What are the best spark plugs for my Jeep Wrangler TJ 4.0?

[LJ-MXer]

Not yet registered but does anyone have any experience with the latest NGK Laser series plugs.

Side note: is NGK/NKG still the top alternative to Mopar for sensor i.e. CPS, IAC, TC?
Thanks I'm advance!
06 LJ 6sp SW Fl

 

[LJ owner]

Somewhat confusing. For a 1997 4.0L TJ What plug is the best ?

The Champion 7412 does not show it is available. The Autolite plugs are.

 

[Foxgluv]

For a '97 4.0L TJ is there any difference between regular Platinum (AP-985) or dual-tipped Platinum (APP-985)?

 

[tr21triton]

I run XP985's in both my 97 and 05 4.0's

 

[Mr. Bills]

For a '97 4.0L TJ is there any difference between regular Platinum (AP-985) or dual-tipped Platinum (APP-985)?

An AP-985 plug has a platinum electrode; an APP-985 plug has a double platinum electrode.

Neither plug will make your engine run better or smoother than the factory specified NGK ZFR5N spark plugs. Platinum electrodes last longer; double platinum are reported to last even longer. However, TJ plugs are so easy to change there is little point. Do you really want to go 100,000 miles without checking the condition of your plugs, re-gapping, etc. If I'm going to pull the plugs to re-gap, I might as well replace them. I use the factory specified NGK ZFR5N plugs and replace them at the factory recommended 30,000 service interval. Since my jeep is a toy, that works out to once every 5 years.


Autolite AP-985 x 6 at O'Reillys = $29.94
NGK ZFR5N x 6 at O'Reillys = $32.94
Autolite APP-985 x 6 at O'Reillys = $41.94

 

[Foxgluv]

An AP-985 plug has a platinum electrode; an APP-985 plug has a double platinum electrode.

Neither plug will make your engine run better or smoother than the factory specified NGK ZFR5N spark plugs. Platinum electrodes last longer; double platinum are reported to last even longer. However, TJ plugs are so easy to change there is little point. Do you really want to go 100,000 miles without checking the condition of your plugs, re-gapping, etc. If I'm going to pull the plugs to re-gap, I might as well replace them. I use the factory specified NGK ZFR5N plugs and replace them at the factory recommended 30,000 service interval. Since my jeep is a toy, that works out to once every 5 years.


Autolite AP-985 x 6 at O'Reillys = $29.94
NGK ZFR5N x 6 at O'Reillys = $32.94
Autolite APP-985 x 6 at O'Reillys = $41.94

I agree with pulling the plugs every 30k to check on them, but why not get the AP-985 if they last longer and are cheaper than the NGK's?

My main question is if the Platinum (AP) and Double-Platinum (APP) are both fine for the '97. I understand newer TJ's need the APP, but people seem to go back and forth on the Platinum vs Double-Platinum for the older TJ's. If the AP is fine, then is seems like it would be the best cost option for my '97.

 

[MikeE024]

An AP-985 plug has a platinum electrode; an APP-985 plug has a double platinum electrode.

Neither plug will make your engine run better or smoother than the factory specified NGK ZFR5N spark plugs. Platinum electrodes last longer; double platinum are reported to last even longer. However, TJ plugs are so easy to change there is little point. Do you really want to go 100,000 miles without checking the condition of your plugs, re-gapping, etc. If I'm going to pull the plugs to re-gap, I might as well replace them. I use the factory specified NGK ZFR5N plugs and replace them at the factory recommended 30,000 service interval. Since my jeep is a toy, that works out to once every 5 years.


Autolite AP-985 x 6 at O'Reillys = $29.94
NGK ZFR5N x 6 at O'Reillys = $32.94
Autolite APP-985 x 6 at O'Reillys = $41.94

I feel the same way about leaving plugs in that long. I’m running the nickel/copper NGK plugs (likely what you listed) and don’t mind changing them at the service interval.

I pulled the iridium plugs while troubleshooting a misfire that ended up being a bad PCM. There is no difference in performance.

 

[pbeach]

2.4L — been running Autolite Iridium XPs. Love 'em. Zero issues.

XP5263 — https://tinyurl.com/yt285wce

 

[Pantera99]

Hey all, reading through this thread & it just dawned on me despite all the minor problems over the years I haven't touched the plugs in probably 70k miles. I believe I went with Champion double platinums. Running very well, I've just noticed even when brand new she takes a bit to get started. Wondering if Iridiums are worth a try? My experience with Autolite plugs has always been terrible however. Or considering just regular coppers. '02 4.0L, 155k miles.
Just threw a downstream O2 sensor code, but I believe they're still originals. Have changed upstream already. Thoughts?

 

[Mr. Bills]

. . . Wondering if Iridiums are worth a try. . . ?

The only advantage to iridium plugs over platinum plugs is longevity, not performance. [I'm talking about manufacturers' claims of longevity, not the ridiculous claims of our "no longer participating" member @Jerry Bransford .]

Do you really need spark plugs that will last a decade for an engine with such easy access for replacement?

I use the factory specified NGK ZFR5N spark plugs and change them at the factory recommended 30,000 miles. No starting issues; no performance issues; no issues at all.

 

[NashvilleTJ]

The only advantage to iridium plugs over platinum plugs is longevity, not performance. [I'm talking about manufacturers' claims of longevity, not the ridiculous claims of our "no longer participating" member @Jerry Bransford .]

Do you really need spark plugs that will last a decade for an engine with such easy access for replacement?

I use the factory specified NGK ZFR5N spark plugs and change them at the factory recommended 30,000 miles. No starting issues; no performance issues; no issues at all.

The main reason I swap mills so often is so I don't have to change plugs...

 

[mrblaine]

Hey all, reading through this thread & it just dawned on me despite all the minor problems over the years I haven't touched the plugs in probably 70k miles. I believe I went with Champion double platinums. Running very well, I've just noticed even when brand new she takes a bit to get started. Wondering if Iridiums are worth a try? My experience with Autolite plugs has always been terrible however. Or considering just regular coppers. '02 4.0L, 155k miles.
Just threw a downstream O2 sensor code, but I believe they're still originals. Have changed upstream already. Thoughts?

Not that it matters since it won't solve your problem but any of the 4 liters with the coil rail are a waste fire system and the service interval is 30,000 miles for plugs. That's because they fire on the exhaust and intake strokes since there are only 3 coils. They reason it won't solve your problem is the coil rail is good to jump a 90 thou gap or almost 3 times factory spec.

 

[Zorba]

Do you really need spark plugs that will last a decade for an engine with such easy access for replacement?

YES!

 

[Steel City 06]

The only advantage to iridium plugs over platinum plugs is longevity, not performance. [I'm talking about manufacturers' claims of longevity, not the ridiculous claims of our "no longer participating" member @Jerry Bransford .]

Do you really need spark plugs that will last a decade for an engine with such easy access for replacement?

I use the factory specified NGK ZFR5N spark plugs and change them at the factory recommended 30,000 miles. No starting issues; no performance issues; no issues at all.

Personally I'd recommend it simply because they're more reliable in the near and mid-term. Less likely to cause issues at the worst possible time.

Also when spark plugs fail or wear out, they can cause much more expensive issues. A spark plug that is worn may not ignite every time. Each time it doesn't, it will send a slug of unburnt fuel and air to the catalytic converter which either ignites and makes the converter very hot (glowing in some cases) or detonates once it hits the catalyst. Either way, it breaks down the converter a lot faster than it should, and the converter is a much more expensive part.

 

[Pantera99]

Personally I'd recommend it simply because they're more reliable in the near and mid-term. Less likely to cause issues at the worst possible time.

Also when spark plugs fail or wear out, they can cause much more expensive issues. A spark plug that is worn may not ignite every time. Each time it doesn't, it will send a slug of unburnt fuel and air to the catalytic converter which either ignites and makes the converter very hot (glowing in some cases) or detonates once it hits the catalyst. Either way, it breaks down the converter a lot faster than it should, and the converter is a much more expensive part.

Yes & I have 2 other older vehicles & 3 bikes & 2 quads plus a pool so I'm always having to monkey with something!!! Id rather use plugs that don't need to be messed with much.
On a side note, from Greensburg myself so looking forward to Sunday night football, hoping Rodgers can make mincemeat of the packers secondary!!
Also happy to see the Penguins starting off on the right foot for once!!

 

[Steel City 06]

Also, not sure if I already mentioned it in this thread, but in addition to the XP985, there is also the XP5405 plug that fits the TJ.

The difference between the two is that the XP5405 is one tier colder than the XP985, so it can withstand more continuous power before it heats up to the point it causes pre-ignition. So for engine that see high load and long durations, it can improve the resistance to detonation and pinging. The caveat is that at lower loads, it runs cooler and is a bit more prone to soot buildup.

So if you drive fairly conservatively and don't often put very heavy loads on the engine, stick with the XP985. If you run higher engine loads (for example, majority freeway or hilly conditions, or frequently towing, or running low RPM at high throttle a lot), the XP5405 would be the best bet. (If you're not pinging much on your current plugs, stick with the XP985.)

Posted about the difference here:
https://wranglertjforum.com/threads/autolite-xp985-vs-autolite-xp5405.54493/

Both plugs are the same long-reach design, just with a different insulator.

 

[MDTJ06]

New here on this forum, but not new to Jeeps or to wrenching. Have an 06 TJ, 114k miles, 4.0/6M. Bought it used at 99k, ran fine, so I just....drove it.

I should know better.

Last winter I was noticing some pinging under load, no matter what gear or RPM. Forgot about it this past summer since the top comes off and hangs in the garage from May or so, until October - and topless, you just don't hear as much mechanical noise. But when I put the top back on for winter....WOW, it really does ping. A LOT. I was chasing fuel issues, thinking "fuel pump" and dreading trying to unbolt a near-20-year-old set of tank bolts (there is no test port on my fuel rail to check pressure). I swapped rails and injectors with my gf's 06 that runs like a champ...still pinged.

Then, I sat and thought. "K.I.S.S." came to mind - Keep It Simple, Stupid. That was when it dawned on me I'd never changed the plugs, or even looked at them - it just....ran. So I was on another forum and got the recommendation for the XP985, so I got a set. Supposedly pregapped to .035" but I checked anyway with feeler gauges - they were about .033 or .034, I had to open them all just a hair...but pretty darn close out of the box. Pulled plugs out of the engine, and WOW. The BEST gap was north of .080", and the worst was over .100"!! Installed the new ones, and what a difference. Power, smoothness, NO PINGING...much happier.

So yes, worn plugs (I think mine may have been the ones it came down the assembly line with) CAN cause problems.

 

[Pantera99]

Ok XP985's on the way, we'll see if they're the greatest thing since sliced bread. Just checked my mileage with the current champion 7034's & right at 17 mpg so they certainly aren't shot but been in the 80-85k miles.
BTW apparently Rock Auto isn't shipping to AZ any longer?? IDK why but I'm sure our stupid Governor Hobbs has something to do with it.

 

[Spike Strip]

Rockauto has an ongoing tax dispute with Arizona. Arizona says rockauto owes them millions in back taxes because third-party distribution centers in Arizona ship parts for RA. Arizona is interpreting that as RockAuto having a brick and mortar footprint in Arizona. RockAuto says, FU, we just won't sell in Arizona anymore.

 

[Pantera99]

Yea I was just researching it. Seems everyone is too happy to screw the average citizen anymore. My buddy was just driving to Tucson & sent me this pic:

Like seriously? But magically gas is all above $3.15+ anywhere in the Phoenix metro area.