fuel economy tricks.
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Member
Joined: Jan 2011
Posts: 224
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From: Henderson, NV
Year: 2000
Model: Cherokee
Engine: 4.0
I have a 2000 classic with the 4.0 and auto. Its lifted 4" on 31s. Im getting about 12mpg city and 14 hiway. Any tricks for bringing that up? One of the guys i work with has a stock 96 with 5 speed. He claims 23 hiway. I know i lose with the auto and big tires but should i really lose 10mpg with this setup?
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 24
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
I'm no expert here but I maybe learned something last week. In a nut shell if the computer thinks the engine is cold it will enriches the mixture causing bad mileage. Warmed up it uses the O2 sensor to adjust the mix for optimum. Your 2000 may have a code thingy. Might even be a way to turn your key on and off and somehow and make a light blink in code on your dash. My stock 90 is only getting 16, (with 260+K), But I think its (Renix ?) might be in (open loop?).....maybe a temp sensor thing....There's a start. Let me know when you figure the rest out! Don
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Joined: Aug 2011
Posts: 43,971
Likes: 1,579
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
I'm no expert here but I maybe learned something last week. In a nut shell if the computer thinks the engine is cold it will enriches the mixture causing bad mileage. Warmed up it uses the O2 sensor to adjust the mix for optimum. Your 2000 may have a code thingy. Might even be a way to turn your key on and off and somehow and make a light blink in code on your dash. My stock 90 is only getting 16, (with 260+K), But I think its (Renix ?) might be in (open loop?).....maybe a temp sensor thing....There's a start. Let me know when you figure the rest out! Don
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,579
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
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CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 24
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
I don't bite bullets. Scottish tight ***. Missing a briquette? I'm making a diamond as we speak! Yea...well my DBRBR..whatever is in the shop, voltmeter eh?
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,579
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Yeah. EcoMike on NAXJA did a little write-up on testing the Renix O2 sensors. Your a$$ wouldn't be so tight if you weren't wearing a kilt!!!!
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 24
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
EE---OW___I*** think A ohhhh Kilt might help this
EcoMike on NAXJA Guess I'll try a search....Was a nubee the other day.
That's funny! Wanna guess where the search got me? BACK HERE!
Found it, (for 87 to 90 Renix)
http://www.naxja.org/forum/showthrea...ht=sensor+test
I'm gone, didn't mean to hijack your thread, D.

EcoMike on NAXJA Guess I'll try a search....Was a nubee the other day.
That's funny! Wanna guess where the search got me? BACK HERE!

Found it, (for 87 to 90 Renix)
http://www.naxja.org/forum/showthrea...ht=sensor+test
I'm gone, didn't mean to hijack your thread, D.
Last edited by DFlintstone; Aug 27, 2011 at 12:52 AM.
Senior Member
Joined: Apr 2011
Posts: 746
Likes: 3
From: here today gone tomorrow
Year: 1996
Model: Cherokee
Engine: 4.0
Maybe not. My mostly stock '96 Sport with auto gets 21-22 on extended runs on the highway. We bought it new and it has always gotten better mileage running 89 octane vs 87. Higher than 89 didn't improve mileage.
Last edited by excess650; Aug 27, 2011 at 06:41 AM.
CF Veteran
Joined: Jun 2011
Posts: 2,858
Likes: 1
From: Nor-Cal
Year: 1990
Model: Cherokee
Engine: The venerable 4.0
@flinstone for some reason people tend to report a little better mileage with renix. On that note when I drove mine home on 33s it had open vacuum lines and some messed up wiring. I did however get 20+ on the hwy at 60mph the whole way. Since I have fixed everything its down to about 17-18 :-( city is crap though like 13-14
CF Veteran
Joined: Jun 2011
Posts: 2,858
Likes: 1
From: Nor-Cal
Year: 1990
Model: Cherokee
Engine: The venerable 4.0
Originally Posted by DFlintstone
"crap though like 13-14" is like what I get up north treating it like a tractor, yarden trees and dragging meat back to my cave.



on your fuel bill.