What are the best spark plugs for my Jeep Wrangler TJ 4.0?
- Thread starter Jerry Bransford
- Start date
They really can't be beat for about a buck a plug with rebate and discount.
Autolight has a rebate on plugs thru the end of 2020.
Save $3.00 per plug on the XP plugs.
https://www.autolite.com/docs/default-source/default-document-library/2020-autolite-rebate-flyer.pdf
Save $3.00 per plug on the XP plugs.
https://www.autolite.com/docs/default-source/default-document-library/2020-autolite-rebate-flyer.pdf
I replaced mine with the Autolite Iridium plugs 2 years ago. I haven't missed a single start since. Mileage performance is nearly spot on factory standards. I haven't bothered to pull'em to see the wear. If what Jerry's friend said is true, I expect at least 100k or more out of these before I change'm out.
Believe me, you probably won't have to worry about the plugs for a long time. I'm going to pull a few out in another 20k miles and see their appearance. If they look brand new, the screw it, I'll leave'm go for at least another 50k maybe 75k before checking again.
The whole controversy on plugs and materials etc... gets a little weird sometimes. Honestly, if you're not boosting the motor and it is just naturally aspirated, iridium and double platinum may be overdoing it, unless you just don't like changing plugs every 20k-30k miles.
I went with the NGK ZFR5N plugs as recommended from previous posts and the motor just feels different. In a good way.
I went with the NGK ZFR5N plugs as recommended from previous posts and the motor just feels different. In a good way.
The Goblin
Member
I just replaced mine with the Champion double-platinums and I had to gap them for sure. The instructions said they must be gapped and I can see why because the factory gap was HUGE. I gapped them down and measured with a feeler gauge.
However, on my Volvo, I just bought a bunch of NGK plugs and the instructions there say NOT to gap, and if necessary, don't do more than .008" (as was previously mentioned).
Also, the NGK website says NEVER to use anti-seize on the threads because it can act as a lubricant and can actually change the torque by up to 20%, which can lead to broken threads and issues with proper distance, etc.
So I think the point is, whatever you buy, read the instructions.
Thanks for the thread! Tons of help here!
However, on my Volvo, I just bought a bunch of NGK plugs and the instructions there say NOT to gap, and if necessary, don't do more than .008" (as was previously mentioned).
Also, the NGK website says NEVER to use anti-seize on the threads because it can act as a lubricant and can actually change the torque by up to 20%, which can lead to broken threads and issues with proper distance, etc.
So I think the point is, whatever you buy, read the instructions.
Thanks for the thread! Tons of help here!
I just changed the NGK's on my recently purchased 05 with the XP-985 (iridium) plugs and she's running great! Be sure to get the rebate posted above. I also used anti-seize, just in case, and checked the gaps, just in case, and actually found a couple that weren't quite right. Be sure to use the right kind of gap gauge tool (not the old coin style). I picked up one like this:
https://www.oreillyauto.com/detail/...3681/2005/jeep/wrangler?q=feeler+gauges&pos=8
Here's another link that helped with checking\adjusting the gap as well:
https://www.oreillyauto.com/detail/...3681/2005/jeep/wrangler?q=feeler+gauges&pos=8
Here's another link that helped with checking\adjusting the gap as well:
TJ2
TJ Expert
Interesting...I know there has been a lot of debate on this, and I'm certainly not wanting to start another one, but it seems like a lot of people have had good success with the XP-985 (iridium) plugs and are the most recommended. I was honestly going back and forth between just getting the stock NGK's and the XP-985's. Any specific issues I should be looking out for with the iridium plugs?
I recently bought my TJ with 37k miles on it and it looked like the original plugs were still in it so even though it was running good it was time for them to be changed. There was a very slight\subtle rough idle that I was hoping the new plugs and cleaning the IAC would resolve, but unfortunately they didn't. I wonder if the stock NGK's would make a difference with that? I also haven't gone a full tank yet with the new plugs so not sure if it's affected gas mileage like someone suggested earlier.
I recently bought my TJ with 37k miles on it and it looked like the original plugs were still in it so even though it was running good it was time for them to be changed. There was a very slight\subtle rough idle that I was hoping the new plugs and cleaning the IAC would resolve, but unfortunately they didn't. I wonder if the stock NGK's would make a difference with that? I also haven't gone a full tank yet with the new plugs so not sure if it's affected gas mileage like someone suggested earlier.
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Greetings all, hope everyone is doing well....working through a new to me TJ. It has been sitting awhile, like 700 miles in the last year, until I acquired last week...she is not happy right now and I have to resolve that!!
APP985 or XP 985? I see recommendations for both? Thanks in advance!!! (gapped to .040 right Jerry?)
2005 Rubicon
APP985 or XP 985? I see recommendations for both? Thanks in advance!!! (gapped to .040 right Jerry?)
2005 Rubicon
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OP
Either of those gapped to .040 would be fine for your newer TJ. The iridium XP-985 will just outlast the APP-985 by about 100k miles to get no less than 200k miles or wear.
Make sure to not use a tapered style spark plug gapping tool on iridium or platinum plugs, they'll damage the coating. Use the type with the gapping tool that bends the electrode, like this one has on the left-hand side.
Just added the xp 985 to my amazon cart for $6.38. Will be tackling these after I take it to the shop and have the rear main seal replaced. Thanks again for all the helpful information on this site!
So got the plugs replaced this evening. They were also the XP, but the gaps seemed all over the place. Some were.040 some were .035, two were .025. Look pretty lean? View attachment 224156 I guess we'll see when I get the rest of the work done, waiting on a ODPA. Question though, is it necessary to use anti-seize on the coil bar bolts? Thanks!!
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OP
No antiseize needed for the coil rail bolts. If by that you're planning to put antiseize on the plug threads, use the smallest amount possible and make sure none can make its way to the electrode. Antiseize is conductive.
Look pretty lean? Im also tracking down elevated RPM when clutch is engaged when driving, it also had a run-on high idle the other day...ODPA going in, cant find a mopar sensor (discontinued), so its gonna be a Echlin. Going to clean the TB and idle control, maybe replace the O2s......hopefully these will solve it...Jeep was sitting for a long time...Lots of work to do still