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Discussion Starter · #1 ·
2007 Sahara with about 120k miles on it. I've noticed over the last year that my mileage is way down. About a year ago I added 35s and a 2.5" lift. Around that time, but even before that, I noticed that some days the Jeep was just struggling to maintain speed. I brought it into the shop I trust and asked them to give it a full once over, I didn't care how long it took, just check everything. It had been doing a funky abrupt jump out of first into neutral 1 out of every 10-15 launches, it was idling rough at times too, etc.

During this time, I would notice days where the Jeep just couldn't maintain 65 in 6th when dealing with slight inclines (think minor elevations when on a freeway elevates to go over underpasses) and the milage reported was near 14-15mpg at 65-70. Other days it ran fine, I could even accelerate on those same inclines in 6th and was seeing reported ~22 mpg at 65-70

They found the wiring harness for the spark plugs were basically dying if old age. That was causing arcing across a couple of the plugs internally in the harness; causing misfires etc. But it only presented itself in extremly hot days or conditions.

Things were much better after that change. Pretty consistent feeling of the expected power. After the adding of the tires, aftermarket bumpers, and lift, it still was very similar but now ~20mpg reported. Well, in the last few months it's back to pretty consistently 15mpg at 65-70 and struggling to maintain speed in 6th. On bad days it's 5th to stay at 70 without inclines, 4th to stay at 65 on a bridge.

What should I start looking at? I run 89 octane fuel. I'm making sure I have proper oil levels and change it every 5k (high milage mobile 1 synthetic). I checked and there aren't any active codes in the computer either.

I appreciate the help to anyone who tries with advice.
 

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On an off chance if truly everything motor related is good. May want to check for a dragging caliper. Easy check is drive for a while and use a temp gun like a raytec or equilavent to check and make sure each side of the axles are relatively close in temperature. Front will be hotter then the rears. 20-30degree variance is ok side to side. but if there is a huge temp difference you know you have one dragging. Next step is to figure out why.
 

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Discussion Starter · #3 ·
Thanks for the idea. This may be the issue. I'm going to change out the rotors and calipers next weekend with a new set of Powerstop Z36 Truck and Tow. Early last week I noticed hearing what sounded like dragging/grinding on the passenger rear the moment I barely touched the breaks. There is some grinding going on during stopping on that one brake and the rotor is showing wear when the others aren't.

I figured they were just end of life as these breaks are around 50k miles on them with original rotors.

I'll report back after I change them out and I see if the problem still persists.
 

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Discussion Starter · #6 ·
Houston.

I thought fuel as well but on the road trip that it was the worst I dropped injector cleaner and ran a full tank of premium just to see, and it was still awful, until today.

The more I think about it, the worse it has been was 3 Sundays ago when I took a road trip to Louisiana. Upon returning, I noticing that rear brake grinding for the first time and it continued at times even after letting off the brake and accelerating. I could hear some rubbing at first. I'm really beginning to think it's that rear passenger caliper

Today when doing the drive to work I feather tapped the break a few times after each time I let off the brake and was starting my acceleration. Jeep got near 18mpg for the hour long 50 like commute that included some surface streets. That rotor also looks worn worse than it did just 15 days ago while there others all look great.

I'll know by Saturday when I get the rotors off and I can compare them side by side.
 

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I just posted about our 2014. Sounds the same as far as acceleration, but no noises.
It struggles to get over 3rd gear, then uphill wouldn't maintain speed, ZERO acceleration to pass. I really thought the engine would start going in the desert heat due to the high RPM's to get into a higher gear.
No one at the dealership seems to know what it is, now I think they're just randomly guessing....
Has yours been corrected? The fix? I'm thinking this one needs a new tranny and they are just stalling?
 

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I just posted about our 2014. Sounds the same as far as acceleration, but no noises.
It struggles to get over 3rd gear, then uphill wouldn't maintain speed, ZERO acceleration to pass. I really thought the engine would start going in the desert heat due to the high RPM's to get into a higher gear.
No one at the dealership seems to know what it is, now I think they're just randomly guessing....
Has yours been corrected? The fix? I'm thinking this one needs a new tranny and they are just stalling?
Hi Seminole1212,

Is your Jeep currently at the dealership? Please send us a private message with your VIN if it is, and we can have a case opened so a specialist can reach out to your dealership.

Kori
Jeep Social Care Specialist
 

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I thought fuel as well but on the road trip that it was the worst I dropped injector cleaner and ran a full tank of premium just to see, ...
Reminder to folks out there. Premium and Regular mean nothing to each other!

Putting "Premium" into your vehicle that was built to run on 89 octane is a bad move. The timing and stroke of the pistons is designed for the fuel and air mixture to detonate at a certain point in relation to TDC (top dead center).

Repeat: DO NOT put in "premium" fuel to the vehicle just because you think it is better. It is not. It is simply a higher octane which will combust at a higher pressure. Not meant for most standard engines on the streets today.

(My car with a turbo on the engine does require 92 octane though to prevent early detonation and possible damage)
 
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