XJnumero3

So i went and bought myself a flashpaq 3875 for my 1999 XJ and it does not come close to what i want. I'm a firefighter in the high country of colorado so i'll be burning down the highway at the speed limit of 75mph(exactly the speed limit, never over. Never... ) and i've got to maximize my fuel efficency.

I need help picking a reader please! any other advice would be really good.

I want options for Mileage, Towing, overall performance monitoring and Using 87/91 Octane. A real time display would be SWEET but i realize is hard due to the age of my XJ. Some kind of computer support (windows 7 compatible, preffered) would be superb.

I'm willing to pay more but i need to know what would be best! I would love one with a display that was responsive.

What options do i have>?

Thanks for your help

bassboost

From what I know, these Jeeps just aren't that fuel efficient haha! Things you could do..

-Tune-up
-Gears
-Not sure if a programmer is going to help much!
-You already have intake & exhaust
-Perhaps getting more involved with the motor to produce more flow?

Bustedback

So, you want some cake, and you want to eat it too? You're expecting too much out of a chip and a 4.0.

88_cherokee

a stand alone ecu properly tuned would help a lot

OEJ

prolly the only way is to make sure she's fully tuned up. a nice high flow exhaust and a stand alone.
mpgs and xj are a contradiction in words. thats about the best you can do. our xjs get the best mpgs @ around 2k rpms.

thank you for ur service. seriously.

XJnumero3

Thanks OEJ. Hate to pimp my Fire Status but i'm hitting some serious walls with forum. i'm not looking to put a four foot lift on my cherokee, i'm looking to cherry it out until i can make it my hobby from my DD. I guess i'm in a unique category.

I REALLY like the idea of a NEW ECU, where's the best guys? or can i get mine evaluated? Or Tuned?

OEJ

your welcome.

I would start with 505performance.com
and give them a call. they could atlest turn you on to a good stand alone manufacturer. get urself a air fuel gauge and a vac guage too. keep the vac guage as high as poss while driving and that gives better mpgs. you gotta make her breath first.
Change the dif oil front and rear and t;case while there. i used royal purple. also use it in the motor too.

Mean while you could do some free mods to make her alitle light. remove the body molding. the roof rack. get some plexi head light covers. remove the back seat. remove the jack and spare and put a tire repair kit and an mini nair pump. remove the carpet and lizard skin the floor for sound deadning.

it won't reinvent the wheel, but i got a 1mpg gain for just the removing the roof rack.
if i think of anything else, i'll let u know.
but i'm sure all ur gear will offset this, but it will still be lighter.

OEJ

good luck.

CobraMarty

-Get an 'ultra-gauge.com' it has all the features that you are looking for, reasonably priced $70

-2.5" cat back exhaust, new cat if over 100k $150
-Volant CAI used $125, new $225
-normal size street tires for XJ, not 30"/31" more like 28.5" or so.
-make sure your speedo is accurate, check against GPS, correct if needed $30 if need a new speedo gear
-synthetic engine oil, trans oil, transfer case and diffs $100
-ignition tune up- plugs, wires, coil, cap, rotor. Check Ebay for perf ignition upgrade $80
-62mm bored throttle body $100-125
-1.6 or 1.7 ratio Yella Terra roller rocker arms $425-480
-ecu tune(NO standalone)- contact FlyinRyan at jeepstrokers.com $375 with handheld tuner and unlimited tunes
or Christuned or sidewaystarion? at NAXJA.org $250

-lose the extra weight and slow down. It takes 10% more fuel to go 65mph vs 55 and 25% more fuel to go 75mph vs 55!

OEJ

^^^^
really?.. yeah like i said. lol,

MINUS the the roller rockers, while it ill increase power, wich your not looking to do; it DEcrease mpgs.

CobraMarty

Increasing efficiency and decreasing friction, Will increase mpg. At his desired speed, he does need a bit more power.

Have you tried a set of YT roller rockers? How do you know they will decrease mpg?

OEJ

I was being a smart guy, because the power increase will add weight to his foot..but true, if you can keep you foot out of it.

I had a fox body mustang with 1.6s in it,not to mention some other basic mods, and i just could keep my foot out of it.lol.

sorry for the confusion, i meant to right that post like i was joking, but got distracted.

CobraMarty

Crf136n

So first off I agree these are not the most efficient rides out there...not knowing what you are working with as far as current economy, target economy and vehicle I dont think investing in all these electronic gizmos is going to be worth while. Keep it simple...intake/exhaust and TIRES...rolling resistence is your enemy.

I have a stock '87 4.0 automatic with 242k on it 3:55 gears and 215/75-15 tires (they were free lol); and its in good tune. Commuting over a twisty mountain pass 4,500-9,000ft every day plus a little city and a little highway I average 17.5-19 (gps odometer);

I also have a '96 4.0 with 235k on it, was an auto but just swapped to manual, but with auto trans 3.55 gears and 32" Dunlop Mud Terrains - high flow intake, airaid TB spacer, borla headers, dynomax exhaust, and in perfect tune with the auto was getting consistant 18-18.5 mpg (also gps odometer) same driving conditions; occasional dirtbike on hitch rack so an extra 300 lbs with gear a couple days a week..havent drivin it enough with stick shift to run through the tank yet for calculation. Jeep also has full yakima roof rack and a light bar. The Dunlop tires combined with the aluminum Ultra Nomad wheels are very surprisingly lightweight which may be contributing.

I once had a stock '87 2wd 4.0 comanche with a 5-spd and 3.08 gears that averaged 20-24 mpg.

All said I can be an aggressive driver but try to avoid excessive high revs, etc. I dont use anything exotic for tune or oil, just standard oem replacement stuff and I always run Valvoline Max Life 10/30. It may behoove you to throw new oxygen sensors at it, even if they arent tripping a check engine code yet as they can make the thing run very inefficient as they wear out. 65 mph I have found to be my jeeps happy spot with economy. Taller tires will reduce engine revs at freeway speed a bit helping to save fuel, but wider tires will offset that with more rolling resistance. Try this stuff before the overpriced re-mapping tuners, etc. Id say if you can get in the 18-20 mpg range you would be doing good...if you want more than that it may be time to start shopping for something else

pmichel

Speaking of gearing: Is ANYONE running a 4.0/AW4 with 3.07 gears? If it can gain 2-3 mpg over 3.55's, is it as simlpe as replacing the ring and pinion setup (i.e. on a stock D30/35)?