Which spark plugs

[jeepdude832]

I think I need a tune up. My milage is going down and I havent put bigger tires on it. I probably need a tune up cause I have 110,000 miles. On my blazer I had to put AC delco in. I am new to jeeps and I wasnt sure if there is a certian plug for 4.0 tj s thanks

 

[Tug-n-pull]

Ask 10 people and you will get at least that many answers. Bosh for me! Why? I do not have any idea! tug

 

[jay79cj7]

I took stock Champions out of my 4.0 and have replaced them with Champions both times I have changed them out. That is only because they are the cheapest at the store. Everything that I have heard is that it doesn't really matter too much.

 

[TwistedCU]

Lift springs w/o the kit

Bosch double platinums in mine - I'll try just about anything for a wee bit more zong out of the lil 2.5!!!

 

[far_right]

most plugs are pretty equal but i would run fast and run far from champions.... they foul pretty quick... also would use autolite

 

[chinard]

Considering that the 4.0 engine isnt exactly a high performance race engine, you should be looking for a brand that has a good reputation for reliability and longevity.

I use the bosch double platinums myself, but then again i've upgraded my igntion and re-gapped for a bigger spark.

Oh, when you take out the old plugs... examine them carefully and compare them with the discoloration chart in the back of your haynes manual. Make sure there are no other major problems that might be slowing you down.