Poor fuel mileage

JESSIE473

MEMBER
2003 JEEP GRAND CHEROKEE
4.0L
6 CYL
2WD
AUTOMATIC
120,000 MILES

Still gets ten mpg, has not set any codes, runs and starts perfect. Just can't get over ten mpg. Could it have something to do with exhaust? It has a slight vibration at idle I can feel in the steering wheel only. Thanks for any advice you can give me.

Thursday, March 14th, 2019 AT 2:26 PM

3 Replies

ASEMASTER6371

MECHANIC
52,797 POSTS

Good afternoon,

Fuel mileage has a lot to do with driving habits. Short runs give you less miles.

Tires are a factor, alignment and the transmission working correctly are key factors as well.

Roy

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Thursday, March 14th, 2019 AT 2:31 PM

AHMAZEZING

MEMBER
1 POST

A slight vibration at idle could be a misfire that the computer isn't reading. Bad o2 sensors can also result in bad gas mileage. Usually a bad O2 Sensor will give a Check Engine Light.

The best option would be to have someone scan the computer for codes, or scan them yourself if you have the tool.

A standard tune up with spark plugs, wires, and rotor cap and button are a good place to start if you haven't done this recently.

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Thursday, March 14th, 2019 AT 2:50 PM

ASEMASTER6371

MECHANIC
52,797 POSTS

A bad O2 sensor would give you other symptoms.

There most likely is nothing in the computer. You would have check engine light if there were some readings that were off.

This is a basic issue as I discussed.

Roy

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Thursday, March 14th, 2019 AT 4:14 PM