Dan91

This is after new plugs, wires, cap, rotor just 2 weeks ago. It sat for a year, but has all new gas in it now. It idles and revs smoothly. I've got a couple exhaust leaks at the muffler. It is on 33s and I am taking that into account on the milage calculations. So, any ideas? For reference, 1.5 years ago it got around 12mpg. This is all city driving.

Thanks,
Dan

DieselD

Automatic? Stock gears? 33s?

If so, 10mpg, might be right.

And how exactly are you calculating mileage? If you don't have a corrected speedo gear, then do it by GPS. Otherwise it won't be right.

scheetz_21

its a jeep! lol if you got stock gears sounds right... im on 35s and get 10 all day! except now its all tore apart in the barn lol

Dan91

Auto, stock gears. I was averaging around 12mpg city a year and a half ago, that's my main concern. Anyways, I was calculating the ratio of my 33s against a stock size of 225/75/15. This gave about a 13% difference, so I multiplied the tripometer by 1.13. To be sure I did a test with my GPS today over about 15 miles. The results were spot on with my approximation. Anyways, given that my method is proven, I got 10.3mpg on my last tank. I tossed in a new air filter and a (less) used set of injectors since, and Ill calculate again for this tank.

1998xjspt

i to stock gears and auto tranny. I'm putting 31 on. will it effect my mpg a lot?

Slim357

I have 31s and stock 3.55 gears and lsd stock rear axle granted its an 89 with the Renix motor I get 12 mpg with moderately quick acceleration and if Im lucky when I drive like I have sense I get 19mpg once in a while in the city lol

The Rooster

If your jeep has over 100k I recommend doing both o2 sensors you will be surprised on your mileage per gallon increase ... This is one of the most overlook things for bad gas mileage

Dan91

Good idea, I'll test them soon.

The Rooster

A bad or lazy o2 sensor will not trigger a check engine light not sure how you can check them honestly...

Dan91

With a multimeter, when they get hot (test with jeep running at temp, or remove them and use a torch) they should put out about 1volt. They should also drop in voltage very quickly after removing heat. It's a pretty simple test and it gives a fairly good idea of the condition of an O2 sensor

Bluebyu

Not to bad. I just made the switch recently and it dropped 1 or 2 mpgs.. feels like a turd though haha much slower then the stock tires.. can't imagine how you guys run 33s and up on stock gears