10 mpg on 99 xj
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CF Veteran
Joined: Sep 2009
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From: Williston, North Dakota
Year: 1999
Model: Cherokee
Engine: 4.0L
This is after new plugs, wires, cap, rotor just 2 weeks ago. It sat for a year, but has all new gas in it now. It idles and revs smoothly. I've got a couple exhaust leaks at the muffler. It is on 33s and I am taking that into account on the milage calculations. So, any ideas? For reference, 1.5 years ago it got around 12mpg. This is all city driving.
Thanks,
Dan
Thanks,
Dan
CF Veteran
Joined: Apr 2011
Posts: 4,825
Likes: 2
From: Indianapolis
Year: '99 and '91
Model: Cherokee
Automatic? Stock gears? 33s?
If so, 10mpg, might be right.
And how exactly are you calculating mileage? If you don't have a corrected speedo gear, then do it by GPS. Otherwise it won't be right.
If so, 10mpg, might be right.
And how exactly are you calculating mileage? If you don't have a corrected speedo gear, then do it by GPS. Otherwise it won't be right.
Thread Starter
CF Veteran
Joined: Sep 2009
Posts: 1,295
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From: Williston, North Dakota
Year: 1999
Model: Cherokee
Engine: 4.0L
Auto, stock gears. I was averaging around 12mpg city a year and a half ago, that's my main concern. Anyways, I was calculating the ratio of my 33s against a stock size of 225/75/15. This gave about a 13% difference, so I multiplied the tripometer by 1.13. To be sure I did a test with my GPS today over about 15 miles. The results were spot on with my approximation. Anyways, given that my method is proven, I got 10.3mpg on my last tank. I tossed in a new air filter and a (less) used set of injectors since, and Ill calculate again for this tank.
CF Veteran
Joined: May 2012
Posts: 3,004
Likes: 1
From: Wilmington,NC
Year: 1989
Model: Cherokee
Engine: 4.0
I get 19mpg once in a while in the city lol
CF Veteran
Joined: Feb 2011
Posts: 3,074
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From: Bergen County, New Jersey U.S.A.
Year: 1990 Laredo
Model: Cherokee
Engine: 4.0 Inline 6 Renix
If your jeep has over 100k I recommend doing both o2 sensors you will be surprised on your mileage per gallon increase ... This is one of the most overlook things for bad gas mileage
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Thread Starter
CF Veteran
Joined: Sep 2009
Posts: 1,295
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From: Williston, North Dakota
Year: 1999
Model: Cherokee
Engine: 4.0L
Thread Starter
CF Veteran
Joined: Sep 2009
Posts: 1,295
Likes: 0
From: Williston, North Dakota
Year: 1999
Model: Cherokee
Engine: 4.0L
With a multimeter, when they get hot (test with jeep running at temp, or remove them and use a torch) they should put out about 1volt. They should also drop in voltage very quickly after removing heat. It's a pretty simple test and it gives a fairly good idea of the condition of an O2 sensor
Seasoned Member
Joined: Sep 2012
Posts: 446
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From: Long Island, NY
Year: 1998
Model: Cherokee
Not to bad. I just made the switch recently and it dropped 1 or 2 mpgs.. feels like a turd though haha much slower then the stock tires.. can't imagine how you guys run 33s and up on stock gears
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