How to Improve MPG in a Jeep XJ

The Jeep Cherokee XJ was manufactured between 1984 and 2001 before being retired. The vehicle came stock with several different engine sizes, including the popular 4-liter six-cylinder engine. The XJ is typical of most sport-utility vehicles in that it is available in a four-wheel or two-wheel drive. The gas mileage for the XJ, as with most SUVs, leaves a bit to be desired. The mileage will range between 15 and 28 miles per gallon depending upon the engine size, vehicle type and age of the vehicle. Improving the gas mileage is simple.

Things You'll Need

• High-flow air filter
• Platinum or iridium spark plugs
• Screwdriver
• Socket wrench
• Spark plug socket
• Carburetor cleaner
• Engine oil additive
• High-mileage or synthetic engine oil

Instructions

1. Replace the existing air filter with a high-flow lifetime air filter, available from any auto parts store. Most air filters on the Cherokee are removed using a screwdriver to take off the retaining screws on the air filter housing. The new air filter slides into place just like stock air filters. Reinstall the air filter housing cap and secure the retaining screws.

2. Remove and replace each spark plug one at a time with a platinum or iridium spark plug. Double-headed platinum plugs are available that increase the frequency and efficiency of the spark going into the engine. This improves the gas mileage. Disconnect the spark plug wire from the plug, insert the spark plug socket attached to a socket wrench into the spark plug hole, and unscrew the old plug. Insert the new plug into the hole and tighten the plug down. Replace the plug wire and repeat the process for the next spark plug.

3. Clean out the fuel injectors. Take the vehicle to a professional shop for engines with electronic fuel injection for an injector cleaning. You can remove the air filter housing on carbureted engines and spray carburetor cleaner into the open ports on the carburetor with the vehicle running. Spray the carburetor in 10-second spurts while revving the engine. Continue until the engine sounds more stable when idling.

4. Take the vehicle to a lube shop for an oil change every 3,000 miles or more. Have the shop use a synthetic or high-mileage oil with an oil additive geared at maintaining and repairing engine seals.

5. Keep the tires aired up according to factory specifications. Most Jeep XJs call for 35 pounds per square inch (PPI) of tire pressure.

6. Take the vehicle to an auto repair shop to have the OBD system (On-Board Diagnostic) read for any error codes. Error codes will indicate that a vehicle sensor is malfunctioning, which can cause your gas mileage to increase. Have the shop replace any damaged sensors.

References

• Autozone: 2000 Jeep Cherokee
• JeepIN.com: Stuff: History