25 mpg in a 4.0 Renix 89 Jeep?

I am going to look at an 89 Renix, 2wd jeep tomarrow that I may buy. Only has 112,00 miles on it, and only 2 owners. The second, current owner bought it 18 months ago and says he gets 25 mpg highway and 16 mpg in the city.

It has an engine problem (still runs, but runs rough) and some mechanic told him the #5 cylinder is bad. So he is selling it, rather than fix it due to the cost of fixing it.
Lucky me I have a good Renix engine!:sunshine: Also, it might not be a bad engine, never know.

So here is my question, has anyone else ever gotten anywhere near 25 mpg with a 4.0 renix in a 2WD jeep?

I know several here have reported 20 MPG, but those might have been 4WD jeeps, which I am guessing get less mileage than a 2WD, and I am not sure if any of them were Renix jeeps (engines)?

I just have never heard anyone report 25 mpg on a jeep, other than my 2.2 L diesel of course but that is another story, so the question is with a 4.0 L Renix jeep what is the best highway mileage ever reported for a 2WD.

Yes the jeep is a box, but I get 34 MPG with my 85 Cherokee, 2.2 L Nissan Diesel engine driven Pioneer, so Jeeps can get great mileage, you just have sacrifice power :shiver: to get it.

My '92, 4WD, (not quite the same animal) was getting a hair over 23MPG, when I was using it on a 90 mile, one way commute a few years ago. Of course, I live less than a mile from the on-ramp to I-80, and was working less than a mile from where I got off. I was getting two days from a tank , but I did not exceed 65 MPH, and there were only four start-up cycles per tank. It was later in the summer, with reasonable temps, and here in upstate PA, you can tess by your gas gauge if they are selling summer or winter gas. Also, recent O-2 sensor, proper t-stat, gutted cat and Flowmaster noisemaker. It is possible, with 2WD being a little lighter, I guess, but as I've found out in 35 years of driving old heaps, sanity with the right foot is your best defense!

I got about 24 in a 90 I owned. Couldn't believe it cause it ran like crap! Really babied it to get that mpg. My 98 gets about 23. These are averages per tank so the highway miles must be at least a little higher.

I would regularly get 22-23 highway in a '90 4wd with 2 passengers on long trips. Got 24 once when driving alone. I guess 25 is possible with 2wd.

I normally get 20-21 with my 89 4WD XJ. Personal best of 22.9, but those are average miles 50/50 hwy/city. And that's with all the problems my XJ is having!! I'm sure if I could get the damn block to stay up at temperature, I could get up to ~25....

Bottom line?? 25 MPG in a 2WD Renix is totally possible.....not easy, but possible......

I just checked my daughters and while she was gone I drove it more then my yj and I got around 26 mpg but that was the first time I checked it. Plus this is still stock 4.0 with about 160k on it.

I got 25 once on my 4.0 4wd 5-speed. On a recent trip I got 23.

I get 23mpg highway in my 4.0l Renix Comanche 4wd. But it has a manual tranny and 3.07 gearing. Plus I drive it so slow grandpa passed me.

I got 23 in my 88. Before the lift, tires, ls difs and gears. Now with 160K miles I get 20.

I got right at 25 mpg with my 89 4WD on it's first trip after buying it. Surprised the heck out of me because I didn't think it was possible. Double checked it later and that was indeed the highway mileage.

My 'new' 96 dosen't get as good....probably around 21 mpg highway.

Well I just got back from looking at it. From the looks of it, top to bottom, it looks barely used in spite of the years. Unless the seller changes his mind I should be buy it tomorrow for $900.00. I am going to start a new thread on the engine problem I found with it. He is selling it because it has miss, shakes bad at idle, etc., and a mechanic he had diagnosis it told him the #5 cylinder was shot. I not convinced of that yet. See the new thread I am starting for the details on that.

Anyway, I am amased at how many have reported great mileage in this thread in the 25 mpg area, so I guess it's not just a legend, these beasts can get great mileage!:clap:

So keep reporting your highest mileage in this thread please, I am sure it will be useful to many others of us who had been trying to figure out what mileage we should be targeting when tunning these beasts up. I have an 87 4WD that I am running out of things to replace on it to solve the horrilble mileage I was getting with it when I bought it (8 to 12). Knowing that it can reach 25 mpg is most encouraging! Thanks!

Ecomike said:

I am going to look at an 89 Renix, 2wd jeep tomarrow that I may buy. Only has 112,00 miles on it, and only 2 owners. The second, current owner bought it 18 months ago and says he gets 25 mpg highway and 16 mpg in the city.

It has an engine problem (still runs, but runs rough) and some mechanic told him the #5 cylinder is bad. So he is selling it, rather than fix it due to the cost of fixing it.
Lucky me I have a good Renix engine!:sunshine: Also, it might not be a bad engine, never know.

So here is my question, has anyone else ever gotten anywhere near 25 mpg with a 4.0 renix in a 2WD jeep?

I know several here have reported 20 MPG, but those might have been 4WD jeeps, which I am guessing get less mileage than a 2WD, and I am not sure if any of them were Renix jeeps (engines)?

I just have never heard anyone report 25 mpg on a jeep, other than my 2.2 L diesel of course but that is another story, so the question is with a 4.0 L Renix jeep what is the best highway mileage ever reported for a 2WD.

Yes the jeep is a box, but I get 34 MPG with my 85 Cherokee, 2.2 L Nissan Diesel engine driven Pioneer, so Jeeps can get great mileage, you just have sacrifice power :shiver: to get it.

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I get 17 out of mine right now but then again I'm stroked, with 4.11's and only got a little over 300 on a fresh rebuild. I had a 99 2wd and got 27 high way out of it but that was on a stop only for gas trip. For the most part it was around 23 though and 16 around town depending on the weight of my foot at the time.

w_howey said:

I get 23mpg highway in my 4.0l Renix Comanche 4wd. But it has a manual tranny and 3.07 gearing. Plus I drive it so slow grandpa passed me.

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My 89 Comanche has the manual with the same gearing and got 21-22. Then swapped in 4.10 axles, lifted it 5.5", and put on 32s and that dropped to 18-19. Now with an auto in there I'm getting 17.

Well it's official mine now. Bought it yesterday. All the latest problem, debugging details are now at:

http://www.naxja.org/forum/showthread.php?p=243606834#post243606834

Thanks for the high mileage feedback!

I make runs to downtown San Diego from north OC (about 200 miles round trip). Even with my heavy foot, high freeway speeds (70+) and the A/C on in the summer, I get about 22ish MPH. I suspect if I throttled back, took it easy, and avoided the 73 tollroad, I'd get close to 24ish. This is on my '88, 2wd, 175K with a cracked exh manifold.

Well I still need to do the head job on this one that I bought and posted about here that got a reported 25 mpg by the prior owner......, but in the mean time I just confirmed the folowing on my 87, 4x4 stock project that has plaqued me for 2.5 years with regular problems, and repairs including horrid mileage at first.

I confirmed my highway only mileage today on a city freeway, with frequent overpasses, not a straight flat road so it should be even better on a straight flat road, but there was no traffic so I was able to drive 48.2 miles, 99% freeway at an average of 60 mph, with a 55 mph min, 65 mph max speeds.

I topped of the tank first, until it spilled over, and topped it back off three times at the same pump, same station after the freeway trip. If I use the first gas shut off value I got it calculates to 26.34 mpgs, if I use the second pump shut off value I got, it calculates as 20.51 mpg, and the third pump shut off value which overflowed again calcualted at 18.54 mpg.

1st = 1,83 gallons
2nd = 2.35 gallons
3rd = 2.6 gallons (overflowed before shut off)

If I estimate the full tank at 2.45 gallons, just before it overflowed, I get 48.3 / 2.45 = 19.67 mpg, then times 1.02 for the tire size speedometer error, I get = 20.07 MPG!!!party1:

So I have officially joined the 20 mpg freeway/highway mileage XJ club!!!party1: :yelclap:

I am still only averaging 14 mpg due to the traffic and stop sign congestion in the local city DD routine, but that is a far cry from a low of 6 mpg city only, and a high of 12 mpg highway only at it's prior worst.

The 2 most significant improvements came from a new TPS, new ground wires for the TPS, and a new O2 sensor. Tune ups and new fuel injectors had helped with the rough running low power operation and may have helped with the mileage had the TPS and TPS grounds been good to begin with.

Lucky SOBs!!:bawl:

The MPGs on my '97 have always sucked!! Even though I've never really checked it on a road trip (I don't get many in), I'm delighted if I get as much as 16 MPG around town!!

Oh well..... at least I know I'll get there no matter what!!! atriot:

crystalship1 said:

Lucky SOBs!!:bawl:

The MPGs on my '97 have always sucked!! Even though I've never really checked it on a road trip (I don't get many in), I'm delighted if I get as much as 16 MPG around town!!

Oh well..... at least I know I'll get there no matter what!!! atriot:

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16 mpg city is great! I am lucky to get 14 mpg city, mixed local/highway. But I have finally hit 20 mpg now on straight highway, nonstop run after nearly 3 years of hard work. I have a DD, first thing in the AM trip with 36 stops signs in 1 mile round trip, averages about 8 mpg on that trip if I am lucky. That kills the rest of the DD mileage for me.