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Discussion Starter #1
Hi,

I need some advice. I have a 2004 dodge durango 5.7L Hemi with 204000kms on it. It just started misfiring on cylinder 7. It threw the code P0307.

Misfire is mild, rough idle seems fine at higher rpms. stumbles upon deceleration.

Today I removed the plugs from cylinder 7 and the spark plug gap has been reduced to almost 0 on both plugs!!!!

My immediate thought was that the piston is coming up and touching the plugs, like the connecting rod is loose, but the engine doesnt make any noise when running other than the rough idle????

Has anyone seen this before? No mechanical contact on the plugs as far as I can see.

I can post pictures of the plugs if needed.

Please advise.

Thanks. Matt
 

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Unless something was ingested and passed through the cylinder, I can't see the electrode getting hit.
Were they replaced recently? Are they the correct Champion RE14MCC4's?
 

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Discussion Starter #3
They were replaced 8 months ago. no problems till yesterday. They are the correct champion plugs as you have stated. Is it possible the piston is coming up to high? like a cracked connecting rod??
 

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Wow, that's one I've never heard of. I'd just replace both plugs and see what happens. It really sounds like they were probably not properly gapped when installed before.
 

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If dropped into the spark plug tubes during installation it can peen the electrode closed, but why show up now?
A cracked con rod or a piston hitting the electrode would be very loud.
I would re-gap as suggested and recheck them again after awhile.
 

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Did you over rev the engine?
 

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Overtorquing a plug can increase the gap, but I don't see how the gap can decrease on its own, unless there are serious deposits clogging it.
 

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This is interesting, a family member of mine has this same year and model of Durango Hemi and just last week this happened to them also. The only difference is the misfire happened about 2 days after the spark plugs were changed. Same misfire and didn't have any power. They regapped the plugs and all is well, plugs basically had no gap. Truck has 140K miles. All they could think of is they were dropped into the holes and the electrode bent, or they didn't check the gap before putting in and the box was dropped on the ground before they were put in and bent all the electrodes. They used the recommended Champions too. Very odd and I found it interesting this happened to someone else too. Engine has run fine since, if something changes, I'll let you know.
 

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Sooooo, Matt, what are you going to do?
 

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FYI - The proper torque is 13 ft-lbs (+- 2 ft-lbs) with a maximum of 15 ft-lbs. When I changed the plugs on my '06 1500 I did not have a torque wrench and just snugged them as I have any other plug. No problems to date. Truck has 170K with the plus last changed at 137K. Yeah, I know they're due again (ugh - another 3 hours under the hood......).
 

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Discussion Starter #11
So, I replaced the two plugs on cyl 7 ran the engine, drove around the block, pulled the plugs and they look perfect!! Engine runs great no noise, lots of power. I still don't understand exactly what happened. Thanks for all the help.
I will let you know if anything else shows up.

It does make me want to pull all the plugs now to look but it's -20c here....
 

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Seeing how cold it is there, if it were me, I wouldn't worry about the other 14 plugs right now.
 
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