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Discussion Starter · #1 ·
Now as you may or may not know, the 3.8L comes factory equipped with Champion RE15PL5 Double Platinum spark plugs. The owners manual states the replacement interval for these plugs is 102,000 miles (p.417). I looked at several different spark plug information sources, most claim a ~60,000 mile interval for double platinum plugs. Why do other sources rate this type of plug at 58% of what Chrysler calls for is beyond me.

Anyway, recently I had been noticing that I needed to slip the clutch a little more to get going. This was much more prevalent the last time I took it out on the trails. As someone who is fairly seasoned with my rig, it usually takes a good bit of load for me to stall it. I stalled it three times within one trail, something wasn't right. The engine was not carrying the load at idle like it should, it was basically shutting off under a decent load..hardly a stumble (even with a 4:1 case).

Comparing my odometer to what the manual stated for my plugs, I figured what the hell and bought a set of plugs. NGKs have been pretty good to me, at $20 for the set...it was worth it. I cleaned the throttle body (for the third time), which was pretty much as clean as you'd want it already and swapped plugs. I went with the single Platinum "G-Power" NGKs (~$3/plug). I didn't care to go back with the double Platinum plugs again, due to the only gain I see is the claimed longer interval. $20 per 30,000 miles or so...is just fine with me. Single Platinum it is.

My mileage bumped up several tenths (according to my inaccurate display, but it is at least consistent). I have gone back to not slipping the clutch as much and it's 4-low loading seems to have improved. I had used the stock plugs to 41% of their rated "lifetime" and saw improvements. That is pretty pathetic (doesn't help that I have never cared for Champion plugs anyway). It took all of ~10-15 mins to swap them out just screwing around.

I am not one to say "go buy new hi-po wires for your minivan engine", today's ignition systems are pretty stellar. However it's pretty sad what Chrysler expects out of these factory plugs, in my opinion. The gap wasn't too bad on the factory plugs (.054" - spec = .050").

These are what the "G-Power" NGKs look like:


Factory plugs; excuse the pictures, I don't have a macro lens!


You can see the leading edge of the electrode has some decent wear on it. Which...shouldn't really happen.
 

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From someone who came from auto parts and has held ASE certification in parts, Champion plugs suck. I had more problems with their insulators and electrodes than any other brand. I really like Bosch plugs. NGKs are good too. Hell, even Allied Signal (Autolite) plugs were superior to the champions. Looks like I will have to swap out those shitty plugs sooner than later.
 

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I am good with NGK but whatever you do don't use E3. The computer just didn't like whatever they do to the engine. I am not saying they don't give great spark but Chrysler computer doesn't know what to do about it. Started missing and throwing codes. Put the stock back in and all good. I need to replace my plugs so this is good info on the NGK.
 

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Good info. I'm going to replace mine with some good NGK plugs. What heat range are the stockers? I'm assuming 5 from the NGK PN on the pic you posted. ?
 

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Discussion Starter · #7 ·
Not sure on the heat range. That is just what NGK calls a replacement plug for the 3.8L


Sent via paper airplane
 

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I've never had a problem with Champion plugs in cars or airplanes.
Can't say I had problems with other brands, either.
I about to replace mine, mostly because they may be welded in if I wait 'til 102K.
 

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Im at 85K and have noticed the clutch requires more slipping as well. Figured it was my clutch, but hell ill give this a try for 20 bucks
 

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I installed Granatelli MPG Plus 0 ohm wires and NGK Iridium IX LZTR5AIX-13 plugs at 61000km or 37 900 miles. I noticed an immediate improvement in starting and idling performance. No change in gas mileage. I also never-seized the threads so I don't have to worry about getting them out later on. I'm at 71000km now or 44 100 miles and still running mint.
 

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Discussion Starter · #13 ·
I don't like to anti-seize the threads, it changes the heat exchange characteristics of the plug. I use a light coat of motor oil.
 

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Thanks for the plug info Goody! I am near my 30k service and plan on changing out my stockers. Saves me from having to search for a replacement.

I tried E3s early on and they were crap. Kept throwing codes and misfiring.
 

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Discussion Starter · #16 ·
Lol, and where did you get this info from?
I am a BMW master technician, this is per their training. A spark plug transfers heat from the cylinder into the threads. You add an insulator to that with antiseize.

And that is where I got that information from. Semi-reputable source, how about you?
 

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I don't like to anti-seize the threads, it changes the heat exchange characteristics of the plug. I use a light coat of motor oil.
If anti-seize changes the heat transfer characteristics, it must have been considered when they chose the plug's heat range.

This is from the factory service manual:
Apply anti-seize compound to spark plug threads only [The illustration shows no anti-seize on the first 4 threads.]
 

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I have a laundry list of things to do this weekend...I'll add plugs to it. I've got 63k miles. It's time.


Sent from me to you
 

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Discussion Starter · #20 ·
If anti-seize changes the heat transfer characteristics, it must have been considered when they chose the plug's heat range.

This is from the factory service manual:
Apply anti-seize compound to spark plug threads only [The illustration shows no anti-seize on the first 4 threads.]
I don't see any signs of it on my factory plug. Anyone can certainly do what they feel.
 
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