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Old 02-14-2012, 09:18 AM   #1
Join Date: Jan 2012
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Spark plugs

Out of all types and vendors of spark plugs.
Does anyone have a good recommendation for specific type and manufacturer for a 93 wrangler 4.0L

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Old 02-14-2012, 09:31 AM   #2
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NGK, the best, no games, no empty promise spark plug.

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Old 02-14-2012, 10:17 AM   #3
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Champon RC12LYC the only plug for the 6L
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Old 02-14-2012, 01:10 PM   #4
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Not sure what is "best" but I pulled Champion RC12LCY plugs out at 83,000 miles and they were the factory originals. They were gapped right at .065" but it was running good. I put in the Bosch 4003 that are gapped at .035.

It does run better, but I also changed wires, cap, rotor and Seafoamed it. Seems like it is going to get better mileage but haven't filled it yet.
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Old 02-14-2012, 05:38 PM   #5
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Jeep spark plugs

Originally Posted by El Toro View Post
Out of all types and vendors of spark plugs.
Does anyone have a good recommendation for specific type and manufacturer for a 93 wrangler 4.0L
I am the tech manager at Autolite spark plugs. If you search this forum, you will find many 4L wrangler owners running Autolite XP985 Iridium spark plugs. I run them in my 97 TJ 4L and they work great. They are by far the best bang for the buck. We have a great price advantage over our nearest competitor mentioned below in the fine wire iridium plug catagory. They are the best technology plugs for your Jeep and will easily last 100k miles. You can learn more about spark plug technology by visiting our Youtube channel and watching the Spark plug anatomy, Spark plug metalurgy and heat range videos. Find it at At the very least, you will be a plug expert regardless of what brand you buy.
We have other ignition system and misfire diagnostic videos there as well. We also have a facebook page that keeps you up to date on our events and new training.
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Old 02-16-2012, 12:30 AM   #6
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Thank you all for the recomendations
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Old 02-16-2012, 08:20 AM   #7
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I don't use anything other than Autolite copper plugs. I've experimented with different brands, high dollar ones, dual high tech yada blah blah ones. The 4.0 runs best on the cheap copper plugs. Anything else and you're wasting money and possibly even degrading performance.

This does *not* apply to other vehicles. I've used platinum and iridium and different plugs on other vehicles and for some there is a benefit. Not on the Jeep 4.0 though.

We are currently away from the forums and unavailable for quotes. Please contact our sales team at 800-388-8637.
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