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5jeepsIn12years 03-12-2013 01:49 PM

help XJ gas guzzling fire fighter! Flashpaq 3875 not worth it. What options?
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... :shhh: ) 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

Cleaner13 03-12-2013 02:38 PM

Im just curious what results you did get from the superchips? I know this isnt going to be any help nor is it what you want to hear, but traveling at 75mph in these boxy jeeps severely cuts down the mpg
what mpg are you getting already?
Im sorry that Im honestly no help, but maybe someone will chime in with tuning experience of some sort...

what is it you are looking to monitor? There are always "scangauge 2" I believe that has real time monitoring, although it will not contribute power or fuel, just monitoring alone..

5jeepsIn12years 03-12-2013 03:37 PM

Well my mileage now on highway is like 18/ 14 on "city".

CJ7-Tim 03-12-2013 04:36 PM

Tuner boxes and chips have little to no effect on the Jeep 4.0L. The 4.0L does respond well to old school hot-rodding stuff; cat-back exhaust, free-flow cat, header, bored throttle body, K&N type air filter, but do not expect any mpg gains.

You are driving a brick shaped 4x4, your best mpg's are when you keep it under 65 mph.

5jeepsIn12years 03-29-2013 08:08 PM

yea, i gathered all that. My third Cherokee so i wasn't expecting to turn it into a toyota prius or anything but i gotta respond to my station for wildfire season. Quick is preferred and where i am in CO is 75 mph so i use all 75 mphs... I'm gonna do all that hot rod stuff. returned the Flashpaq for a Flowmaster 2822225 282 Series 2.5" Universal OBDII Catalytic Converter. gonna do the headers, throttle body already got a griffin catback and a k&n but might go with a spectre air and a borla cat back.

I dunno i might do new ecm, gears, headers, alternator, paint flames on the side... sigh i dunno. i have to think HP will increase mileage! I keep seeing people on here saying they get like 20/18! like wtf! I CAN BUILD IT! MWUAHAHAHAHAHAHAHA Just Empty Every Pocket... maybe a supercharger or turbo charger? Perhaps if i ran it off rocket fuel... fml

Azzy 03-30-2013 07:55 AM

You may see some gains if you drop weight... if you done need 4x4, perhaps conversion to 2wd might be good if you insist on an XJ.

habbyguy 03-30-2013 08:32 AM

I'm getting 24mpg on the road, and a whole lot of that is at 70+mph (living in AZ). But I also have a five speed and 3.07 gears and 31" tires so I'm turning about 2,000rpm at 75mph. The only things I've done to improve the gas mileage are two-hole injectors, a header, and a new O2 sensor (plus synthetic lubes everywhere). I'd be really surprised if a tuner would do much for my XJ, but it's OK because I am very, very happy with both the power and economy I'm getting out of my good ol' iron I6 already.

5jeepsIn12years 03-31-2013 07:03 PM

Thanks, Habbyguy. That's sounding really reasonable. Two-hole injectors are Fuel injectors i assume? i was toying with redoing those. I'm slowly buying parts but i had a Banks header in my sights, NEW gears and new 02 sensor with an air/fuel gauge in A-pillar along with a vac gauge. Over here in CO, gotta get doing to this during mud season and while the mud ain't swamping us out... which good for my fire career i'm sure it aint!

habbyguy 03-31-2013 08:25 PM

Yeah, the injectors are two-hole fuel injectors (don't recall which type, but they seem to work well). I can't say they really made a dramatic improvement, but I figured with the price of gas and the number of miles I put on my XJ (220,000 now) they'd pay for themselves even with a very small improvement in performance and economy. If I had it to do over, I'd opt for 4-hole injectors, BTW. I did go with a cheapo Ebay header, which has worked out great so far - it "looks" like it would flow pretty well, certainly a whole lot better than the fragile cast iron appliance it replaces. A vacuum gauge is the easy (read "cheap") way, though a A/F gauge would be seriously cool too - probably won't allow you to actually DO anything about the mixture, but at least you'd see if something went south.

I've thought about replacing the exhaust system cat-back, but figure since it's original (yes, 220,000 miles, but this IS the desert!) and louder than it used to be, there has to be less restriction than there was. Heck, I was driving home from Home Depot yesterday with some big honkin' cabinets in the back, and the hatch open a couple feet, and it actually sounds GOOD. Hard to beat that for the price ($0). Besides, I'm pretty sure if I put real money into an exhaust system, I'd probably rip it out the first trip into the desert (these rocks have NO sense of respect for new parts, but seem to leave the old ones alone).

5jeepsIn12years 03-31-2013 08:50 PM

injectors sounds great! thanks for the idea. 4 holes, copy, thanks sir. i'm at 150,000 with my XJ and i want it for my hobby(i'm 28 so one of these days it wont be my daily driver) so i'm going higher end on parts but i see noticable response from the things i've done. A Cold air intake is a good idea as well. the stock box is kinda archaic! i'm gonna have a K&N CAI, extra in a few weeks here. In case you're looking

check out amazon, i use it because i'm up in the high country here and in addition to usually free shipping their prices are ALOT better than store and specialized part houses like quadratec. Flowmaster is having a sale and if you buy it from amazon they'll take off another 25% in addition to the 23% you're already saving. a thought for a new muffler

habbyguy 04-01-2013 08:26 AM

I'm pretty pragmatic about the updates I do on my XJ, especially now that it's got 220,000 miles on it (though I'd head out for South America in it tomorrow). The reading I've done on the K&N filters scared me off them (though my recently-purchased motorhome came with one, and I haven't changed it... yet). I live in a very dusty, sandy area and would rather give up a little performance and mileage to keep grit out of my beloved 4.0 liter motor. The consensus seems to be that a CAI will help, but a lot of them just suck in the same hot engine compartment air that your stock box does. I opened up the radiator / headlight support panel directly ahead of the air box intake on my XJ, which should (I believe) allow outside air to be pushed into the air box. It certainly hasn't hurt.

In the end, I'm thrilled I'm getting 24mpg on the highway, normally at 70+ mph. I consider that pretty darn good for a good-size, lifted vehicle with the aerodynamic profile of a shipping container.

AmbuGrl 04-01-2013 12:46 PM

I used neon injectors, 4 hole.

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