Fuel Economy: '98 Grand Cherokee 5.9L Limited
 

Hey, I'm new to the forums and had a few questions.

I just recently purchased my first car - a 1998 Jeep Grand Cherokee 5.9L Limited.

I love this thing, but I'm averaging JUST shy of 400km per tank.

I'm ready to start my tune-ups, upgrades (exhaust, intake, etc), and was wondering if anyone has any information in regards to software upgrades, or any aftermarket solutions that would assist in boosting fuel economy. I'm convinced that there is a way to get more km out of this beast.

I'm hoping to get as much information as possible prior to spending any money.

Thanks in advance, hope to here from you guys soon!

-Jon

Re: Fuel Economy: '98 Grand Cherokee 5.9L Limited
 

The best way to keep the mileage up is to maintain the Jeep.
Tuneup's, fluid levels checked and clean, tire pressure correct, clean injectors. Biggest thing is to go light on the gas pedal. None of the Jeeps are known for thier gas mileage.
Exhaust, throttle body spacer, K&N (or equivalent), chips, will all net you about 2-3 mpg and 5-10 hp total.
A mild cam will net you between 8-10% hp & torque and the same 2-3 mpg for a quarter of what all the other mods would cost.
Also a big factor is altittude of where you drive and stop and go traffic. In McMurray in town I average 14.2 (20 mpg), on the highway to Edmonton 11.1 (25 mpg), at home around Pincher Creek I'll average 9.3 (30 mpg). (Highway speed 110km/h, in town 70km/h)
All mpg is calculated not by the trip computer.

Dan

Re: Fuel Economy: '98 Grand Cherokee 5.9L Limited
 

Also using a higher octane fuel will give you better milage and also be better for the engine because the fuel burns cleaner and will leave less carbon build up in the engine, but then you also have to work out if the more milage is worth paying extra for the fuel.

Re: Fuel Economy: '98 Grand Cherokee 5.9L Limited
 

Yep already using 91 octane all the time.

Thanks for the replies.

04WJGUY - Thanks for that info I appreciate it. You think you could give me a bit of detail on the chips and computer components you know of? I've tried doing some searching but I know nothing of them nor what to look for (and what not to look for). I live in Toronto, ON, so the pricing is very similar I'd imagine.

Thanks!

P.S. Definitely knew going into it the fuel economy wasn't the biggest advantage of the vehicle. I don't care - I love it - but I'm thoroughly convinced that I should be able to get this thing at about 450km per tank.

Re: Fuel Economy: '98 Grand Cherokee 5.9L Limited
 

Also another thing, take the stuff out of the car that you don't need, I see a lot of people driving around with the back of their car full of junk they don't need (people like me :) ), all this adds weight to you car which will also affect your milage.

Re: Fuel Economy: '98 Grand Cherokee 5.9L Limited
 

Hi HV,
I'm going to start by saying that this is my personal opinion.
Chips on a Jeep- pretty much 300-500.00 that you can better use for tires or other goodies. Hypertech, Jet, Superchips, Banks, Spyder all claim anywhere from 10-25 more HP and 30+ on torque. This is under ideal conditions (temp and humidity), in second gear. This is all at the higher RPM's where we normally don't drive unless your racing. Does not take into account being in the real world of wind resistance, trans in drive, etc.
Are they worth the money?, not in my opinion.
If you gain 2 mpg (9 L) @ $0.85 per/l you will have to buy 65.4 tanks of fuel or $4336.00 to have it paid for.
Kenne Bell and Kolak can do a ECM/ PCM re-program that resets when the computer goes from closed to open loop, from what I've heard they work reasonably well. But again they are expensive.

Dan

Re: Fuel Economy: '98 Grand Cherokee 5.9L Limited
 

What do you mean by this? It isn't worth dumping any money into trying to improve fuel economy because it won't make enough of a difference?

I'm selling this Jeep I have now, but I'm getting another one the exact same car. It's in mint condition and has about 25,000km less, and I found a wicked deal, so I'm jumping on it. AND it's black!

I still don't want to end this thread though because I'm definitely looking to add upgrades/tune-ups on the one I'm getting next!

Re: Fuel Economy: '98 Grand Cherokee 5.9L Limited
 

It's always good to try and improve fuel economy especially at the price it is at the pump nowadays, the point I was trying to make is that bolt on fuel and horsepower increases rarely do what they are hyped to do. If your lucky you'll get 1-2 mpg. Normally though you won't see any increase and your out lots of money.
Best way to keep mileage up is to keep up with the maintanence and go light on the gas pedal.
High flow cats, bigger exhuasts, air filters (ie. K&N/ Airraid) all help a bit with HP and torque but not mileage.

Dan