[urstolendesire]

Hey guys, this might be on here but I couldent find it anywhere... Arright so I keep hearing that I need to put some "splitfire" plugs into the jeep. "Everyone is telling me the Inline6 loves these plugs and I should see sometype of noticeable difference? The jeep is right at 65,000 miles. I havent pulled any out yet to look, but I'd assume its about time to... Any suggestions?

[LJameson]

If the spark plugs have never been changed, then they're way over due. As far as splitfire in the 4.0 doing wonders, I've never heard that. Just buy Autolites APP985's. Make sure that it's the APP985 and not the AP985. Newer 4.0's don't want that.

[TheBoogieman]

I agree.Go with the Autolite APP985 plugs.

[GEM1N1]

What about the E3 plugs I've seen on Quadratec?

[Jerry Bransford]

Avoid the overpriced gimmick (like E3) plugs, you're paying for hype and no performance gains. And Splitfires are the worst of the bunch, they are a shoddily constructed plug.

For your newer distributorless 4.0L engine, you have to be careful what you install as it's extra-fussy about the plugs it runs on. If it were me, I'd follow the above recommendations and go with the Autolite APP985 which is a first-class quality double-tipped platinium plug. Don't let the parts guy talk you into the AP985 if he doesn't have the APP985 in stock, it won't run well on the AP985. Really, nearly any good quality double-tipped platinum plug like Champion also sells is fine. Just make sure it is DOUBLE-tipped platinum where the platinum is on both sides of the gap.

Or you can run a conventional copper-core spark plug but those don't last more than about 1/3 as long as a good quality platinum plug will.

Edit: Those performance gains quoted by companies like who make the E3 and Splitfire plugs? Yes those are true but only when compared against an old worn out plug, which is how they can make those claims. Bu those claims are not true when compared against a good quality new plug like the Autolite APP985 which is what the newer distributorless 4.0L engines run well with. Or the single-tipped AP985 for older 4.0L engines that have a distributor.

[Jeep25]

Originally Posted by Jerry Bransford

Avoid the overpriced gimmick (like E3) plugs, you're paying for hype and no performance gains. And Splitfires are the worst of the bunch, they are a shoddily constructed plug.

For your newer distributorless 4.0L engine, you have to be careful what you install as it's extra-fussy about the plugs it runs on. If it were me, I'd follow the above recommendations and go with the Autolite APP985 which is a first-class quality double-tipped platinium plug. Don't let the parts guy talk you into the AP985 if he doesn't have the APP985 in stock, it won't run well on the AP985. Really, nearly any good quality double-tipped platinum plug like Champion also sells is fine. Just make sure it is DOUBLE-tipped platinum where the platinum is on both sides of the gap.

Or you can run a conventional copper-core spark plug but those don't last more than about 1/3 as long as a good quality platinum plug will.

Edit: Those performance gains quoted by companies like who make the E3 and Splitfire plugs? Yes those are true but only when compared against an old worn out plug, which is how they can make those claims. Bu those claims are not true when compared against a good quality new plug like the Autolite APP985 which is what the newer distributorless 4.0L engines run well with. Or the single-tipped AP985 for older 4.0L engines that have a distributor.

I have a 99 TJ. Is it the newer or older 4.0?

(I know I could pop the hood, but it's damn cold outside).

[patricknolan]

Originally Posted by Jeep25

I have a 99 TJ. Is it the newer or older 4.0?

(I know I could pop the hood, but it's damn cold outside).

Its around 30 degrees! just stick your head under and look, should take all of about a minute. My thoughts on spark plugs: stick with the recommended by manufacturer and you will never go wrong.

I do work on my jeep all the time when its freezing cold!!

[Jerry Bransford]

Originally Posted by Jeep25

I have a 99 TJ. Is it the newer or older 4.0?

That's an older style with a distributor.

[Pillswoj]

Older, your 99 uses a distributer and the AP985 plugs will work well. The APP985's will also work but there is no benefit for the extra cost.

[tophusaf]

I just replaced my plugs in my 01 sahara, I bought champion and that is what came out of it as well. My concern is that after replacing the plugs and driving it for about a month my MPG has gone done by about 100 miles a tank. Any thoughts or suggestions on what could have happend?

[Jerry Bransford]

Was your battery disconnected at any point during your spark plug swap or afterwards?

[TheBoogieman]

Originally Posted by tophusaf

I just replaced my plugs in my 01 sahara, I bought champion and that is what came out of it as well. My concern is that after replacing the plugs and driving it for about a month my MPG has gone done by about 100 miles a tank. Any thoughts or suggestions on what could have happend?

WelcomeDid you check the gap on them?

[urstolendesire]

ok so I just pulled them out and to my suprise, there not oe. They are NGK R 7FR5N. looking it up on advnace auto, I see they at least sell them but these look pretty worn. Would these be a good replacement or would the app985 plugs be alot different?

[Pillswoj]

NGK was a OE supplier for Jeep, so they could be OE. For longest service life go with the APP985

[tophusaf]

Yes it was disconnected during the swap, and I did verify the gap was set at .35 which is what it said under the hood.