Originally Posted by bustedknuckles
Ok great but as asked above, what specific model Champions? Some Champion spark plug models listed as appropriate for the TJ won't work well on 2000 and newer that have the distributorless ignition system. For example, the Champion 3034 is listed as ok but its single-tipped platinum coating design (platinum on just the center electrode) can cause rough idles, missing, etc. If the 3034 is installed, replace it with the 7034 which is double-tipped platinum... i.e. its platinum coating is on both sides of the gap. This is important because the TJ's distributorless ignition fires each plug on every stroke but in opposite directions every stroke.