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Unhappy with MPG - looking for ideas

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aldo98229

aldo98229

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Actually, you guys got me thinking:
  • I was getting 17.5 MPG on my JK Rubicons on 35s, which had 4.10 gears
  • To be getting 15.2 MPG on a JL Sahara on 35s with 3.45 gears suddenly doesn’t seem totally out of line
Granted JK and JL are apples and oranges. Nevertheless, extrapolating: if I were to re-gear to 4.10 I’d likely see ~ 17 or 17.5 MPG; with 4.56 I’d probably see ~ 18.5 MPG.

This gives me a good view of the hole I’m in. 👍
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Actually, you guys got me thinking:
  • I was getting 17.5 MPG on my JK Rubicons on 35s, which had 4.10 gears
  • To be getting 15.2 MPG on a JL Sahara on 35s with 3.45 gears suddenly doesn’t seem totally out of line
Granted JK and JL are apples and oranges. Nevertheless, extrapolating: if I were to re-gear to 4.10 I’d likely see ~ 17 or 17.5 MPG; with 4.56 I’d probably see ~ 18.5 MPG
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So you don't think 15-17MPG is possible with 35s and re-gearing?
He was already getting that before his issue came up. His issue has nothing to do with gearing because it occurred suddenly AFTER MONTHS of expected MPGs.
I'm saying that he was at 20MPG when he had 33s on it. Then he went to a heavier and larger tire/wheel combo and I believe he would have been getting around 15-17 for months (based on one of his posts) before his issue came up. Then his issue came up where he was down around 11-13MPG which is occurring REGARDLESS of his gears. So back to the 15-17MPG that he was already getting on the stock gears... if he re-gears to 4.56 he will see 7th and 8th gears much more and get a couple MPGs out of that.

EDIT: LOL! It sounds like we are all in agreement in some backwards ass way. The expectations would be around 18MPG with a re-gear which as I pointed out is really only a 1-2MPG boost. Remember, in terms of what you gain out of re-gearing, we aren't working off of the 11-13MPG he was getting all of the sudden (at least I wasn't). We are working off of the 15 or so MPGs he was getting prior to his wacky issue.
 
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He was already getting that before his issue came up. His issue has nothing to do with gearing because it occurred suddenly AFTER MONTHS of expected MPGs.
I'm saying that he was at 20MPG when he had 33s on it. Then he went to a heavier and larger tire/wheel combo and I believe he would have been getting around 15-17 for months (based on one of his posts) before his issue came up. Then his issue came up where he was down around 11-13MPG which is occurring REGARDLESS of his gears. So back to the 15-17MPG that he was already getting on the stock gears... if he re-gears to 4.56 he will see 7th and 8th gears much more and get a couple MPGs out of that.
What I’m getting from all this, is that my current situation is the cumulative effect of (a) 35 inch tires, (b) improper shift calibration, (c) insufficient gearing, all of which were recently exacerbated by (d) winter gas blends.

My expectation would be to get from the 14-15 MPG I am currently getting, back to 16-17 MPG in summer.
 

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Have you tried just using manual mode on the shifter? That's how I drive mine. Went from 17-18 to 21-22 mixed. If you let it get up to speed in auto mode, then go to manual and up shift. Simple to try and see if your mileage increases.
Then you will know if you need a trans calibration.
With the 35's mine does not like to use lower rpm on the motor. Always wants a lower gear then needed.
 

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What I’m getting from all this, is that my current situation is the cumulative effect of (a) 35 inch tires, (b) improper shift calibration, (c) insufficient gearing, recently exacerbated by (d) winter gas blends.

My expectation would be to get from the 14-15 MPG I am currently getting, back to 16-17 MPG in summer.
You can easily fix all that. You will definitely enjoy the gear change while you're at it.
 

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Have you tried just using manual mode on the shifter? That's how I drive mine. Went from 17-18 to 21-22 mixed. If you let it get up to speed in auto mode, then go to manual and up shift. Simple to try and see if your mileage increases.
Then you will know if you need a trans calibration.
With the 35's mine does not like to use lower rpm on the motor. Always wants a lower gear then needed.
This is a great idea.
 
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Have you tried just using manual mode on the shifter? That's how I drive mine. Went from 17-18 to 21-22 mixed. If you let it get up to speed in auto mode, then go to manual and up shift. Simple to try and see if your mileage increases.
Then you will know if you need a trans calibration.
With the 35's mine does not like to use lower rpm on the motor. Always wants a lower gear then needed.
Excellent idea!

Yes, I noticed once the transmission gets to a higher gear, it tends to stay there.
 

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Have you tried just using manual mode on the shifter? That's how I drive mine. Went from 17-18 to 21-22 mixed. If you let it get up to speed in auto mode, then go to manual and up shift. Simple to try and see if your mileage increases.
Then you will know if you need a trans calibration.
With the 35's mine does not like to use lower rpm on the motor. Always wants a lower gear then needed.
That's actually a pretty slick idea. I used to throw the tranny into 8th sometimes since it was so picky about getting there on it's own. (We no longer have this Jeep)
Side note: He has the V6 and that engine likes to have it's RPMs up, that's where it performs the best.
 
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On second thought, because the terrain here is pretty hilly, the few times the transmission got into 8th gear, it downshifted down to 7th as soon as it encountered the slightest incline.

Still, I think this solution should work great for those in flatter states.
 

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This is unlikely, but I'll share it anyway. I once had some failed O2 sensors that were triggering the anti-lock brakes without me knowing it. MPGs dropped like a rock, and it always felt like I was driving into a headwind. I went to four garages who couldn't fix it but always found something else to bill me for. Luckily I found somebody who dealt with a similar issue. He replaced the sensors, and my MPGs went right back up. Again - its unlikely this is your problem, and as my doctor brother says "when you hear hooves, think horse not zebra," but file the idea away if nothing else works.
 

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Yeah, well, re-gearing is not an option for me. I am already having too many problems getting Jeep dealers to honor the factory warranty as it is, with only a dealer-installed Mopar lift.

Just getting a Jeep dealer to do the steering TSB this week took months of perseverance and dogged determination on my part. I am afraid re-gearing would be a bridge too far.

I have trust in Jeep powertrains, transmissions and transfer cases, but its electronics and electrical systems are a different story. If modern Wranglers were simpler and had fewer electronics, or even if I had a fair dealer, I’d re-gear and take my chances. But not with the spotty track record FCA and its dealers have.

At this point, if the only option left to regain some semblance of fuel economy is to go back to smaller tires, I might have to swallow my pride and do that.

Of course this would defeat the entire purpose of having gotten a Mopar lift in the first place. But apparently these are the realities in which Jeep owners are being forced to operate these days.
I'm probably the only person who thinks this, but I thought your Jeep looked better before your lift and tires. Those KO2's looked proportional to the vehicle. 35's on Sports and Saharas just look too stuffed into the smaller wheel flares, IMO. Those white rims are awesome, though.

I think I read elsewhere that you were unhappy with how your Jeep drives after the lift? Perhaps ditching that and going to Rubicon springs or a spacer lift could get you a nice 1" lift, and then put some 33's on those retro wheels.

Then you would have a nice visually balanced vehicle that drives well and gets decent gas mileage. Just the opinion of someone who wants to go that route for my wife's Sahara.
 
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BTW, I got the Mopar lift installed last December; the 35s last January.

So these MPG numbers may have already existed last winter. But because we were all holed up in lockdown and social distancing, and may not have noticed it.
 

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I'm probably the only person who thinks this, but I thought your Jeep looked better before your lift and tires. Those KO2's looked proportional to the vehicle. 35's on Sports and Saharas just look too stuffed into the smaller wheel flares, IMO. Those white rims are awesome, though.

I think I read elsewhere that you were unhappy with how your Jeep drives after the lift? Perhaps ditching that and going to Rubicon springs or a spacer lift could get you a nice 1" lift, and then put some 33's on those retro wheels.

Then you would have a nice visually balanced vehicle that drives well and gets decent gas mileage. Just the opinion of someone who wants to go that route for my wife's Sahara.
@ODDs - Hey Aldo, I know you've been frustrated with your Jeep. Can I please kick you in the nuts too?
@aldo98229 - WTH might as well.
 
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I'm probably the only person who thinks this, but I thought your Jeep looked better before your lift and tires. Those KO2's looked proportional to the vehicle. 35's on Sports and Saharas just look too stuffed into the smaller wheel flares, IMO. Those white rims are awesome, though.

I think I read elsewhere that you were unhappy with how your Jeep drives after the lift? Perhaps ditching that and going to Rubicon springs or a spacer lift could get you a nice 1" lift, and then put some 33's on those retro wheels.

Then you would have a nice visually balanced vehicle that drives well and gets decent gas mileage. Just the opinion of someone who wants to go that route for my wife's Sahara.
You are not the only one who thinks the Jeep looked better with the factory rims and 33-inch KO2s; I do too.

I love the Mopar lift: I love the ride and what I can do on the trails. I was, however, having issues with the steering after the lift and once I got the 35s. Thankfully, most of that was rectified with a Fox 2.0 stabilizer and the steering box TSB.

I still have the stock Sahara rims in the garage. I am very tempted to dust off those rims, downsize back to a 33-34 inch tire, sell the 35s and the retro wheels —as much as I love then, and be done.

I wouldn’t get rid of the Mopar lift. But I think the Jeep will look goofy with the Mopar lift and 33-34 inch tires.

This is how she looked right after she got the Mopar lift, still with the 33-inch KO2s. The suspension has settled down a little since, plus I added a winch to the front. So it might not be too bad.
Jeep Wrangler JL Unhappy with MPG - looking for ideas 3E24ADB9-D9C4-4A1D-88DF-7067DEBA5237
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