ok, here's a mileage question.

I have a roofrack with lights and a spare 33x10.5 tire on it, and I'm lifted 5" on 33x10.5s. My gears are 4.10s, and my mileage is around 5-8 MPG city, and 7-12 highway. Does this sound right, or should I look into bad O2 sensors and such? I'm pretty sure the speedo gear is correct, I originally got this from my brother already lifted and on 33s so I'm not sure. I know that the speedometer isn't wildly incorrect.

Check speed-o gear, then check mpg.. Then if it is that bad, i would do a tune up an change my o2

XJ98Jeep said:

I have a roofrack with lights and a spare 33x10.5 tire on it, and I'm lifted 5" on 33x10.5s. My gears are 4.10s, and my mileage is around 5-8 MPG city, and 7-12 highway. Does this sound right, or should I look into bad O2 sensors and such? I'm pretty sure the speedo gear is correct, I originally got this from my brother already lifted and on 33s so I'm not sure. I know that the speedometer isn't wildly incorrect.

Click to expand...

Seems low. I only lose about 1 mpg with my Conn Ferr rack. With lights, I'm thinking you'd lose more.

The status of your O2 sensors should relate to your overall mileage, and I belive they should be changed at around 80k miles (?). How many miles on your heap?

You may also need to consider your driving style. If you are an old fart like me, you have no real desire to drive faster than 60 mph. Plus, I take off nice and easy to avoid spilling my cocktail.

Well here's what I got...

1991 with 375,xxx miles.
4.5" lift on 33" BFG ATs
Spare is on a carrier on the back.
Con-Ferr rack.
3.55s still

I get around 12 to 14 city and up to 18 or so on the highway. Yours sounds pretty low to me. I had my spare on my roof rack and noticed an increase of about 1 MPG after taking the spare off and could feel a difference in the way it drove. I have been told by friends that the rack itself tends to affect your MPG by around 2 MPG. Lights I would think wouldn't have that much effect since you have a big rack up there anyways. I still have 3.55s, but I expect my MPG to improve a little when I get my 4.56s installed. You should check your speedo gear and make sure you have the right one. With 4.10s and 33s you should run 36 tooth gear. I would go up to a 37 since your 33" tires aren't quite 33" and as you wear them they will get closer to 32". As long as you have a 36 or 37 tooth gear, though, you should be pretty accurate

Plus, I drive like an old fart like the guy above. I don't accelerate fast. I coast to red lights. I don't tend to go over 65.

X2 on O2 sensor if its over 80,000 and it hasnt been replaced its probably a good time regardless.

Which O2 sensor? All of them or a specific one? I know there are a few, I just can't seem to remember their positioning right now.

Pre cat i think

Def. the one before the cat. The one after just monitors how well the cat is working.

Sounds good, thanks guys. This thread will be long dead before I get the O2 sensor installed so if the O2 sensor doesn't work I'll just start a new thread.