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Better Late than never...

1338 Views 15 Replies 10 Participants Last post by  TheBoogieman
I changed the factory spark plugs at 115,000 miles today, if someone tells you that you don't have to change the spark plugs on newer vehicles these days till after 100,000 miles, punch them in the face.

I should have known better, but it is what it is. The factory service manual says to replace them at 30,000 miles with NGK ZFR5N 3459 plugs. My 2005 LJ Unlimited 4.0 Spark gap should be .030 to .035, the ones I took out were nearly triple that.

On the upside, the Jeep seems to be running great, now for a road test to see what the mileage will be now.

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· Disturbed Jeepaholic
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42,512 Posts
100,000 miles for the double platinum plugs that you should be running in your Jeep. Those old NGK plugs are crap. Autolite APP985 plugs are all I run in mine.

p.s. Your "newer vehicle" is 11 years old.
 

· Retired Staff
2004 Jeep Wrangler
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76,767 Posts
Wrangler TJs came with conventional spark plugs, they're only good for maybe 35K miles. Switching to Autolite's APP985 or Champion's 7034 would give you an honest 100k miles of good performance from their platinum coatings. Autolite's XP-985 is iridium coated and it'll give closer to 200k miles of good performance.

Be wary of other spark plugs, many plugs that are supposedly proper for your 2005 are in reality not. Like make sure to avoid Autolite's AP985 or Champion's 3034 which show up as correct for all Wrangler TJs but they're not correct for the newer models that don't use distributors.
 

· Registered
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8 Posts
Discussion Starter · #5 ·
Wrangler TJs came with conventional spark plugs, they're only good for maybe 35K miles. Switching to Autolite's APP985 or Champion's 7034 would give you an honest 100k miles of good performance from their platinum coatings. Autolite's XP-985 is iridium coated and it'll give closer to 200k miles of good performance.

Be wary of other spark plugs, many plugs that are supposedly proper for your 2005 are in reality not. Like make sure to avoid Autolite's AP985 or Champion's 3034 which show up as correct for all Wrangler TJs but they're not correct for the newer models that don't use distributors.
Thanks Jerry, I'll put that on the list for down the road. Considering I went almost 4 times as long as recommended, I've been lucky. I considered the Iridium plugs, but wasn't sure if they were compatible with my 05 Jeep. The forums tend to be all over the map when it comes to which plugs to use, and it gets hard to cipher all the info on specific year models when a lot of the guys are generalizing the information.
 

· Premium Member
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10,413 Posts
A little wire brushing and regapping and you might could go another 100k!

Post up what you mpg is on your next tank of gas.
 

· Registered
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584 Posts
i am running the factory NGK plugs . removed NGK, installed NGK (replaced at 60 000 kms) they work well. i have been using them for 65 000 kms (40 000 miles).........i have no reason to change them other than curiosity ? maybe i'm missing out on something way better ? but if the fella here got 100 000 miles on NGK , they can t be that bad eh ?

good luck with what ever brand you run.

i might have to try a set of champs just to see.....

2004 tj with 125 000 kms
 

· Registered
Joined
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8 Posts
Discussion Starter · #11 ·
Do you gap them all to factory specs? Just got a 97 tj 4.0 and want to change them this weekend.
Yeah, i gapped them to about .033 i figure it was the happy medium between the suggested .030 to .035

Jeep is running great, picked up about 3 mpg, I was averaging 13 mpg with a mix between city and hwy miles, now getting 16.

I'll go with the iridium plugs in 30k miles, I trust Jerry's suggestion's and would have put them in this time had I known they would work well with my year model.
 

· R.I.P. Knuckelhead
Joined
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23,203 Posts
Wrangler TJs came with conventional spark plugs, they're only good for maybe 35K miles. Switching to Autolite's APP985 or Champion's 7034 would give you an honest 100k miles of good performance from their platinum coatings. Autolite's XP-985 is iridium coated and it'll give closer to 200k miles of good performance.

Be wary of other spark plugs, many plugs that are supposedly proper for your 2005 are in reality not. Like make sure to avoid Autolite's AP985 or Champion's 3034 which show up as correct for all Wrangler TJs but they're not correct for the newer models that don't use distributors.
Truth in this post and its good advice.
When I removed the OEM spark plugs at 32,000 miles the plugs were at about .050". Installed the Champion 7034 plugs and checked them 30,000 miles later about 10 years, still at .035 as I had set them. It now has 75,000 miles on it and has never had a hiccup... HTH
 
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