6 months ago the fuel pump wMy girlfriend's car started to run rough. I suggested a cylinder might be down. It finally got progressively worse and finally through 2 codes. I dont know where to take around were I live bc I dont trust anyone. So she took it to the Ford dealership. They checked the codes and came up with P0303 and P0316. They wanted $691 to cnage plugs, wires, fuel filter, and do a "carbon clean out" on it. I said the hell with that and put plugs and wire on it my self. (I own a 94 Trans Am that taked about 4 hours to change the plugs and wires, but only 1 hour on hers! I loved it bc it was so easy). But I did not gap the plug. I put a bottle of Sea Foam in there and it still runs rough. I found that the P0303 code is cylinder 3 misfire. I cant find too much about P0316 except that its a startup code. SO PLEASE HELP ME FIGURE OUT WHATS WRONG WITH IT. It does have a new fuel pump on there as well. Thanks in advance for any help!

 

What plugs are you using?

 

It had the original in there before I changed them. I put some autozone platnium in there.

 

Someone please help me!!!!

 

Rather than start a new thread, my friends car is having the same exact codes. The only difference is that it's the 04' with the 3.9L.

We are thinking about replacing the plugs to start, is there any brand that you guys recommend?

Also, I read on another thread, that the EGR valve can cause problems on the number 3 and 4 cylinders. Cleaning of the ports can help with that. Does that apply to the 3.9L?

Thanks for your help.

We also replaced the wires, but still the same engine codes.

 

Figured I would post some follow up.

Changes wires, plugs, fuel filter, cleaned MAF - no change.

New coil pack - runs perfect now. At least as good as a V-6 Can

 

use cooper instead i had the same problem with platinum plugs
and take the 5 minutes to gap all 6 plugs... it DOES make a difference

 

gap plugs and if cyl 3 isnt working reset the code and swap the #3 plug into #4 start it and see if the code comes up again if it does and it says #4 you havea cracked plug this happened too my friends v6 cause ome dumbass dropped the plug nd didnt say anything

 

I used the copper autolite plugs because I read another thread they were recommended over the platinums.