So jeep seemed to be running ok, I put on new valve cover gaskets and thought I might as well change the plugs. Jeep has 153K on it but I've only had it for about 3k miles. Judging by how hard it was to break these plugs loose I'm thinking they were the originals. I don't see how tis thing was running (2010 Unlimited). These are exactly as they were removed, looking just like this.

 

how the heck.........?

 

I have no idea. I'm going to put them on a plug wire and see if I can see how they were even sparking. I can't believe this thing was even running much less starting right up and running smooth.

 

Bet your fuel mileage went up with the new ones. Wonder if a slightly colder plug heat range would help there as well.

 

I believe that the manual calls for changing plugs at 100K. Trust you put MOPAR/Champions back in.. those appear to be Champions and went 153K ..

 

WOW that is impressive. I would have never believed it would have been running fine with spark plugs that looked that bad.

Bob R

 

One of the best pics ever on this forum. Amazing. lol

I do plugs once a year to make sure they come out easy and don't get seized. I also notice a huge performance increase with new plugs.

I just recently did plugs and wires and went with the Denso brand for $30 wire set over the mopar this time with 206k on the JK. No difference in performance. So at $4 a plug and $30 wire set I find value in doing it often. Coil pack has only been replaced with mopar so I can't comment on the aftermarket of that.

 

Wow. Do you mind if I copy and share your post with a few friends?

 

Wow! I thought mine were bad.... my 2011 is new to me and has about 170K on it. I thought it best to change the plugs as I don't really know the history. Mine are, generally, between your first and third as far as appearance. Gap is huge and the ground is very thin/sharp at the end. Thanks for sharing.

Oil and filter done; next up is coolant flush.

 

I changed ours on our 2009 JK with 175K on it. They looked very similar to yours. We had some rough idle but nothing that indicated they were that bad. I replaced wires and plugs along with both O2 sensors at this point. Most work done on the jeep since we bought it new other than oil and filters every 3K.