Is there anything at all I can do to improve my gas mileage enough that it will be noticeable? It's a 98 tj 4banger with 33s and 4" suspension lift. At around 12-13 mpg but I feel like someway it could be better. I get around 140-150 to a tank now and it only takes about $30-$35 to fill up. What can I do?
It's a Jeep. Fuel economy isn't the best for them. 12-13 MPG isn't great but you can do a few things to improve the gas mileage.
When you went to bigger tires did you change the spedo gear in the transfer case to match your gear ratio and tire size? This will bring your mileage back to pretty damn close to factory specs.
Being that you have a 4 banger like mine with the 4.11 gear ratio, changing to the right speedo gear made a huge improvement in fuel economy. I went from 13 combined to 15/16 combined and it there are no hills involved I sometimes can get it up to 17/18 but rarely. 1/2 tank fill up around 25.00 as of yesterday @3.55/gallon.
Change your injectors to the Ford Bosch EV-1 type III injectors out of a 7.5 big block or a Mustang 5.0. This will give you more power and slightly better fuel economy but nothing to right home about. These are the numbers for the injetors.
Bosch reman number 0280150947
Ford part number FiTE-D58
Blue top EV-1 Series III
you can find them on Ebay as I got mine for 27.00 per injetor with 8.00 shipping.
Put the Throttle Body out of a Jeep with the 4.0 engine. Do this and change over all from your 2.5 TB to the 4.0 TB or it will peg the tach as the computer will read it wrong.
Air induction and exhaust. Get a high flow exhaust and a cold air induction as this will help some what with the power end.
Cooling Fan, There is a question weather to go electric or go flex-a-lite fan. to me either one will work as the flex-a-lite will flex sending more air the faster the engine revs but the electric fan restores some power to the engine as it doesn't have to work as hard.
Then there is every ones favorite. Re-gearing to 4.88. as this will give you more power and make your Jeep roll faster. This isn't cheap either.
The thing about fuel economy is this, there is always a trade off and having been in the engineer field working with fuels for over 20 years, there isn't much you can do to increase fuel economy. People think that chips and the what not can do this but there is no chip to improve fuel economy for a 4 banger and it's a waste of money. Gain power in the 4 banger. The more power you have the less likely you will step on that little skinny pedal.
In my opinion the transmissions for the 4 bangers were geared wrong especially the 5 speed as it should have been geared lower so that 5th gear should have really been the 4th gear or just eliminate the 5th gear altogether. Hills are a ***** 3rd gear at 3 grand on the tach not a way to drive a stick. I have no experience with the auto in a 4 banger so someone will have to help you on that one.
Hope this helps somewhat.
