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1994 Jeep Cherokee - Can I get better MPG?

Want find out how to get more gas mileage in my Jeep Cherokee? What can I do to fix the problem myself? Thank you.

Fuel efficiently and Jeep Cherokee don’t belong in the same sentence. Use your search engine for ( Hypermiling ) and you might get some tips there . Other then that your driving habits are the only thing you can really change.

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Low rolling resistance tires would help too, although I don’t know if there are many of those options for Jeep tires. Tirerack.com would help @katdog with that search

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Besides agreeing with the previous posts (driving habits/style + possibly finding low rolling-resistance tires), I want to add that good maintenance can also help… to a small extent.

The EPA rating for your vehicle is 17 mpg city/20 mpg highway if it is 4WD.
If it is RWD, it is rated at 18 mpg city/22 mpg highway.

If you drive “conservatively” and maintain it properly, you may be able to match those numbers.
If you can find low rolling-resistance tires, you might be able to add 1 mpg to those figures.
However, getting a drastic improvement in gas mileage is simply not possible.

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Maintenance up to date, including changing fluids as recommended, including the axles and transaxle? Tires fully inflated to the correct pressure, measured before any driving that day? Driving conservatively? That’s about it.

What mpg do you get?

How long have you owned it?

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I’ve owned 3 rear wheel drive Cherokees from the early 90s and those EPA mileage figures are in line with what I experienced. One 4 wheel drive that owned was at or above the rear wheel drive mileage and 2 others were somewhat below EPA. I owned a few others, all 4 wheel drive but never took extended trips in any of them, they were bought to repair and flip.

If there is nothing wrong with it and you did find a way to help the fuel economy it would not be by much. Keep your tires inflated to specs and then some and at least you won’t be cheating yourself. Have the alignment checked to see if it’s way off.

A marginally failing MAP sensor or engine coolant sensor could reduce mileage without setting a code. But it might require someone very familiar with normal(?) ranges on a live data stream.

What kind of fuel economy are you currently getting?
How did you arrive at that figure?
How long have you been keeping track of your fuel economy?
Has there been a drastic change in fuel economy lately?

If you have a 4WD 4.0L Cherokee, then realistically, you can expect around 16-19 MPG overall. If that’s what you’re getting then, there’s probably nothing wrong with your vehicle, and there’s no “problem” to fix.

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Better mileage is certainly possible, but better than what? the easiest way to improve your mileage is dump the Cherokee and get something like a Camry.

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In stop-and-go driving, your driving habits (accelerating, anticipating, braking, etc.) predominate. Removing any excess weight in the car can also help a little.

In highway driving, your speed and the rolling resistance of the tires become bigger factors, but also wind resistance: any roof rack will hurt MPG, and it can be a very big factor with, say, bicycles up there. Taking off the crossbars can help reduce wind resistance and wind noise.

The crossbars on my Town and Country minivan can be moved fore and aft. There are little triangles at 2 positions on the sidebars - I assume those are recommended placements of the crossbars, for less noise and better MPG.

Would be helpful to know what mileage you’re now getting.

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A couple other questions I didnt see asked. Is it lifted, bigger tires, performance chips or otherwise mods?

If it’s even slightly lifted above stock or running larger than stock tires then the gas milages above will be a good way off. Alignment proper tire inflation, amount of miles on drive train brakes adjusted and not dragging, type/weight of oil and driving style all effect mpg, bad or sluggish o2 sensors are a huge issue, block or ecm temp sensor can have huge effects as well, clogged cat converter also.

I would start by pulling live data from the ecm while running and compare to specs…temps timing calculated load throttle position and percentage short and long term fuel trims…all these can give you a “base” picture of how well the engine is performing, if everything is close to spec, then look at the stranger things like a rear brake shoe dragging or front caliper not releasing fully

It would help to know your current mpg vs what’s published…if it’s a huge difference then almost all the above all the way down to a simple vacuum leak can cause 2 or 3 mpg loss

Have you heard of Technical Bulletin 09-05-00?
Assuming you have a V6 or V8 engine.

SUBJECT: Spark Knock And Engine Oil Consumption Due To Intake Manifold Pan Gasket Oil Leak
OVERVIEW:
This bulletin involves the replacement of the engine intake manifold plenum pan gasket.

The plenum gasket leaks and manifold vacuum allows oil to get sucked from the engine galley into the fuel intake stream and lower fuel octane; a pinging sound under acceleration is an indication.

I had a 1995 Grand Cherokee 5.2L and this was the problem. The JEEP got 13 MPG around town and 17 to 18 MPG on the highway after replacing the gasket. Fixed the problem at about 125,000 miles and sold it at 175,000 miles on it. Engine was still running strong and did not burn any oil after replacing the plenum gasket (cost was around $1,000 to repair).
If you can find the bulletin, it describes a simple vacuum test to diagnose and confirm a leaking plenum gasket. If you do replace the gasket, be sure to purchase the metal gasket from JEEP.
I had a difficult time figuring out what the problem was and the only indication was lower mileage and pinging under load. Finally, I found the Technical Bulletin.

I have replaced those intake manifold belly pan gaskets however the Cherokee does not come with either of those Magnum engines. The Cherokee came with a 4 cylinder or inline 4.0 liter Jeep engine.

I believe I was paid 3 hours of labor for those repairs, comes to about $500 for parts and labor.

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OP was five days ago with no responses to questions. I think he/she is done.

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