaner in your tank. They sell it at NAPA. It's about $15/bottle, but well worth it.

 

Used Motorcraft plugs, not gapable. I Did grease up springs and boots. Don't hear any rattling for the CC. Power is fine.

It's probably time for filters and PCV's that's stuff is easy. Ill try that...

Been running Techron prior to plug change is the 3M cleaner better?

mhburris

 

If you put dielectric grease on your springs that could be a problem. You only need to put a small amount on the boot where the porcelain is. If the stumble persist after the fuel/air/PCV, consider replacing the boots. They should come with new springs as well. You want a clean metal on metal contact from the spring to the spark plug.

If you regularly use a fuel system cleaner, it’s probably not a clogged injector. I prefer the 3M, but anything is better than nothing. The 3M cleaner takes care of the injectors, intake valves, and combustion chambers. I use their professional fuel system cleaner that runs directly through the fuel rail. But you have to have the hose, gauge, and adapter for that. That cleaner is about $35/can.

 

I pulled the boot off and put grease all over the spring and the boot. So the grease only goes on the inside of the end of the boot. not on the spring?