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Old 05-20-2011, 01:03 PM   #1
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Spark plugs...Please help.

I know this seems to be a bit of a touchy subject here. But I have a 2003 Wrangler with 4.0 and the distributorless ignition system and I need to know what spark plugs I should put in. I have read that they can be tempermental if the wrong plugs are put in so I want to make sure I put the right ones in it. My dad was listening to it the other day and said it has a miss in it and I need to change my plugs. So I am hoping that this fixes the problem. I am on a budget so iridium plugs are most likely out.

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Old 05-20-2011, 01:12 PM   #2
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Jeep built the engine, Jeep built the ignition system, Jeep also put the recommended plug type, brand, and number on the underhood label.

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Old 05-20-2011, 01:21 PM   #3
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There will be many recommendations here. I just go OEM.
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Old 05-20-2011, 01:48 PM   #4
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This should answer your question.

http://www.wranglerforum.com/f5/best...0-a-92914.html
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Old 05-20-2011, 02:07 PM   #5
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Thank you doclouie. rrich, Jeep built or put everything on your Jeep. Are you never going to upgrade your tires, suspension or anything else with better aftermarket parts?
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Old 05-20-2011, 02:18 PM   #6
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Go with what Jerry Bransford says:
Quote:
The 2000 and newer 4.0L is indeed very picky about the spark plugs it runs on due to its DIS (distributorless ignition system). It fires on both the compression and exhaust stroke which places additional demands on the spark plugs.

Because the spark plugs fire twice as often with a DIS-equipped 4.0L engine, conventional spark plugs like the NGKs a few keep recommending will only last half as long in the newer DIS engines as they would in an older non-DIS engine. Personally, I would only run dual-tipped platinum like the Autolite APP-985 or Champion 7034 or the new iridium style spark plugs like Autolite's XP-985 in newer DIS engines.
I went with the Autolite's XP-985 iridium plugs and they work great.
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Old 05-20-2011, 05:56 PM   #7
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"""""Thank you doclouie. rrich, Jeep built or put everything on your Jeep. Are you never going to upgrade your tires, suspension or anything else with better aftermarket parts?"""""

What an intelligent statement!


When you upgrade tire size, it leads to upgrading suspension. Upgrading the suspension leads to modifying the drive line --- and so on.

But screwing in plugs that have been proven time and time again not to work just because the parts kid makes a commission doesn't mean it's better than what the engine was designed to use.

Unless of course, you have already modified the combustion chamber's shape, compression ratio, use differently crowned pistons, changed valve lift, valve timing and duration, and use a different ignition system.
Of course you have done these!
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Old 05-20-2011, 06:35 PM   #8
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The only plugs my Jeep seems to run right on are the NGK's. Tried the bosh things first (before I knew better) with like 12 electrodes, jeep would barely stay running. Then went to some other platinum plug, better but still missed. Put in new ngk's and never had a problem again.
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Old 05-20-2011, 06:58 PM   #9
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Quote:
Originally Posted by MikesX2003 View Post
I know this seems to be a bit of a touchy subject here. But I have a 2003 Wrangler with 4.0 and the distributorless ignition system and I need to know what spark plugs I should put in. I have read that they can be tempermental if the wrong plugs are put in so I want to make sure I put the right ones in it. My dad was listening to it the other day and said it has a miss in it and I need to change my plugs. So I am hoping that this fixes the problem. I am on a budget so iridium plugs are most likely out.
It's real hard to beat plugs that run well for 100K miles instead of the OE plugs that are lucky to see 25K miles before excessive plug gap erosion begins on the current (2000 and newer) DIS (distributorless ignition system) 4.0L engines.

For 2000 and newer 4.0L engines, all of which are DIS style engines, the Autolite APP-985, Champion 7034, and Autolite XP-985 are superb plugs that will run well for >100,000 miles without the spark plug gap erosion as you'll get with a conventional plug like the factory installed that will get maybe 25K miles before that problem starts.
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Old 05-20-2011, 07:30 PM   #10
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That's what I was thinking Jerry. Like you said in a previous post, "The 2000 and newer 4.0 fires on both the compression and exhaust stroke which places additional demands on the spark plugs"
Followed by "Because the spark plugs fire twice as often with a DIS-equipped 4.0L engine, conventional spark plugs like the NGKs a few keep recommending will only last half as long in the newer DIS engines as they would in an older non-DIS engine."

I was looking into these other types of plugs and trying to get the most for my money. But I guess because I haven't done any major engine mods it doesn't make much sense... At least according to some...
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Old 05-22-2011, 05:07 PM   #11
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Case in point: My Jeep has 45,000 miles on her and I just decided to replace the plugs today. Should have been done long ago. I haven't been having any problems and she's run well, but every so often I got the impression that all wasn't right. The original NGK plugs were in there. I inspected and checked the gap on each when I removed them. The gap ranged from .053" to .062". I gapped my new Champion 7034 plugs to .035". The engine purrs now. Never going back to NGK...but that's just me.

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