Jeep Wrangler Forum banner

1 - 16 of 16 Posts

·
Registered
Joined
·
27 Posts
Discussion Starter #1
Not sure if I have a transmission problem or not. Seems like the engine RPM is high at highway speeds.

I have a 2012 Wrangler Unlimited Rubicon, 5 speed automatic with 4:10 rear end. If you own this model and year can you check the RPM at certain speeds.

Driving Speed Tach Reading
55 2000rpm
65 - 70 2500rpm right at end of green line on tach;
80 - 85 3000rpm this is what I'm concern most about

IF you own a 2012 Rubicon can you respond with what your tach reads out at these speeds?

In reading owner's manual this model has what they call a transmission limp mode which keeps the transmission in 2nd gear and allows you to drive to dealer without damaging the transmission. Plus a malfunction indicator light would be on. Since this hasn't happened to me, I think the above readings are probably right for a Jeep with a 4:10 rear end. But would like to make sure that other owners have same reading.

Thanks in advance.

Mark
 

·
Registered
Joined
·
111 Posts
Those look about right to me...gas mileage plummets once you get past 55
 

·
Registered
Joined
·
27 Posts
Discussion Starter #3
Thanks for replay on Tach readings.

Actually, when I took a road trip to Houston from New Orleans, probably averaged 80 mph and got 17.5 mpg. Not bad for the speed. I can get 20mpg if I keep it around 68mpg.
 

·
Registered
Joined
·
273 Posts
Sounds about right to me. I'm right around 2800-3000 at 80mph.
 

·
Registered
Joined
·
8,554 Posts
You have 4.10s in the front too.

I don't have my chart handy, but that sounds about right to me. Get bigger tires if you want lower RPMs. :D
 

·
Registered
Joined
·
27 Posts
Discussion Starter #8
One other question. When you in autostick does the gears change as follows: 1, 2, 3, 4, drive?
 

·
Registered
Joined
·
59 Posts
2500 RPM = 110KM/hr for us Canadians.
 

·
Premium Member
Joined
·
198 Posts
2700 rpm @ 70 mph
 

·
Registered
Joined
·
892 Posts
Totally normal with the auto and 4.10s. This is the reason the default gearing is 3.73 on Rubicon. Unless you are putting bigger tires on down the road it is the best fit and yields better mileage.
 

·
Registered
Joined
·
273 Posts
When you in autostick does the gears change as follows: 1, 2, 3, 4, drive?
Yes it does
 

·
Registered
Joined
·
694 Posts
Yep, your good. It's not a diesel engine. Remember best mileage can be found around 55-58 MPH, as soon as you pass that, mileage drops hard. I can get 20 mpg at 58 mph, but at 70 it's only 15. Guess what speed I drive? I live in SoCal where gas is $5.00 a gallon or more. I let people fly past me, I could care less.
 

·
Registered
Joined
·
25 Posts
I took a nice long ride this weekend and watched my fuel gauge drop the whole time. I like to drive around 75 but cut it back to 65. I got about 18mpg @ 75mph and closer to 20 when at 65. I have a 2012 JKUR auto 4.10.

Maybe I can justify the cost of new bigger tires by telling myself that I'll get better MPG?
 

·
Registered
Joined
·
970 Posts
Just to add to what's already been said: I did a round trip from Upland, CA to Havasu, AZ last weekend = 257mi ea way. On the way to Havasu (seem to get better mileage that direction no matter what I drive) taking it easy on the new motor I kept it between 60 and 75 and the computer said 19.6mpg. On the way back with bad head/side winds I varied between 65 and 80 (mostly 70) and got 17.5mpg.

Tach readings seem on target - JKUR, auto, 4.10's
 

·
Registered
Joined
·
27 Posts
Discussion Starter #16
Gas really $5.00 a gallon in Cal? I can only feel some of your pain. New Orleans, it is around $3.60.
 
1 - 16 of 16 Posts
Top