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Recently, my 2013 Jeep GC is throwing a P0306 misfire code only under hard acceleration or after a downshift into a lower gear and accelerating hard back up through the gears. It is undetectable by feel or sound, but the CEL light flashes, and the code records as a pending code. The engine has 234,000 miles on it, and we've put all of the miles on it but the first 17,000. It is using some oil now, but it still runs strong. I am wondering (hoping) - is it a coil that is breaking down? Or is it the head or something else internal? The engine has had a noticeable Pentastar tick for 100,000 miles, and I've watched YouTubes about a rocker arm and lifter.

Has anyone had the P030x misfire code that turned out to be a coil or spark plug? A rocker arm? I'm willing to put coils and plugs in it (plugs changed approximately 50,000 miles ago), and I'm trying to get the courage up to even pull the valve cover, check the rocker arms, and replace as needed, but I hate to put the time and money into it if it really needs an engine. Thank you.
 

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Misfire codes are usually spark. I would replace the whole ignition system from cables to plugs, that system always does best when everything is new, and despite what some people think, the coils are not a "forever" item...they do benefit from occasional replacement.
It wouldnt hurt to do an aggressive Seafoam treatment too to clean your injectors out but thats probably just a bonus.
 
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