Eco modding the Jeep TJ to 5.5l/100 (42MPG)

[oldtamiyaphile]

I finally go serious about my TJ Jeep Wrangler's fuel economy and decided to do something about it:







So I sold it and bought a Suzuki Jimny

The latest Jimny is still exactly the same size as the US market Samurai of the 80's-90's. It's virtually identical in size and interior space to the TJ Wrangler, if you exclude the Jeep's long bonnet to house that I6.

So 18mpg (mostly highway) became 42mpg (mixed), which should still increase once the car loosens up.

The drive experience isn't all that different, but the Suzuki is at least a little better in every way. The main improvement (after economy) is wind noise. The TJ (hardtop) would howl at 30mph and get worse from there. Since you have to drive highway miles to get to the off roading it made the whole car a little pointless. The Jimny is still live axle at both ends, it it's at least livable. Driving the TJ, a bump at the front would seem to upset the rear axle too. The Suzuki seems to manage better despite the much shorter wheelbase.

Suzuki have done a stellar job of the newest Jimny. It's like an off road MX5 in that all the controls are perfectly weighted and positioned. It's light weight to the exteme, even the ECU is only about the size of a smart phone.



Plenty of room to work

[M_a_t_t]

It looks sharp. If it was available in the U.S. it would be on the list of new cars I'd actually own

[MeteorGray]

That is a capable replacement for the ole TJ, with a GIANT leap in fuel economy. Is it diesel? Congrats!

I'm sticking with my '03 TJ. It's been a reliable ride for me, and with the "Aussie" lunchbox locker I installed in the front diff, it's really outstanding in the mud I have to get through after turning off the pavement trying to get to a hunting spot

I get maybe 16mpg on the pavement to reach the mud with the mug-lug tires, so it's a good thing fuel is cheap around here.

You may need a set of lugs for your new ride if you get far off the pavement. That would trim your stellar mileage a bit, but it will still be leagues ahead of my ole tough-but-hungry straight-6.

And yeah, my hardtop ain't "quite" by a long shot, but you should have heard the drumbeat I had to endure when the ragtop it replaced began booming at speed on the road. You could hardly hear the screaming mud grips outside. :-)

[oldtamiyaphile]

It's a 1.5 petrol. The early fuel economy is pretty staggering, especially since I typically see a 5-10% improvement after the first 6K miles or so.

It's a bit gutless compared to the 4.0, but I really hated the ECU mapping on the 4.0. You can really tell it's a 70's engine that's been dragged into the 21st century. Too responsive and jerky off idle, but then gutless in the lower-mid range, really strong at 1500, but then out of breath not long after.

The little Suzi needs revs but it's so smooth and linear by comparison. AVO do a turbo kit that's not too expensive or I'm thinking of an E-Charger for maximum low end.

I had my '05 TJ from new and only did 20k miles in it. The problem was always by the time I'd get to the off roading, I'd be all beat up from the trip and then still had all the rough stuff ahead of me.

We don't get much rain here so I can live without M/T's. I'm more leaning towards having a set of street tyres and a set of A/T's. Live axles make jacking as swapping tyres pretty easy.

Some owners of lifted, modified Jimnys (the biggest legal tyre size here is only 29-30") report only about 20mpg, so there's no such thing as a free lunch I guess.

The main issue I have is it don't have a rear LSD like the TJ did, it's got TC based LSD on all fours by that really waits for you to get stuck before it helps out out Makes for very jerky progress in axle twisters.

https://youtu.be/vApUZM5l2JY?t=1835