I have a 2002 f150 4x4 supercrew 5.4 with 108,000 just had new spark plugs installed less than 1,000 miles ago and the truck has started to misfire. I went to A7Z and they checked the codes and po304 came up misfire on cylinder #4. Any ideas as to exactly what it could be, thanks for the help in advance

 

Coil pack. They go out from time to time. Check the coil pack on cylinder 4.

 

Are they time consuming to change, something not to hard. Thanks

 

It's an easy job. Unplug the coil pack, unbolt it and install the new one. Number 4 I believe is the coil on the passenger side closest to the firewall. That one is a bit more difficult to get at but still a very simple job man. It won't take much longer than 10 minutes.

 

^^ correct #4 pass side rear . Not too hard

 

thanks for all the responses, I'll give it a try this weekend and let you know how it goes

 

Just replace them ALL. They aren't expensive and when one goes the others seem to miss it and sympathetically die.

Get http://www.ebay.com/itm/FORD-E250-E350-E450-E550-VISTEON-IGNITION-COIL-DG508-ALL-8-BRAND-NEW-/181107124114?rt=nc&_trksid=p2047675.m1851&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D163%26meid%3D7313448217986380945%26pid%3D100005%26prg%3D1088%26rk%3D1%26sd%3D170998096349%26

 

This has to be the most hilarious yet accurate description of the coil packs I have ever seen. The twin of the one that goes out first usually goes out within a few weeks for me.

 

Hey SilentButtDeadly, -What's even more Hilarious, the OP's truck doesn't use Coil Packs.

You have a scratch? Oh here? That could mean many things, - 3 came right to me, but I shouldn't say...

 

Bob, the 5fours are picky about plugs. Don't use Bosch or Autolite and you should be alright.

Desnso's (probably the best plug for this engine. It use to be the only fine wire Iridium plug made for this engine, you'll get more than just longevity,healthy longevity)
Motorcraft
NGK

I'm really a nice guy....... Honest

I'm sure someone would let me know, - if that ever changes... (?)

 

Yep, best money spent here as well.

 

Ok fellows, Just finished replacing the coil on number 4 and the old girl is running great and looking for some chevys to hurt. Thanks for all the help. I do have another problem i could use some help with. My son has a 1995 mustang with a 3.8l 128,000 miles, we changed the air filter and now it idles at 2 grand. I realize this isn't a forum for mustangs but ford guys stick together,right, any help will be great

 

Disconnect the battery for 15 or 20, then reconnect. Disconnect neg first. -Upon reconnect =Positive first.

Anything to do with air metering, you should reset like that.

 

I want to thank everyone for the tips,as it turned out, it was the throttle positioning valve. thanks for all the help.