Tuning an XJ Cherokee 4.0

[The Nicho's]

Hey guys my wife has a slightly modified XJ cherokee with 31's and im trying to get the best fuel economy i can out of it. Is there any tuning tips anyone can give me or anything i can do to it to make it run better. It gets a 5000k service and after every run i check the whole car over but i just can't seem to make any improvements on the fuel economy no matter what i do.. Fuel filter I'm told is in the fuel tank, can you change it easily??? It has a Safari snorkle and i regularly clean/replace the air cleaner, The plugs, leads, dizzy cap, rotor button are changed more than i should but it never makes a difference on economy..
Any suggestions or ideas would be greatly appreciated.
I know the old 245 hemi are thirsty but there has to be a way to get more km's for your dollar when ur paying $1.60 a litre without putting it on gas (NOT IN A MILLION YEARS).
Cheers
Nicho

[Steve F]

What sort of mileage are you getting?

Cheers
Steve

[layback40]

Its all to do with how hard you sink your foot on the accelerator. I have my diesel's instantaneous fuel consumption always displaying. It makes you drive much more economically.

[Toff]

Originally Posted by The Nicho's

I know the old 245 hemi are thirsty ....
Cheers
Nicho

Yeah the Hemi 245 is a bit thursty just like the AMC242 can be.
(Calling your XJ donk a hemi is akin calling a Ford 5L a Holden 5L)
anyhoo my random suggestions for better fuel consumption are
Run narrower tyres where possible for less road friction
Use alloy wheels as wheel/tyre weight is a killer on fuel consumption
Run a H/T tyre
Run slightly higher tyre pressures
Don't carry all your uselss junk about for everyday driving
Lower it? Yeah whilst this would help I guess you won't want this one
Get your injectors replaced or cleaned.
Ditto with your O2 sensors.
Give the exhaust system some loving. Old cats/mufflers can choke the airflow.
Replace the fan clutch with a thermo fan
Tell her to put her foot down less is probably better than telling her to get on her bike

[The Nicho's]

(Calling your XJ donk a hemi is akin calling a Ford 5L a Holden 5L)
Point taken.. The missus is light footed but she is getting at most 400kms to a tank. Injectors + O2 sensor, didint think of that I'll get em out and give em a clean or replace as needed. Exhaust was next on the list so i'm thinking I'll do that after the injectors and O2 sensor just so i can tell if 1 or the other makes a major difference.

Having a second set of tyres is not economical so she can stick with her muddies the $$$ spent wouldnt be saved in 12 months im thinking.
Tyre pressures are at 40psi so i wouldnt think higher would be good for even tyre wear.
Dont trust electric fans so won't be going there I'll just double check the clutch fan is working right.
I'll give it all a go during the week when i replace the rear wheel bearings and post my findings here.. The exhaust might take a few weeks to save up for so the difference there wont be known until then..
Thanks for the tips guys appreciate it.
Nicho

[The Nicho's]

Would any chip upgrades worthwhile for the XJ's or am
I barking up the wrong tree???

[Oli-dogg]

Here's a few other random ideas that may or may not work:

Throttle-body spacer -
http://go.jeep-xj.info/HowtoTBspacer.htm

Change either the speedo gears or the diff ratios to suit your 31" tyres -
http://go.jeep-xj.info/HowtoSpeedoGears.htm

Drive with a vacuum gauge -

http://www.youtube.com/watch?v=MBYVZLRyQjk&feature=related