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Opinions/Experiences on Spark Plugs

3K views 15 replies 8 participants last post by  OlYellerTJ 
#1 ·
Haven't seen a thread like this.

Wanting to get people's opinions/experiences using certain spark plugs.

I personally have an 03 TJ stock plugs and looking to do a tune up.

Post your thoughts below, and let me know the good and bad ones out there!

Thanks in advance
 
#3 ·
You don't say anywhere what your engine is but assuming it's the 4.0L, that engine is distributorless and is thus very fussy about what spark plugs it'll run properly/well on.

The first two plugs are double-tipped platinum which will perform well for about 100k miles.
1) Autolite APP985
2) Champion 7034.

This third plug is iridium tipped and it'll perform well for closer to 200k miles.
3) Autolite XP985.

There are of course other plugs that will run well but the above three are favorites and well proven for newer distributorless 4.0L engines.

AVOID the Champion 3034 or Autolite AP985 even if some guides erroneously list them as correct. Also avoid Bosch Plus-2 or Plus-4, Splitfires, or any gimmick spark plug like those with a capacitor that make all kinds of wild claims.

Don't run ANY single-tipped platinum plugs where the platinum coating is only on one side of the gap, like the Autolite AP985 or Champion 3034 as listed above in the don't run area. Your TJ's ignition system has a "waste spark" and using plugs with dissimilar coatings on either side of the gap will cause problems. :)
 
#4 ·
You don't say anywhere what your engine is but assuming it's the 4.0L, that engine is distributorless and is thus very fussy about what spark plugs it'll run properly/well on. The first two plugs are double-tipped platinum which will perform well for about 100k miles. 1) Autolite APP985 2) Champion 7034. This third plug is iridium tipped and it'll perform well for closer to 200k miles. 3) Autolite XP985. There are of course other plugs that will run well but the above three are favorites and well proven for newer distributorless 4.0L engines. AVOID the Champion 3034 or Autolite AP985 even if some guides erroneously list them as correct. Also avoid Bosch Plus-2 or Plus-4, Splitfires, or any gimmick spark plug like those with a capacitor that make all kinds of wild claims. Don't run ANY single-tipped platinum plugs where the platinum coating is only on one side of the gap, like the Autolite AP985 or Champion 3034 as listed above in the don't run area. Your TJ's ignition system has a "waste spark" and using plugs with dissimilar coatings on either side of the gap will cause problems. :)
I do indeed have a 4.0L sorry for not mentioning it earlier. But thanks for the info very helpful.

I was just texting my buddy on this subject and he said I should be fine not changing them since I only have 30k original miles on my TJ. I was on the side of, well the plugs are 10+ yrs old and my jeeps a lot slower then his is

Just trying to eliminate things with a tune up to see if that helps power wise.
 
#15 ·
+1 on the Champion 7034 plugs.

When I got my TJ, it still had the factory Champion copper plugs and the gaps were ridiculous, I couldn't believe it was running even somewhat well after seeing that. Changed them out with the Champion 7034's per Jerry's recommendation on another post and it really made a difference in how the Jeep ran.
 
#16 ·
I've been very happy running Autolite APP 985 for the last three years. They replaced NGK plugs from the PO.
 
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