Question about 1989 Jeep Cherokee

2 Answers

My 1989 cherokee pioneer 4.0 has bad fuel economy ,i have been trying to increase fuel economy by getting new o2 senser ,new catalatic converter,new cap,rotor and wires, new map senser.i think i did i

Jeep Cherokee pioneer 4.0,2wd gas guzzler help

Posted by on

    TOM LEVINE Sep 08, 2015

    yes my milage is of today 9/8/15 271,000 miles. I did post this question sometime ago .I think I may pull another winter out of it.gas milage is still 11 to 13 miles nd I amtrying to gain more milage from what I had.thank ou for our time and answers



2 Answers

  • Level 1:

    An expert who has achieved level 1.


    An expert who has answered 20 questions.


    An expert that has over 10 points.


    An expert whose answer got voted for 2 times.

  • Contributor
  • 38 Answers

Wow-you own a workhorse of a vehicle that is going on its 25th year - good for you! Due to its toughness and reliability, the Cherokee was selected in 2011 as one of "10 cars that refuse to die" by Kiplinger. :-) The vehicle was never a gas sipper - research shows fuel economy for the 1989 model year averages 16-19 mpg combined (city/highway) dependent on 2WD/4WD/manual or automatic transmission.
I see you put some money into repairs, but you don't mention if your average mpg had suddenly decreased or you're simply trying to improve on the mileage you've always had. A catalytic converter change won't usually improve fuel mileage, but would likely improve your emissions which is a good thing.
The single best thing you can do is make sure your tires are properly inflated. Low tires create drag, increase rolling resistance and decrease mileage. Making sure your vehicle is tuned (caps, plugs, wires) to specs, changing your fluid and filters as required, all will keep your fuel efficiency as best as it can be.
You don't mention the mileage on your Cherokee, but a high mileage engine may benefit from a simple compression test just to make sure your cylinders are sound and worn rings are not robbing you of power.
Lastly, check to see what you are carrying in your vehicle. My dad would carry hundreds of pounds of tools and construction material in his vehicle - and then complain about the mileage! Keep the truck and insides with only what you need to keep it lighter.
Hope this helps!

Posted on Apr 01, 2014

Testimonial: "yes that sounds reasonable .ok here it is I bought the jeep about 2 years ago there testimonial is they drove the hell out of running into original owner not the guy I bought from but who he bought from says the motor was switched out as well as the trans that has the tow package with dash switch that changes ratio in trans .anyway this diinasaur has 266,00 I believe on body don't know what motor has ,the jeep don't smoke but I am having problems with gas milage getting about 7 8 miles to the gallon and when I start motor for a second I here dry lifters even after recent oil change .just trying to increase fuel milage and keep on the road another year"

  • 2 more comments 
  • tlevine67 Apr 01, 2014

    that is 266,000 miles and 7 or 8 miles a gallon

  • kzone10 Apr 01, 2014

    Wow-266K!-but getting 7 or 8 mpg is definitely too low. The dry lifter noise is a bit of concern, sounds like the oil isn't getting to the top end of the engine right away-but maybe just after sitting for a while-and then goes away after oil pressure builds so not too bad. I really can't offer much more than the general maintenance upkeep I mentioned before. Best of luck!

  • tlevine67 Apr 02, 2014

    the jeep always got bad gas milage i am just now trying to increase the milage i would be overjoyed to get 17 per gallon lol

  • tlevine67 Apr 02, 2014

    my last fix a day or so ago was new rotor,cap,wires,and for dry start i added slick 50 high milage formula to fresh oil.and yea i get that occastional rough idle mostly after i have driven a bit and go to start back up .like say i drive around 10 minutes hit mickey d,s set a bit eat then after 25 minutes start up and runs rough at idle then when i get goin down the road theres no idle problem .yes its old and tired i,m just trying to get another year out of it and better gas milage .with me for some crazy reason my vehicles are inproved the older they get even get better in appearance ,the miracle of a quick can of spray paint here and there and it makes a difference lol


  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 20 achievements.


    An expert that got 10 achievements.


    An expert that got 5 achievements.

  • Jeep Master
  • 20,706 Answers

X2 the basics posted above.. as for ever...
2wd or 4wd, and what transmission????

7 mpg, 4.0L I-6 AMC engine.... the XJ jeep !
well its just a 89 Cherokee, made by AMC.
real Chrysler MPI, high output , starting in 1991...
the 89 has a 4.0 engine, with the horrid EFI that year,
(i owned 3) Great motor. for sure.. one was MJ .
the EFI on this car is Bendix/Renix, French fuel injection. junk.
and there are no scan tools sold for this in any store.
so you get to work blind.
no flash codes for the CEL lamp either (yes, pure H3LL EFI)
(unless you have DRB scanner cash to spend, i bet not)

all 3 of mine got 19 mpg, now matter what (all new cars then)
when not 19?, what caused this.? 7MPG?

in almost every case, the exhaust manifold cracked.
Stock car.... so... cant guess what you have....
mine was SST factory steel manifolds. and cracked.
and i had to remove them many times and get then rewelded
with SST rod. (now i own the TIG to do that , self)
i cracked on the inside part, were its not easy to see.
how did i find it, easy.
rubber hose to ear (3/8"id) and other end on metal rod.
i move rod (not get burned) and hear PUTT PUTT ,
yup, it cracked AGAIN, an AGAIN.

latter i found a contribituing factor the lower exhaust pipe
(all cars 5speed m/t)
the clamp was bad, allowing the exhaust system to swing like a pendulum. over stressing the exh man.
so i welded up a custom mount below bell housing to fix that.
helped big time.
what else.
bad MAP
what else, the stock POOR cat loves go break up and pack-up exhaust
and huge exhaust back pressure. (i switched to custom CAT that lasts, non OEM) (at 02 bung i can read back pressure easy)_

what cant you do.?
no watching your 02 oxy sensor stuck at 0v
causing RINIX to go nuts and huge rich.... over 40% rich or more.
in these years there was no limits on the TRIM.
no scan tool to see my LTFT (trim) is way off
no scan tool to see if my map is WRONG (clean it yet>>?)
no scan tool to see ECT read WRONG.
and more
yes, blind. sux.
sell it and buy a 1993+ (and win) RENIX sux , swamp gas.....
said by a guy that loves EFI, so,, there you go.

I have 3 other tools to allow me to work, junk like this car.
1: DMM
2: real scope.(oops the 02 is really stuck at 0v. fix that first)_
3: a DMM logger, i can log live data (amps and volts) even driving.

IF the map reads low pressure (vacuum is pressure in science)
here is the chart to test it.

if say the map sensor vacuum port or line leaks
the pressure goes to near zero. (14.7psi at sea level)
and 4 volts out.
and it will suck gas like mad.
clean every inch of the map parts. and win.
they usually never go bad only leaks. or clogs.

i got tons of facts on 1988 to 1992. EFI and more..
the good, bad and ugly....

Posted on Sep 08, 2015


6 Suggested Answers

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

A 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
The service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
Good luck!

Posted on Jan 02, 2017

  • 72 Answers

SOURCE: Gas consumption

My Answer:

Poor gas mileage can be a result of many many things.

First of all you need to find out what is the factory normal gas mileage for your model year Jeep SUV. It should have said on your window sticker if you bought it brand new. If you are a 2nd or 3rd owner then a Jeep dealer would have info. Google search will tell you as well, and only takes a couple minutes to find.

I did a quick Google search and for a 2003 Jeep Grand Cherokee with a (4.7L V8 engine) the average mileage is roughly 14 mpg.

Not sure what engine you have as to options, etc?

How you drive will greatly change that number up or down depending on a number of driving and driver variables.

A few being -

Driving habits?

Tire pressures?

Engine tuned up?

Lube & oil/filter changes (every 5,000-7,500 miles? Air filter changes (every 10,000-15,000 miles)? Read your auto manual for exact recommended intervals.

How many people in the SUV on average?

Are you towing anything?

Type gas you are burning - BRAND? (See injectors below)

Area you are driving in (hills and valleys verses flat out,

Jeeps in general don't have a good track record for great mileage, and rough engine idling is always a clue that your fuel injectors are dirty. Typical on all Jeeps with port fuel injection systems! On Jeeps with dirty fuel injectors your mileage will go way down accordingly. If your not putting at least a 12 oz bottle of say Walmart brand Super Tech Fuel Injector Cleaner (~ $1 each) in your gas tank religiously every logged 1000 miles, or every 2 tank fill ups, then you are just inviting dirty fuel injectors and POOR fuel economy!

My 1993 Ford XPLR with a 4L V-6 engine (and ~ 160,000 flawless driven miles) gets roughly 22 miles per gallon on the highway with cruise control on, and about 17 around town on average. I religiously put a 12 oz bottle of the above injector cleaner in my gas tank every 1000 miles!! Of course I do all my own tune-ups, general repairs, and suspension maintenance (shocks, O2 sensors, trans oil changes, lube & oil/filter changes, code reading and clearing, etc) myself and it shows! I don't trust repair shops except for say Tires and Balancing at SEARS.

Hope that helps ease your mind about gas mileage as it relates to your Jeep there.


Posted on Aug 13, 2008

  • 77 Answers

SOURCE: Jeep Acts Like Out of Gas- HELP!

it sounds like the engine isnt getting enough fuel. I would suggest changing the fuel filter and possibly testing the fuel pump to see if it is bad.

Posted on Oct 20, 2008

  • 6982 Answers

SOURCE: firing order for 1997 jeep cherokee straight 6 cyl.

153624 On cap #1 is two towers clockwise from right side hold-down screw, #1 is front cyl on engine. Firing order is clockwise.

Posted on Apr 15, 2009

  • 1 Answer

SOURCE: 1998 Jeep Cherokee - hard to start

My 98 Cherokee was the exact same. I used to have to turn the key back and forth 3 times and then it would start. Otherwise it would just crank and crank for a while and then start. Pretty embarrassing! Took it to the dealer and they said that my fuel pump was losing pressure. I changed the fuel pump and I don't have to prime the pump anymore.

Posted on Jul 10, 2009

  • 1 Answer

SOURCE: 97 jeep wrangler starts then stops right away

Had same problem with my 97 sport, after changing almost all of the ignition components, it turned out to be the TPS.

Posted on Sep 06, 2010

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

How to tell when o2 senser is bad

poor fuel economy is a give away as the CPU will not be able to correct the air/ fuel ratio. Run fault codes is another way.

Dec 05, 2013 | 1997 Chevrolet C/K 2500

1 Answer

Symtoms bad o2 senser

Black smoke out the exhaust and or poor fuel economy.

Dec 05, 2013 | 1997 Chevrolet C/K 2500

1 Answer

Impala o2 sensor

1. Reduced fuel economy
2. Increased exhaust emissions
3. Poor engine performance
4. Engine check light appears
5. Engine stalls during idling
6. A rotten egg odour emitting from the exhaust
7. Your engine surges or hesitates
8. Rich mixture

Jun 03, 2013 | Cars & Trucks

2 Answers

Can bad oxgen sensors create bad fuel comsumpution,rough idleing?

Hello jack_mathews,

Yes, an o2 sensor tells the computer if the exhaust gases or too rich or too lean. If the computer is told the by the o2 sensor that it's too lean the computer will increase the amount of fuel delivered to the engine thereby reducing your fuel economy, and if the o2 sensor is stuck on lean the computer will continue the increased fuel delivery.

The increased fuel can foul the plugs and cause a rough idle.


Mar 06, 2011 | GMC Jimmy Cars & Trucks

1 Answer

Torque converter clutch hang up

You mean the Torque converter Clutch Solenoid (TCCS)?
Its cheaper to replace it and your fuel economy will increase.
You could do this your self.

Mar 28, 2010 | 1996 Jeep Grand Cherokee

1 Answer

Runs Rough no catalatic converter

Well, i know that a took out a bad caat once and the truck ran terrible. So I went and put a new one in and it ran great. The O2 sensors can't read the exhaust gases correctly with out it. It was a Dodge with a 5.2L

Apr 19, 2009 | 1994 Jeep Grand Cherokee

1 Answer

01 expedition fuel mileage

If you gutted the cats it would emit a lot of bad emissions and a check engine light would definitely come on. I would try to clean the mass air flow sensor.

Oct 16, 2008 | 2001 Ford Expedition

Not finding what you are looking for?
Cars & Trucks Logo

250 people viewed this question

Ask a Question

Usually answered in minutes!

Top Jeep Experts


Level 3 Expert

79123 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22326 Answers

Kevin Daniels

Level 3 Expert

1455 Answers

Are you a Jeep Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides