Yes, another spark plug thread....so in my search for knowledge for the copper champion plugs being everyones general favorite plug, I came across something I can't figure out.

91-98 4.0's take an E412 champion and 99-01 4.0's take the E438 champion.

Anyone know why, and or what the difference between the plugs are and the years?

If it were 91-99 and 00-01 split I could understand as the 00-01 has the distributorless ignition.....but 99 does not.

I just found it to be strange and was curious if anyone knows why it's like that.

 

Some late 99 XJs went to coil on plug ignition, the WJs and TJs went to coil on plug in 99

 

the different numbers are in reference to heat ranges how cold or hot a spark plug fires

 

Why are Copper Plugs preferred for XJ's? Just curious cause i'm thinking of swapping out the Autolites I have in mine.

 

never heard that i run champions tried and true for 15 years

 

I run Champion Copper plugs in 84-99 4.0 engine

And NGK in the 00-01 with the coil pack distributorless ignition.