2003 Ram 2500 5.7L / P0300 & P0306 codes

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Prormk

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2003 Dodge Ram 2500
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Hey Guys,

Just joined up. What a great resource of info for our trucks.

Truck- 2003 Ram 2500 5.7L / 72,000 miles. Plugs changed at around 50,000 miles with OEM. Plugs , air filters, and oil changes are only thing EVER done to engine.

What I have going on is a slight slight rough idle, almost like the smallest skip. Codes are P0300 and P0306, General misfire / Cylinder #6 misfire.

I kept meaning to troubleshoot and dig in, however, I have two toddler boys that keep me more than busy.

Anyways, decided to dig in one day and I noticed the CEL was off. I decided to check all intake hoses, change PCV, and cleaned IAT sensor. Started it up, CEL back on. Same codes. Pulled Cylinder #6 coil and plug wire. Inspected plugs and gaps. They look good. Swapped #4 and #6 coils. Started up and drove for awhile. Checked codes, now I'm getting P0304 / cylinder #4.

Should I replace all of the coils? Is this that random of a failure to where I shouldn't worry about any near term additional coil failures?

Any other ideas of what I should check? I know the problem following the coil pretty much tells the story. What I want to do is replace coils and plug wires at this point to keep it strong.

Any input is welcomed.
 

RonJon '06

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If it were me I would replace the one bad coil pack and see how it goes, probably just a random failure.

:welcome:
 

Redtruck-VA

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Agreed, replace the coil. Sounds like you dodged the bullet by the miss following the coil. Otherwise the symptom would point at the dreaded broken valve spring.
 
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Prormk

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Thanks guys for the input.

Is P0300 and P030X typically the code that is thrown when a valve spring bails out?

I figured the system would have given me a coil specific code if the coil was bad.

Anyways, is there a write up on inspecting valve train?

Thanks
 

Redtruck-VA

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There may be, I'm not aware of one. Basically remove the valve covers and carefully inspect each spring to see if there is anything unusual. If you find physical damage on a spark plug it usually points at a broken piston. Maybe someone knows of a writeup.
 

RonJon '06

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I don't know of a write up either. Maybe try checking the spring inside the boot of the coil pack. There was a member here a while back who was getting a misfire from a rusty spring that wasn't making good contact.
 
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Prormk

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The coil boot spring is a good idea. May be hung up in there as well. Like I said, I figured I would have got a coil specific code. Well, something other than misfire.

I'll inspect / replace the coil and see what happens.

What are your favorite flavors of plug wires? Is stock plenty good? I live in Alaska and the truck stays parked outside, so cold ambients are an issue.

Any solid DIY's I could perform for a cold weather truck? I already put pan heaters on the engine oil pan and transmission pan. Have a 3way pigtail with the pan heaters and block heater into one plug. Works great.
 
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