ok guys my dad has a 2004 Dodge Ram 2500 With a Hemi..just the other day it started running REALLY bad! it threw a CEL and when i had it tested it came up P0300 for Multiple Cylinder Missfire. I know this is a popular code and since it is not cylinder specific im am unsure where to start..has anyone had any success clearing this code to make their truck run normal again? could you guys give me some advice as to what the problem could be and where to start? Im thinking Plugs and Wires sicne it has 75000 miles and they r original but i am not sure. any help would be great thanks!

 

Plugs and wires would be a gradual thing and wouldn't one day start running like crap and throw a code at 75k. Before you set out on a mission to change the plugs and wires.. huge job the way the engine is tucked way back, I would look for other options. They need to be replaced, at least the plugs but it could be as simple as a clogged injector(s). Buy a couple bottles of Chevron Techron and try that, it's cost a lot but well worth it whether that is the problem or not.

 

Multiple misfire, I'd start by looking at the head gasket. Check the oil and look for signs of coolant in there...

 

ok i will check when i get home..i doubt its a blown head gasket as it just randomly started the other day and has had regular oil changes with no signs of coolant in the oil...im also going to pull a plug and see what it looks like..

so you guys dont think it could simply just be the spark plugs?

 

Could very well be and it's never a bad idea to check plugs, wires, etc., but you'd have to have had at least two plugs in two different cylinders fail to get a P0300. I'd be looking more at a single culprit that can cause multiple cylinders to misfire...

 

ok makes sense...im going to check things over when i get off work at 3..will update later. thanks!

 

I have a set of low milage stock wires and a aftermarket set of BIG blue taylor wires if you need some wires

 

ok so i just got done putting new plugs and wires in...and reset the computer. I started the truck up and it idoled fine drove it about 2 miles and it drove perfect..got to a stop sign stop and the rpms drop to almost nothing and the truck just sits there and chugs and almost stalls out..i started driving again and it was kind of sluggish like it was missing at low rpms..if i rev it up it picks right up and takes off.. so the miss is only at the lower rpms it seems. its weird. i dont know what else it could be any ideas guys? the oil looks normal no coolant mixing or anything..everything appears fine...im lost. so it was NOT the plugs or wires...but it needed them replaced anyhow so no biggie..motor sounds smooth no ticking or anything..has to be a sensor or a vaccum leak of some sort..

 

How about clean the throttle body and do a reset on it? It may be just dirty. Clean the TB and reset it with following this:

https://dodgeforum.com/forum/3rd-gen...procedure.html

Give it a shot.

 

Me: not a tech but I knew it wasn't the wires. Must have been a fun job with with a 2500 that high off the ground. Anyway, get back to my earlier thought about fuel. Low fuel pressure? Pump? Filter? There isn't any sensor that I know if that will affect the operation of only a few cylinders.

To be honest with you the best thing to do is to take it to the dealer and pay them because you're going to spend the money anyway guessing. I have been there and done that and the dealer always turns out to have been the best option in the end. (After I give up and they fix it for $150 after I spent $300 guessing) And they will be able to tell you right away if it is castostrophic