Hi Folks,
Like many other, I have the cylinder 5 misfire problem. I have run out of ideas. Here is what I have done:
1. Replaced Cylinder 5 Spark plugs
2. Replaced Cylinder 5 Coil Pack
3. Swapped Cylinder 1 and 5 Coil packs
4. Swapped Cylinder 1 and 5 Fuel Injectors
5. Replaced Cylinder 5 spark plugs with premium type
6. Scoped both cylinder 5 spark plug holes for deformities or leaked oil from valve cover gasket (none found)
7. Did a compression check on Cylinder 5. It was around 200, which in my opinion is great.

This is on a 2012 Dodge Ram Laramie Longhorn with the 5.7 Hemi.

Anyone got any other ideas on what I can try next ?

Thank You,

Eric

 

Put a noid light on the injector connector, and verify it is flashing reliably. Do the same for the coil connector...... see which one is erratic.

 

Hi,
A noid light ? What is that ?

Also, he error code isn't a hard error. It takes several minutes of driving to appear.

Thanks,
Eric

 

Sounds like a mechanical issue rather the the electrical stuff you've pretty much eliminated. Flat lobes or broken lifters will throw codes and you can still have good compression.

 

Diagnostic tool. Parts stores will know what you are asking for.

 

Cam shaft and lifters is what I am afraid of. If I pull the valve cover, can I pull the push rods and lifters
and inspect the camshaft ?

Also, I'm pretty sure that there is a timing sensor that is the basis for the fault code, in that the computer
can sense the minor timing differences and determine what cylinder isn't firing. Where is that sensor located ?

Thank You,

Eric

 

I think the dealer can diagnose with the valve covers off. Unfortunately, to get to the lifters, the heads need to come off.

 

Wow, you would think the lifters would lift out with a magnet....

One thing I haven't tested is for intake leaks. I'm going to try that and repost.

Thanks,
Eric

 

Silly question but is the truck running bad? The reason I ask is because I had a similar issue P0303 code that would come and go for about a year. The truck ran fine but the stupid light kept coming on for a couple days then it would go off for a couple days. I did all the things you did plus had my cam, lifters, and sensor changed and I still got the light. I know this is going to sound stupid but I had a bad puddle light on my drivers side mirror (it would come on sometimes, others not) and I finally changed that light and I haven't got another check engine light (P0303 code) since. You might look around and see if you have any bad lights on your truck, I am certain that mine was an electrical problem. If your truck is running bad ignore everything I just said!

 

It intermittently idles bad and sometimes when I punch it, I hear a backfire. So its intermittently running bad.
Because of the time change, I don't have enough daylight when I get out of work to troubleshoot.

This weekend I'm going to check for intake leaks and then if that doesn't pan out, I'm going to pull the
valve cover and see what is going on.

Thanks,

Eric