dollypup

my 97 cherokee gets 13.28 mpg.it is a six cyl,same as my 89 cherokee,which got 21 to 25 mpg.i put in new plugs and cleaned up the rotor,(which is about all i know how to do) and it didn't help.what needs to be done to get decent mileage?

nick_n_ii

Might want to try changing the O2 sensor, even if it don't send a code, it can still be bad.

Also you try running any fuel system cleaner through it?


And on a side note on my ZJ with the 4.0L I drop from 17 mpg to 12 mpg if I use gas that has more than 10% ethanol in it... SO watch where you get gas that might have something to do with it also..

Metmknice

I would say finish up the tune up. cap/rotor are cheap, plug wires are fairily also. Fuel filter, new air filter, check your egr valve also.

luckylewk

Tires inflated??
Oil changed??
TB cleaned??
Air filter clean??
Plug wires??
Clean and flush the radiator??
New thermostat??

EVERY oil change I run a bottle of fuel system cleaner, then one in between. Ive been told that the throttle bodies, especially in the I6, and other intake parts can get all gunked up and kill your mileage. Go run a couple bottles back to back in a full tank of gas, probably will help.

Also, if its cold out, you can take a piece of cardboard and sitck it in between the radiator and the condenser coil, that will help as well. Last year I took a piece of heavy cardboard, put a couple coats of black Rustoleum on it, cut a square hole in the middle a few inches across and basically bungeed it to the front of the radiator behind the grill.

All in all, no matter what you do mileage is going to go down a little in the winter months, but if you do a few things before it gets cold it can help.

BowtieGuy3

Check the O2 sensors (Leading and trailing), that happens to my 98 a lot. I also seem to have a problem with a b*tchy MAP sensor every now & then. It won't throw a code, but it runs like hell.

nick_n_ii

Bowtie, if your map is acting funny you might have a random vacuum leak...

I had that on my ZJ..

Seems most all problems you could have I have had....

BowtieGuy3

Yeah, we both have Jeeps....

Jsny1010

Bowtie...

The MAP how bad was your gas mileage? I just swapped the plugs, wires, and a new O2.. is it worth it to swap my map sensor? seems easy enough. or new coil/fuel filter?

mine runs GREAT! now but its still around the 15mpg mark i heard 18 was a LOW but hell at 20 years old i dont expect much

BuckB91XJ

After you have done all the tune-up stuff, if you're still not seeing the better MPG. If you're still running your stock air box, pull that POS noise reduction donut thing out of there and get some air coming into your motor. Also a header and cat back exhaust will help. The problem with the newer Jeeps is the factory was more worried about emissions than good running.

BowtieGuy3

Went from about 18mpg to about 11mpg. No, its not worth swapping it out unless you have another Jeep there with one that you know is good. (That lil bastard costs about $100) I think I have testing directions somewhere... Lemme check and I'll post..

blank87

K&N Cold Air intake. I got +3 miles after I installed it.

Phil99

Just out of curiousity, does your cold air intake have a heat shield

blank87

Yeah, mine came with the kit. As I believe they all do.

sandstone

A good fuel system cleaner (I use Gumout or Sea Foam) will help, especially with cleaning the fuel injectors. Also spray some into the throttle body, especially in the Idle Air Control passage.

sandstone

How long have you had the K&N CAI on your cherokee? I've been thinking of getting this for a while. So you're happy with it's performance?