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Horrid gas mileage!

T

tnfan77

NAXJA Forum User
Location
Ft. Worth, TX
I have a 1990 Jeep cherokee limited with what I think is a rebuilt engine (4.0). On average, I get about 200 miles to a tank. This is just not going to cut it with how much gas is costing these days. Im just not sure what could be causing this. I think the o2 sensor is due for replacement, but from what ive read in the archives by searching, this will gain me about 3-4 mpg. I but right now im getting about 10 mpg. Also, all my driving is city, if that is a factor. Also, my tires are stock sized. Im just afraid of lifting my rig because the gas mileage is only going to go down. Thanks! :doh:

Jake
 
i get average 260 per tank with bone stock 2000. i go through a tank every five days at about 50.00 a tank down at the chevron.
edit: sorry. i honestly dont know how to get better mileage. for a four wheel drive vehicle 200 per tank sounds about good...other than going through everything that causes friction...?
 
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I have 31"s on my jeep and have been able to get 300 to the tank. I did the Bosch Platinum 4+ plugs, platinum wires and a conrad cap and rotor, That was myu biggest improvement. My plugs that were in it were absolutely shot and I probabaly went from at or just over 200 miles to the tank to 300 but that also includes my intake and exaust, But the biggest improvement was my ignition. My Jeep is as well a 90 with 160,000 miles on the original engine.
 
I am also right around the 300 to 330 mark. After I installed a new O2 sensor my gas mileage got better and I also thing that a good tune-up helped.
 
tnfan77 said:
I have a 1990 Jeep cherokee limited with what I think is a rebuilt engine (4.0). On average, I get about 200 miles to a tank. This is just not going to cut it with how much gas is costing these days. Im just not sure what could be causing this. I think the o2 sensor is due for replacement, but from what ive read in the archives by searching, this will gain me about 3-4 mpg. I but right now im getting about 10 mpg. Also, all my driving is city, if that is a factor. Also, my tires are stock sized. Im just afraid of lifting my rig because the gas mileage is only going to go down. Thanks! :doh:
Jake
Click to expand...

If your engine's running rich (I'll be surprised if it isn't), replacing the O2 sensor is a good place to start. A 3-4mpg improvement is definitely worth it. You could also replace other items like cap, rotor, plug wires, and plugs if they're also old.
If none of these measures work, hook up a vacuum gauge to the intake manifold and take readings at idle, 1500rpm, and 2500rpm. It should read at least 16"Hg. Let us know what you find.
 
I had the O2 sensor recall done on my 90 4.0 last week. My mileage immediately went from 10mpg to 17mpg... and it didn't cost me a dime!

Have new plugs, wires, and cap to install still, so will probably get a little bit out of that as well..
 
Wait, Tell me about your O2 sensor recall. Was it on all 90's. I have a 90 as well. Also, When I measured that 300 miles to the gallon. I towed twice, a total of about 25 miles, and 4-wheeled a little.
 
Call your dealer.
 
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