High Rpm's, low gas mileage
Seasoned Member
Joined: Jun 2010
Posts: 448
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From: Charleston, SC
Year: 1990 - 2000
Model: Cherokee
Engine: 4.0
Sounds about right. My 5 speed with the same gears and tires runs about 22-25 MPH at 750 RPM (idle) thanks to my injector swap. So it would be 1500PRM at 45MPH.
CF Veteran
Joined: Mar 2010
Posts: 47,923
Likes: 38
From: Broward County Fl.
Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
Senior Member

Joined: Nov 2008
Posts: 972
Likes: 12
From: south bend indiana
Year: 1993
Model: Cherokee(XJ)
Engine: 4.0 i six H.O.
when u put the tps on,did it adjust its self, when you started it back up? did you make sure you iac is working? did you disconnect the battery before then connect after?
Thread Starter
CF Veteran
Joined: Mar 2011
Posts: 1,751
Likes: 3
From: Tampa Fl
Year: 1997
Model: Cherokee
Engine: 4.0 HO
i believe that on the 97+ they adjust themselves. its idleing perfect now. how do i tell if the iac is working? and no i dident disconnect the battery
Senior Member

Joined: Nov 2008
Posts: 972
Likes: 12
From: south bend indiana
Year: 1993
Model: Cherokee(XJ)
Engine: 4.0 i six H.O.
right the tps adjusts it self from 91 and up, when u line the grooves up with the tb and put the screws back in,and when you start it it'll rev at like 3000 rpms and then the rpms will start coming down in like a minute or so to where it should be. if it didnt do that then the tps isnt hooked up right. the iac, when you take it off, leave the electrical connector on and the pintel should be inward or outward ,then turn the key on(no start)and look at it again to see if it moved in or out. i cant remember if its supposed to be in or out at first. if it doesnt move its bad.
CF Veteran

Joined: Oct 2010
Posts: 2,150
Likes: 12
From: Ontario, Canada
Year: 1989 Laredo
Model: Cherokee
Engine: 4.0 L 6 Renix
60 mph at 2000 rpm sounds about right. My 506000km XJ on 31" on 15s turning 3:55 gear and standing up in the wind 3.5" gets 17.5 us mpg. My daughter's 265000km ZJ running her summer street 225-75 x 15, a 3:55 gear at stock height just pulled more than 440 miles out of a tankful of $4.54 usg liquid gold at 21.5 us mpg. Runnin the same roads and conditions. Keep the ignition parts, oil and filters fresh. On my older system that 1400 rpm idle would be suspect of fouling in the idle air control motor on the throttle body.
Thread Starter
CF Veteran
Joined: Mar 2011
Posts: 1,751
Likes: 3
From: Tampa Fl
Year: 1997
Model: Cherokee
Engine: 4.0 HO
right the tps adjusts it self from 91 and up, when u line the grooves up with the tb and put the screws back in,and when you start it it'll rev at like 3000 rpms and then the rpms will start coming down in like a minute or so to where it should be. if it didnt do that then the tps isnt hooked up right. the iac, when you take it off, leave the electrical connector on and the pintel should be inward or outward ,then turn the key on(no start)and look at it again to see if it moved in or out. i cant remember if its supposed to be in or out at first. if it doesnt move its bad.
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