Replacing spark plugs 04 TJ 4.0

futureeuqb

futureeuqb

Well-Known Member
Joined
Mar 22, 2008
Location
Burlington
What is the recommend spark plug when replacing the plugs in a 2004 TJ 4.0 6Cyl?
 
Stick with the OEM. I tried some kind of high-dollar platinum plugs in our 02 WJ with the 4.0 and we were nearly stranded. Garage told me the 4.0s don't like platinum plugs. OEM ever since and never another problem like that.
 
i just put whatever was medium priced from the autoparts store and they worked fine.
 
best thing to do on all 1996 and up rides is oem factory style plugs. and stick with the same brand.

lots of problems with idel / skip when running / surging .

also check the factory emmisions sticker under the hood . thay sometimes give the part no. of the plugs.
 
VortecJeep said:
Stick with the OEM. I tried some kind of high-dollar platinum plugs in our 02 WJ with the 4.0 and we were nearly stranded. Garage told me the 4.0s don't like platinum plugs. OEM ever since and never another problem like that.
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The later model 4.0s with the coil pack do not like regular platinum plugs. A double platinum plug like the Autolite APP985 or Champion 7034 is what is generally recommended for the distributorless ignitions. I run the APP985 and have been really happy with them
 
I will say that I run the APP985 plugs in my 2004 TJ. I had some light spark knock pulling up hills going about 45-50mph. I tried several plug sets over a few months, autolite standard 985 and a bosch plug. They both gave spark knock.

I could not find the champion truck plugs in my area so I went with the APP985 plugs and haven't looked back.
 
I went with the E3 spark plugs. Put them in about a week ago. Happy with them so far.
 
Oh, and I read they don't make the champion truck plugs anymore otherwise I would have probably gone with those.
 
Words of wisdom I got years ago:

"Buy the cheapest plug they got. Change'em when they wear out. The cheapest autolites are fine. Go with a champion if the engine is high mileage and uses a little oil, the champions run a little hotter and will be less prone to fouling."

I've followed this advice for 22 years with no problems.

That being said, a lot has changed over the years. I would go with whatever is OEM, as some have already mentioned. But I still don't believe in spending big money on spark plugs. 1.99 autolite versus $8 splitfire? Easy decision.
 
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