Better Fuel Economy?

[notabrick]

Hey I have a 99 grand cherokee and i love it but hate crappy gas mileage. Do you know of any tweaks or aftermarket products that could help improve that, even if i have to trade in some power to get it?

[JDPascal]

Welcome to AF notabrick!!

What kind of crappy gas mileage do you think you are getting??

how many miles on the jeep?

how many miles since a tuneup?

Have you had it emissions tested recently?

What engine??

Which 4wd system??

Do you have the mileage computer in the overhead console??

If you do have the computer, fill up with fuel and take it on a 40 to 50 mile trip with no stops. Reset the computer while you are driving down the road at highway speeds. Set the display to "avg mpg" and watch the results while you drive a steady 60 mph or eqivalent engine rpm. It will likely start out high and come down to stabilize at the actual average. When I reset before I start moving or at city speeds, it seems to take longer to get to the actual average but maybe I just don't like looking at the low numbers for so long.

When I do that on my 96 JGC with a 5.2, it starts out at 21 - 22 and alway seems to settle out at about 19.2 m/usg after about 40 miles at around 1900 engine rpm on cruise.That seems to be where I get the best mileage on the highway.

City mileage though, depends more on the drivers driving habits.

Have a look and get a base MPG at a set highway driving condition like this, then you have something to compare to when you make changes or do a tuneup then let us know what you have found.

JD

[g1smith]

I think we are all looking for a magical answer such as adding acetone to our gas to gain 10% to 30% more milage or perhaps a turbo-charger, performace chip, after-market ignition system, K&N air filter etc. etc..

Possibilities:
1) Aerodynamics - I've read a college study re pickup beds. The study basically determined that it is best to leave the tail gate up than down, better to install a bed topper, and best to install some kind of special tear-drop shaped bed topper. I was surprised to learn what kind of mpg improvements can be gained with a top. As far as the JGC, what can realistically be added to reduce drag created at highway speeds?

2) Disconnect the front drive shaft

3) Maintain tire pressure and don't install oversized, aggressive off road mud tires.

4) Maintainance. Tune-up eg spark plugs, wires,

Any other ideas?

[natu'sii]

Try changing the spark plugs to "bosch platinum +4", change the air filter to a K & N filter (NOT a disposable type). I get 25 to 30 mpg when cruising down the highway depending on speed. Starting around 60 I get 28, then if I go 70 I get 25. Which is pretty good for a 5.2l V8. My tire size have changed to 235 70R/16 this is on a 1997 Jeep GCL with 225000 km.

[hulkmn069]

Originally Posted by g1smith

I think we are all looking for a magical answer such as adding acetone to our gas to gain 10% to 30% more milage or perhaps a turbo-charger, performace chip, after-market ignition system, K&N air filter etc. etc..

Possibilities:
1) Aerodynamics - I've read a college study re pickup beds. The study basically determined that it is best to leave the tail gate up than down, better to install a bed topper, and best to install some kind of special tear-drop shaped bed topper. I was surprised to learn what kind of mpg improvements can be gained with a top. As far as the JGC, what can realistically be added to reduce drag created at highway speeds?

2) Disconnect the front drive shaft

3) Maintain tire pressure and don't install oversized, aggressive off road mud tires.

4) Maintainance. Tune-up eg spark plugs, wires,

Any other ideas?

the acetone does work but it's bad for the valves. makes gas too dry and takes away from the lubricating properties. but, cold air kit tb spacer, bored tb good plugs and regular tune ups with highway tires will help out. ps tb throttle body. also synthetic blend motor oil and regular trans flushes will also take some off as well as changing the diff fluid regularly or even to synthetic