Third time around for P0304

[kulwap]

I have a 1996 Ranger with a 4.0L. I bought it with 115,000 miles on it on July 4 2009. I now have 136,000 miles on it. About 6 months after I got it it started running really rough and it threw a P0304 code. I replaced the #4 plug and it ran fine for about 4 months. It then threw a P0304 code again and I replaced all the plugs and the wires. Today (about 2 months later) it threw a P0304 code again. What's up - any ideas? I have seen a post about leaky head gaskets, but I am not losing coolant or for that matter oil. Is the next step to replace the plug again and add a new coil pack?

I don't understand why it continues to knock out the #4 plug...

 

[fordwheelinman]

injector......

 

[kulwap]

Just noticed I posted this to the 3.0L forum... Sorry.

What more can you say about the injector?

 

[kulwap]

If it is the injector, I imagine it would be a good idea to replace all of them at once. Correct. Any suggestions as to the best place to get them?

Still not sure why changing the plugs makes a difference and allows it to run fine for awhile.

 

[mixwell]

Must have jinxed myself reading this post yesterday because my cel light came on so I ran my tester and guess what ? P0304... I'm hoping I will have better luck and mine is just a spark plug but we'll see.

 

[slvr00gt]

I have a 1996 Ranger with a 4.0L. I bought it with 115,000 miles on it on July 4 2009. I now have 136,000 miles on it. About 6 months after I got it it started running really rough and it threw a P0304 code. I replaced the #4 plug and it ran fine for about 4 months. It then threw a P0304 code again and I replaced all the plugs and the wires. Today (about 2 months later) it threw a P0304 code again. What's up - any ideas? I have seen a post about leaky head gaskets, but I am not losing coolant or for that matter oil. Is the next step to replace the plug again and add a new coil pack?

I don't understand why it continues to knock out the #4 plug...

Did you figure out what your problem was?

I have exact same issue with spark plug in cylinder #4 dies every couple of months.

I didn't look closely at the plugs I replaced 8 months ago when engine was running rough. This time around, I took a closer look at a blown spark plug. Ceramic sleeve of the spark plug post is cracked with two hairline crack running down the sleeve. The tip of the sleeve is reddish in color . Spark plug from cylinder #5 looks like new: sleeve is perfectly white. P0304 was the only code I pulled

Here is the picture of the plug:
http://picasaweb.google.com/orodionov/RangerSparkPlug?authkey=Gv1sRgCIqM-u_j1aaoRA#

 

[bilzy7]

I just bought a 1998 explorer sohc engine and within 30 miles it threw 2 codes at me. Thanks seller. I know they cleared the codes before I got it. Sob's. I only need a new 02 sensor and a fun time troubleshooting.
Hopefully tuneup and an oil change to castrol syntec 5w-30. I hate k&n filters that come on sale with oil change stuff. I just want a motorcraft filter. I try to stay with stock parts. Well see how my fun time goes with p0304 and p0153.