Hey guys. I glanced around a little and didn't see any threads about this. I changed my spark plugs in my 06 rubicon. Since then, I'm getting a little worse of gas mileage and unless it's my imagination, a rough idle every now and then. I am getting about 12-13 mpg with highway/street combined, and was getting about 13-14. I have a 4" lift with 31s as well. Is this normal for everyone else?
Did you put in different brand plugs? Do a search--there are a variety of opinions on plugs. Factory were probably NGK for that year. Some people stick with those, some use Champion, some Autolite, etc. You may find that for YOUR Jeep one type might perform better. I put Champion in my 2004 and mileage is good (18-20) for my stock Jeep but it has a bit of a rough idle until it warms up.
"How the hell did you get all this together?"
"Just happened, Max, you know--a piece from here and a piece from there."
I have a hardtop LJ with a heavy 8274 winch and plate up front. 3.73 gears, 4spd AT, 31" KM2's. New plugs, new filters, new oil, new o2 sensors, new fluids everywhere. I get 12-13 mpg everywhere I go. I have timed miles to determine that I'm 3.5% off on my speedo which would add almost .5 mpg, which I find negligible. I am heavy(ish) footed and I see mostly freeway at the moment.
I only saw 14-15 with all new everything on my '99 soft top, so I've determined that these folks that claim 18-20 mpg are either calculating wrong, or are driving in a manner that would make me rather ride the bus.
For some, it is easier to kill the light inside of themselves than it is to fight the darkness all around them.
I get like 12 to 13 with 3.73 gears and 33s with a 4 inch lift. Does and intake and exhaust help? I am thinking of a tuner to even though in Cali they are not technically legal. Love my Jeep, hate the mileage.