2009 rubicon threw a code. P0302. Cylinder #2 misfire. Removed plug and it was really worn down. The gap was huge! Regaped the old plug and stuck it back in. Runs good. Code gone. When I was in the dealer last week for oil service I had asked about replacing plugs and he said it was not due yet. 57000 miles. Really? I wanna do them myself but cylinders 3 and 5 look like a bitch!!! Anybody have any tips? Remove battery perhaps? Thanks

 

I went with the Bosh Iridium ones after getting a misfire code. Great plugs, not cheap. Not too hard to do yourself, my tips:
Have several socket extensions including at least one uni joint
A bit of tape or heat shrink around the uni joint will stiffen it up so it does not flop around when guiding a plug
Start the plugs by hand- do not risk cross threading!
Do not over tighten plugs
You may find the passenger side rear plug is actually easier to get to from below
Get stuck in and have fun

 

Denso PK20TT are what I went with. Factory manual says 100k miles but I'm with you at 50k change.

It's not a popular option, but I pulled my entire flare and liner from the right side to change my plugs. I've pulled that flare quite a few times so it doesn't intimidate me.

 

100K miles is fine for plug replacement unless you have a problem--these are quite literally not your dad's plugs. I changed mine at about 92K and they all were in reasonable shape (changed because I was putting in dual-battery tray so it just made sense). The change resulted in no difference in performance or gas mileage. As for the gap, the reason we don't pull plugs and regap them is because the engineers take plug gap increase into account when they design a vehicle.

 

I thought I had written a thread on my plug replacement experience but can't find it. Some points that I remember. Fold the hood all the way back to the roof. I know that seems logical but I didn't think about it until I hit my head a few times...duh. Next be sure to put a small amount of silicone grease in the plug boot to aid in future removal. Be easy on plug boot removal. Twist/rotate the boots before pulling them from the plugs. Put a small amount of anti seize on the new plug threads. As I remember, the passenger firewall plug was the most difficult to remove...do it first and get it out of the way. I used the OEM Champions that are recommended. I found a full set of 6 on eBay. Good luck. BTW, I'd never go to 100k mi because of the risk of the difficulty in getting plugs out at that mileage/time and the plug boots really getting stuck on the plug. Be extra careful in ensuring the plug wires are placed/replaced in the wire guides as they were when originally installed. Take a photo of how the wires were before removing them. BTW the plug wires are numbered to match each cylinder.

 

How often should I change out the plugs then? I was going to wait but if new plugs would increase performance of mpg then im all for doing it early

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You won't see any performance or MPG increase unless yours are terribly dirty or fouled. You can go with the factory spec of 100k or whenever you would like to. I did 50k, but I'm on the "old school" maintenance schedule (3k oil changes and all).

 

Use stock Champion plugs gapped at .050

 

Do not use e3's they are junk !!!!!


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Mine were shot at 60k.