The 5.9 in the Jeep is (was, it has about 7k miles now) a fresh rebuild. New tune parts with MSD wires and coil, O2 sensors, distributor, CPS, TPS, cat, and MAP. It's frustrating.

I'm planning on getting some center dump headers for it, opening the exhaust up to 3 in after the a-pipe, and an SCT programmer. For 10mpg, I want it to be a monster.

 

Not sure, but with 160k on it I plan in rebuilding the diffs soon anyway. Probably drop in 4.10s or 4.56s.

What is stock? 3.55 and 3.73?

 

Actually with the 5 speed 3.55s aren't bad, the OD ratio is higher than the auto so it helps on the highway, with 31s I turn 2200RPM at 70 which is just about perfect, if you don't mind higher RPMs or like going slower (Your Oregon speed limits are slow anyways ) then 3.92s would work well.

What tires and gears in the TJ? 10MPG is pretty awful.

 

4.88s and 35s. I spin a little high, but don't even drive the freeway much.

 

Yeah that's a pretty good combo. Did you replace the plenum gasket when you did the rebuild?

If it makes you feel any better I've only been getting about 12MPG when I take my B2 up in the mountains lately with a 4.0, but I drive the **** out of it.

 

I did, but used the stock plate. Didn't get the Hughes plate. Maybe it's failed? I looked down the TB and there's a bit of oil residue up on the sides if the intake. I'm guessing there is some sort of leak, since there is no other way for oil to get in there. Well, except up the intake valves, but I had a valves job when I built it.

edit: and I get more like 7 or 8 when I'm wheeling. But I have a heavy right foot.

http://smg.photobucket.com/albums/v2...0-23-10230.mp4