Recommendations for coil packs / tune-up parts

JKLNHYD

JKLNHYD

TJ Enthusiast
Joined
Oct 22, 2019
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130
Location
Long Beach, MS
Finally getting around to do a much needed general tune up and I need some opinions. Seems that NGK plugs are the preferred plugs so I was going to go with those and in the process of replacing them, I figured I would do the coil pack at the same time just to be in it once and done.

The coil pack prices are all over the place though. From $100 to almost $300. NGK has one for $144 but I'm curious if I need to spend the coin for the Mopar one at $250. Is there any noticeable performance differences? Reliability differences?

I'll replace the air filter as well but what else is recommended? O2 sensors?

The Jeep runs pretty decent for 184K miles so it's more piece of mind than anything else.

Thanks in advance...
 
I don't necessarily agree that NGK plugs are the best "go to" brand even though there's a sticker with NGK's name on it in the engine compartment. The very best performing and longest lasting plug I'm aware of that works well with your coil rail ignition system is the Autolite XP-985 iridium tipped plug good for 200k miles, followed by the 100k mile platinum Autolite APP-985 (NOT the AP-985!) and Champion 7412.

The coil rail ignition system is very fussy about what spark plug it will work well on. The XP-985 and APP-985 are especially well proven on that engine.

If you absolutely want to go NGK at least insure if you get platinum that the platinum coating is on BOTH sides of the gap, some only have it on one side of the gap which will cause misfires and a bad idle on the 4.0 engine that has the coil rail ignition system as yours does.
 
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The dodge caravan has a coil pack that is 6 plugs too, just need the conversion harness for power and 6 good plug wires. I posted on it a while back. Some like it and others like the cop. Tim
 
I have had excellent results using E3 sparkplugs in everything from log splitters to tractors to trucks.
I'm planning on trying them out on my 06 TJR this summer. Does anyone have experience using these in the 4.0 engine? Or am I going to be the first?
 
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Yes I have. And it seems to say the e3 has an extremely tiny edge on the others. Again, every engine is different, but I have had good results with them in every application I have used them in. Especially chainsaws. Possibly due to 2 stroke engine. So I guess I'll give them a go, since I can't find anything saying they would be worse than any other type/brand.
 
I installed the NGK coil rail about 2 years ago. Worked perfectly and has been flawless so far. NGK is my preferred spark plug brand, so I already had trust in the brand. My second favorite plug brand is Autolite.
 
Jerry Bransford said:
Junk science, it's a gimmick spark plug.
Click to expand...
While I generally agree with everything you say, these plugs definitely improved my small 2 stroke and air cooled 4 stroke engines. Improvement on bigger engines is questionable, but definitely better than using a Champion piece of crap plug. So while I agree their hype seems over rated in larger engines, I've never had any problems from them either. I can't say that about 💩Champions, or even NKG.
But I've also never had to deal with an engine that appears so temperamental as this TJ apparently is.
Curious why the 4.0 is so picky about everything. The 4.2 and even the 4.0 in a YJ never seemed to have replacement parts so specific.
 
Goatman said:
But I've also never had to deal with an engine that appears so temperamental as this TJ apparently is.
Curious why the 4.0 is so picky about everything. The 4.2 and even the 4.0 in a YJ never seemed to have replacement parts so specific.
Click to expand...
It's not the 4.0 that is fussy, it's the waste spark ignition system design used on 2000 and newer 4.0 engines that is fussy. Waste spark ignition systems, which those with the coi rail have, fire the plug every stroke and with alternating polarity spark, first one direction then the opposite direction across the spark plug gap. Basically the spark plug needs the same material on both sides of the gap. Which is why single-tipped platinum plugs like the Autolite AP-985 and Champion 3034 lugs don't work well, they only have the platinum coating on one side of the gap. But double-tipped platinum plugs like the Autolite APP-985 and Champion 7412 are good choices since they have the platinum coating on both sides of the gap which is required by the waste-spark design. Or conventional plugs or iridium-tipped like the Autolite XP-985. The type to avoid with a waste-spark ignition system is simply single-tipped platinum plugs like the Autolite AP-985 or Champion 3034.

E-3 spark plugs work ok in some engines but their hype and claims of how they work is absolute pure junk science. Their claims of what makes them "better" are laughable by anyone who understands how spark plugs really work, how spark travels, and ignition system design. They don't last as long and their construction is not as good as the mainstream brands. E-3's spark plug is the Tornado air intake of spark plugs and modern-day equivalent to snake oil.

snake-oil.jpg


Better quality plugs from companies like Autolite, Champion, NGK, etc. will always be a better choice than junk science snake-oil products like from E-3.
 
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While I agree they do not meet their marketing claims, I have met few products that do. I had first tried them in a chain saw as they were the only brand the local Mom & Pop carry (tired of angry people with week old Champion plug in hand.) And for me they worked well. I'm not claiming them superior to other brands (except Champion) and wouldn't expect them to last like a platinum or iridium. Guess I'm mostly just curious to see how they do when many others seem to fall short. Give you an update after I get some hours on them. Thank you for suspicious pessimism. Not enough people do that anymore. 👍
 
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Little update here. So I went with the XP-985 plugs recommended above by Jerry. I also decided to wait on the actual coil rail until after I did the plugs to see what kind of difference just changing plugs would make.

When I started removing the plugs that were in it, they were barely tight! :oops: I almost could have removed them just using the socket and extension like a screwdriver. Pulling the first out, it was a Bosch platinum (shown below).
Bosch Platinum.jpg

I am not sure how long they had been in the Jeep and they didn't look overly burnt but I was going to change them regardless. I installed the new plugs, torquing them to the required 26-30 ft.lbs and reinstalled the rail. Upon starting the Jeep, I immediately could tell by the sound that they were an improvement. Driving the jeep, I also felt what was almost like a new engine. It revved butter smooth and was 100% more responsive than before. I'm curious if I would see any additional improvement by changing the rail. With 184K miles, I believe it's more insurance than anything at this point but I could be wrong.

While I was under the hood, I found what is likely a valve cover gasket leak, until I checked the bolts and found those barely tight, as well. Snugged them down and sprayed the engine down with Simple Green and lightly hosed everything off.

I cleaned the K&N air filter but I'm hesitant to put it back in. I had bought a cheap air filter to replace the K&N during cleaning but with it running as strong as it does now, I'm not 100% sure the K&N wasn't holding some airflow back. What's everyone's thought on washable filters?
 
They are'filters" that don't really filter. They allow a LOT of particles into the engine. Put back to stock filter and keep a good frame filter and get better filtration. The 4.0 does not have a restrictive filter system. So that "improved air flow" does not exist until you do some serious head and exhaust work first. Stick a horoscope down the intake runners and I'll bet you find a whole lot of filth.
 
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Goatman said:
They are'filters" that don't really filter. They allow a LOT of particles into the engine. Put back to stock filter and keep a good frame filter and get better filtration. The 4.0 does not have a restrictive filter system. So that "improved air flow" does not exist until you do some serious head and exhaust work first. Stick a horoscope down the intake runners and I'll bet you find a whole lot of filth.
Click to expand...

That confirms what I was already thinking about not reinstalling the K&N.

On an unrelated note, you're from Upstate NY? I was born and raised in Lockport!
 
I'm in the same process right now... after being in trouble twice the same week (one because of the trans shifter bushing popped out, another because battery wiring was a mess and dirty) been thinking on doing a tune-up as well although I'm not really sure what that exactly means.

I got my '06 TJ a couple of years ago with around 105k miles on it, its going to 120k. I've done a lot of work on it from every part I thought was critical at that point as it was in a pretty bad shape when I got it and the former owner is known to be careless. Whole cooling, AC, hoses, suspension, brakes, etc. changed.

So anyway, I've done the usual oil/gaskets/filters stuff as needed but I was thinking on changing the main wiring as it is pretty worn and the spark plugs once I'm in that process which then took me to the rabbit hole of what else should I change for the peace of mind the rail as JKLNHYD says.

So my idea is to do an electrical/ignition tune up, again, don't want to have trouble down the road plus this is my daily driver:

  1. Custom battery cables from this guy who does specifically that
  2. The Autolite XPXP985 spark plugs as they seem to be the recommended option in so many threads if you have the coil rail
  3. Ignition coil rail, there's a cheap Duralast one on autozone for around $75, then there's the mopar for $200. I usually don't cheap out on critical parts so if there really is a difference I rather have the OEM but if its just the name then it's a waste of money of course
  4. Upstream oxygen sensor, there's this one on Amazon, a Bosch, $35, but I've heard they are not the best sensors for jeeps
  5. Downstream oxygen sensor, again, a Bosch, in Amazon, $45
  6. Injectors?, There's these remanufactured which are 4-port from ksuspensionfab which seems to be popular in these forums, around $115 bucks

Of course #1 and #2 would be the basics, the other's are just things I'm kinda inclined to do as well while I'm at it.

I just saw a guy today doing a tune-up on his TJ on youtube that went as far as changing all sensors in the throttle body... not sure if that is even required either. I have no codes thankfully but I do feel that a 15 year old car definitely can broke down on worn parts or those which are supposed to do anytime.

This is my second jeep, I used to own an XJ but really I've been learning with the TJ recently so bear with me if these are just too many questions/points 😅 I rather start doing myself these things now than to take it to a shop unless it's something really complex.
 
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