NAXJA Forums -::- North American XJ Association  

Go Back   NAXJA Forums -::- North American XJ Association > NAXJA Unibody Jeep Technical Forums > Jeep Cherokee XJ (1984 - 2001) > OEM Tech Discussion
HOME Member FAQ Sponsor Info Rules Bylaws E-Mail

OEM Tech Discussion Forum for OEM (Original Equipment) or stock XJs and MJs.

Reply
 
Thread Tools Display Modes
  #46  
Old October 15th, 2019, 17:24
paulhead's Avatar
paulhead paulhead is offline
I overtighten $#!t
 
Join Date: Dec 2004
Location: where compton meets the water
Posts: 1,668
Re: Bad gas mileage 10-11 MPG

Quote:
Originally Posted by kastein View Post
Your temp gauge on a 96 and earlier uses a separate sender from the ECU, so that doesn't really rule anything out, unfortunately.

87-90 4.0: 3 temp sensors
- 1 in the left radiator end cap to turn the electric fan on (HD cooling option only)
- 1 in left side of block low down for the ECU
- 1 in the back left side of the head on the top for the gauge

91-96 4.0: 2 temp sensors
- 1 in the thermostat housing for the ECU, which now also controls the fan
- 1 in the back left side of the head on the top for the gauge

97+ 4.0: 1 temp sensor. It's in the thermostat housing and the ECU controls the fan as well as sending the data to the instrument cluster

Honestly it sounds like you've gone through most stuff. If there is even a small crack in the exhaust manifold - very common at the 2 to 1 collector - it will suck in air in between exhaust pulses and this will cause the O2 sensor to read leaner than it should no matter how much fuel the ECU dumps in to compensate, because that air doesn't ever meet the extra fuel in any meaningful way until they both end up in the catalytic converter. I've seen an XJ get single digit fuel economy due to this problem and jump to 15-16 after it was fixed.
cool thank you, will check it out
__________________
“Lead me, follow me, or get out of my way. ”
-Gen. George S. Patton Jr.
Back at step 1, bought a YJ, an XJ going under the knife....
Reply With Quote
  #47  
Old October 16th, 2019, 00:50
ijeeep ijeeep is offline
NAXJA Forum User
 
Join Date: Oct 2019
Location: Pacific Northwest.
Posts: 8
Re: Bad gas mileage 10-11 MPG

Other things that eat milage: less than perfect ground connections, the sensors need excellent ground connections all the way back to the ECU or else the signals are weak and the ECU responds by richening the mixture. ( poor grounds are why the headlights get dim as XJs age ). Dragging fan clutch will eat a few mpg too.
Reply With Quote
  #48  
Old October 16th, 2019, 08:14
denverd1's Avatar
denverd1 denverd1 is offline
NAXJA Member
 
Join Date: Dec 2013
Location: Tyler, TX
Posts: 720
Re: Bad gas mileage 10-11 MPG

Quote:
Originally Posted by blu3fan View Post
I hate to tell you this.
but with the 35's and the lift. 10 mpg sounds right.
my stroker gets 8-12 city almost 20 highway. Im running 32's
Agree, I don't think it's that far off

Although new plugs HAVE to help

Sent from my SM-G975U using Tapatalk
__________________
Chili Pepper '98
4.5" lift, locked on both ends, 33s
10K winch and a lot of skinny pedal
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Why is my gas mileage so bad walkerja191 Modified Tech Discussion 33 January 6th, 2009 21:52
gas mileage mitsumotors Modified Tech Discussion 61 December 27th, 2007 20:33
Better mileage icebergmedic Modified Tech Discussion 6 November 21st, 2007 13:23
Where the gas mileage go? balor OEM Tech Discussion 5 November 2nd, 2005 17:07
No cat mileage ParkCityXJ Modified Tech Discussion 8 December 29th, 2004 00:10


All times are GMT -7. The time now is 06:40.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
NAXJA and NAXJA logo's Copyright NAXJA. All content/images Copyright NAXJA 1999-2014