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Spark plug question .

4771 Views 26 Replies 14 Participants Last post by  AzTJ
I'm new to Jeeps , what's plug do y'all use . I have a 98 tj 4.0 , fsm says to use rc12lyc , i'd like to change plugs today if it ever stops raining :D Comments ?
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i run the just plain ol' autolite plugs and have had no problems. i've run the more expensive bosch plugs and didn't notice any difference. alot of guys suggest champion truck plugs. it seems jeep motors prefer the simple plugs to all the expensive stuffs.
Champion Truck plugs are commonly recommended but I get the same good performance with Autolite's single-tipped platinum (platinum on just one side of the gap) coated plugs that easily outlast the Champion non-platinum Truck Plugs by 3-4X. Double-tipped platinum plugs (platinum on both sides of the gap) have no advantage over single-tipped platinum plugs where the older 4.0L engines go that still have a distributor.
Plain ol' Autolite's here as well.....have never noticed any differnce in the past with the more expensive plugs.
I use the Champion 4412 plugs with good results
any one run platinum +4 (4 prongs)? Any luck or comments?
I wouldn't run those unless you have coil packs or a high energy igintion system...

I run Bosch Platimun plugs, love'em!
there was a demo in my local auto store of those vs regular plugs.. i love how those make 4 sparks compared to the 1 regular spark.. also it showed that they require less voltage to jump since there is more surface area for the spark to jump to.

Thanks AzTJ :)

Keep them coming :)
champion copper plugs, mopar motors love champions
Ac Delco
I ran the +4's for about 6 months now. I run these plugs in truck and i was impressed with them. ON the Jeep though it has been a different story. I started having a random idle...jumping from 450-1200 rpm and figured it was tps, AIC, or some other nonsense. After changing everything i decided to change the plugs over to champion. Pulling the bosch ones out i was suprised after 6 months they were completely fouled. After the champions went in it idled as smooth as ever. I did a lil research and several people say the coil packs dont generate enough power to efficiently spark the +4s. Guys with the distributor may not have this problem but they didnt do well in my jeep. I torture mine and put it through hell keep in mind, but jus figured i would share this with ya.
I installed NGKs a few weeks ago and they seem fine so far. I think the TJ had the original Champions in it you could throw a cat thru the gap and they were burned up. It has 77,000 miles on it.
i have the +4's for i'd say atleast 3+ months now with no problems. I've ran 2 cans of seafoam past them too without issues. i was extreamly impressed when i first put them in, but my next set will be the E3's i think. the +4's are the only set i've tried so far, but ill give a comparison as soon as i need to change them again.
oooo the E3s look sexy :) too bad thats the first time i heard of them.. ill take a look when i go to my local auto store Do you still have to set the gap when you get +4? They do look like they are not set.
Do you still have to set the gap when you get +4? They do look like they are not set.
No - they are preset and should not need to be gapped, because there really isn't a good way to. Usually the guys at the auto part stores are trying to BS you into buying them for the higher price. I'm gonna try them E-3's when its tune up time. But anything "platimun" should be fine. I'm also thinking of getting an MSD Blaster Coil and bigger 9-10mm wires for the hell of it.
which MSD blaster coil (#?) is for Jeep TJ's? is it a universal part because neither summitracing nor quadratec had the actual blaster listed for TJ's
well keep us updated with what you do since i'm also interested if msd coil will make such of a difference vs the stock unit:)
which MSD blaster coil (#?) is for Jeep TJ's? is it a universal part because neither summitracing nor quadratec had the actual blaster listed for TJ's
MSD #8228 - I know it will work for '97 TJ's with 4.0L but I don't know about '98-Up. AutoZone and maybe Checker cary them in stock, so you might be able to go there and check one out first hand to see if it would fit. Accel does have a coil that is listed for 91-99 YJ/TJ - LINKY, but 98-99 will need an adapter for it to work... I think it has to do with the input pins to the coil itself, either 1 or 2. But I'm going to be getting the MSD 8.5mm wires when I upgrade the coild and plugs.
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