I have a 2002 Ram 4.7 with 177K. Running rough, lights are on and codes displayed as misfires 300, 303, 304.

I replaced all plugs with dodge recommended Champs.

I replaced Coil 3 and 4.

This did not fix codes.

Does Multiple mean only 3 and 4 or all of them.

Took brand new plug 3 and 4 out after 100 miles. #3 is black oily, #4 is clean with good burn. Why does 300 and 304 still come up?


Also seems that my radiator fluid is constantly low, but I have no leaks visible. No radiator fluid in the oil. But my heater runs a little cool.

OK this is a lot of info, I dont care much about the heater just want to fix the misfires.

Suggestions?

 

Radiator constantly low means signs of head gasket problems if there are no leaks to be found. This could attribute to your fouling plug. Heater running a bit cool could mean your heater core is plugging up internally.

Can you swap the coils from one cylinder to another to see if the codes change or remain the same?
Did you check the gap before you installed the plugs? You should never just toss them in directly from the box regardless if they are "pre-gapped". I have seen pre-gapped plugs be completely shut before because of rough package handling. Or wrong plug in wrong box before.

 

Not a good sign, I hate to say. Hope it's a bad head gasket! But the 4.7 is notorious for having the coolant channels in the block WAY too close to the cylinders! Old coolant is VERY ACIDIC and has been shown to eat right through the block walls directly into the cylinders themselves. The symptoms are exactly what you describe, although a bad head gasket will do the same.
The head gasket issue is fixable, the other unfortunately is NOT and will mean it's replace the engine time!
I don't know if there are many posts here where people have had it eat through into the cylinder walls, but Google it, you'll see that it's an issue with 4.7s as they get up in age...

 

swapped out new coil for old no difference. i am not pulling engines PITA. did this too many times cant handle it now.

gonna try K&W sealant. If that does not work its off the cliff.

thanks

 

dont follow, what is not a good sign? a blown head gasket seems to me to be the fatal blow.

what do you mean by 'The head gasket issue is fixable, the other unfortunately is NOT'

what is 'the other'?

 

I'm thinking you have several different problems going on at the same time. A head gasket can cause a miss but being that you have bad misses on different banks and you said your oil isn't milkshake...odds are that's not the cause.

-For the coolant loss there's probably a small coolant leak somewhere that's burning up before you can visually see it...look around for dried coolant. Flush the system really good with the heat on high to clean the heater core...you should notice the heater getting a lot hotter after.

-For the misses, you have a random miss that could be anywhere and cylinders 3/4 have a bad miss. I'd verify to make 100% sure you are or aren't getting spark on cylinders 3 and 4. Pull the coils one at a time...ground them and check for spark. If you are getting spark the timing may be way off....probably a cam or crank sensor. Or it could be a fuel issue.

 

That!!!

My point was, that a blown head gasket is repairable, although very costly in labor, even if the underlying cause damaged some components such as the heads. At that point it would not be cost effective, but still repairable.
The second circumstance leaves you with no hope short of pulling the engine and replacing it. I'm not trying to be a wet blanket, but I know the issue exists on the 4.7...

 

Thanks ALL!

I will try SeVeReDiStOrTiOn Suggestions.

For the heck of it will try Injection Cleaner cant hurt, then pull 3 and 4 and check for spark.

Is the crank sensor easy to replace?

Good Forum thank you all for being there so fast.

 

You need to pressureize the cooling system and see where it is leaking.

 

Just in case anyone reads this the case is finally closed on this misfire mystery.

I took off the valve covers and rocker arms #3, #5, #7 were just sitting in the head. The lifters all seemed the same height no wear but #3 lifter was hard to remove. I replaced the lifters. No wear on rockers or lobs that i can see but did not have tools to measure.

I put it all back together, all lights went out and it runs for now. I dont know what caused this occur. Maybe hydro lock or something. Hope the misfire caused the rockers to kick out not vis versa. Anyway I never heard or saw such a thing.

It's trade in time.