I've got a 2000 tj 4.0 automatic I get about 13-14 mpgs per tank. I've heard that upgrading your distributor cap and spark plug wires is a sure way to gain HP and MPGs. Wondering if anyone has tried this and seen any noticeable results. I would also like to hear any other suggestions or results of chips, cold air intakes, gears, etc. I would be tickled to get 16-18 MPGs but any info about any of these options would be greatly appreciated.
There are lots of threads discussing all this crap. Use the search and read to your hearts content. Short answer is very few, if any, of them are worth the work. Best ways to improve gas mileage are to change driving style and to shed weight.
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The mod you are thinking of is for the 4.2L, not the 4.0L.
You drive a brick on wheels. Go easy on the skinny pedal, air up your tires, keep the engine tuned up, grease up the u-joints regularly, lighten up the load you carry, avoid short trips if possible (give the engine enough time to fully warm up to operating temperature), regear to an appropriate ratio for your tires and driving habits...
use inertia to your advantage. Inertia is the energy required to move an object at rest, to chance it's direction when in motion, and to bring it to rest while in motion. When you are coming to a stop let up on the gas and don't use the brake until you either have to or slow down enough as by using the brake you loose the potential energy that you have built up. This also works when taking an exit on the freeway. Time your speed with distance it takes a while to adjust but it works and your mileage should improve slightly. As far as using a chip what it does is gives the engine more power. With this power you can ease up on the gas as you will have the power to do so. A free flowing intake and exhaust also makes the engine gain power that combined with the chip you should be good for a mile or 2 per gallon. It's not a waste of money by doing those mods your making it easier for your engine to breath and exhale better and this will improve the life of the engine and make you a
gain some efficiency which turns into MPG gains. Don't look for a huge MPG gain it will not happen as with HP gain there is wallet losses.
Like I always said a car with a 2 barrel carb will get less mileage than a similar care with a 4 barrel carb because the 4 bbl carb has more power and you can back down on the throttle to get better results as a 2bbl carb.
You could do many things and they will pay off, but it depends how long you're going to keep your vehicle, some may pay off after a few months, some may take a year and half.
Unless you're looking to cruise at 75mph and better that brick styling has no effect, aero issues don't come into play until beyond those speeds, as wittnessed with the TG tests on myhtbusters, no diff at 55 mph, except when they lost the weight of the tailgate on the truck.
...Unless you're looking to cruise at 75mph and better that brick styling has no effect, aero issues don't come into play until beyond those speeds...
The Myth Busters test with the pickup and the tailgate is a completely different from most of our Jeeps. A pickup has better overall aerodynamics than a TJ, esp. a lifted TJ with larger tires. The typical pickup sits closer to the ground, has its narrower tires tucked into the body better, a more curved shape on the front and the windshield,...
A TJ has flatter, more vertical surfaces. A lifted TJ has more wind resistance than one with stock suspension. The wider, more exposed tires add to the frontal surface, as does the front axle. Everything about a TJ screams " Look at my aerodynamic drag!” I see increased fuel consumption as I go past 60 MPH. I will sometimes hit 70 mph because of traffic, but seldom higher. I usually cruise at 65 MPH.
I quit being in a hurry many years ago. Leave early, enjoy the drive.
Keep in mind that free advice can frequently be worth less than you pay for it.