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Discussion Starter #1
Love Love LOVE my 08 JK. It's my first Jeep. Why didn't someone tell me how much fun these are to drive?!

But not on the interstate. Here in the great state of Texas you can drive 75 mph (legally!) but my beloved beast sure takes a lot of coaxing to get to 75. And it doesn't want to stay there on cruise. Lots of shifting up, straining, and then finally down shifting. Take it off cruise and I have to really put my foot in the throttle to keep her at 75 too. She doesn't seem to have much power.

On top of that when I go 75 my gas mileage absolutely collapses. 11 mpg!

Let's talk about how to improve and help this situation. Have seen these Superchips Jeep Flashpaq F5 Programmer that let you "tweak" it - like shift points. Is that a help or hype? Other ideas?

Thanks for your help. I gotta get this Jeep moving or in Dallas I'm going to get run over!
 

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Discussion Starter #4
What lift, tires and gears? Or are you all stock?

Sent from somewhere in Missouri
this is what happens when you post while watching football - you forget important details.

I bought it lifted but I think it's a 3" lift and I have 32s on it. gears? don't know but I'd guess stock. the guy who sold it to me would've said if he'd done something to the gears I think.

how do you measure lift? I have measured tires and iirc they are 32.
 

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Step 1: sell the '08 and get a '12 or newer. The 3.8 has less than 200hp. The newer Jeeps have almost 300hp.

Step 2: if you won't sell it, re-gear it.

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Discussion Starter #6
Step 1: sell the '08 and get a '12 or newer. The 3.8 has less than 200hp. The newer Jeeps have almost 300hp.

Step 2: if you won't sell it, re-gear it.

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can't sell it. love it. have a lot of $ in it.

don't know about re-gearing. that sound pricey. any other options?
 

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can't sell it. love it. have a lot of $ in it.



don't know about re-gearing. that sound pricey. any other options?

Put a pedal commander on it or a HikeIt. They will improve the throttle response. No HP gain, but makes driving it better. Put it this way, if I had to drive mine without my HikeIt I would sell the Jeep.
 

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I put 312,000KLM on my 08 and loved every minute of it, even on 37” tires. The engine isn’t the problem, the gearing and 4spd auto are.
To the OP go ahead get that SuperChips and consider regearing..
you will likely need 4.88 gears to get the best performance.


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this is what happens when you post while watching football - you forget important details.

I bought it lifted but I think it's a 3" lift and I have 32s on it. gears? don't know but I'd guess stock. the guy who sold it to me would've said if he'd done something to the gears I think.

how do you measure lift? I have measured tires and iirc they are 32.


What size is written on the side of the tire? Should look like... 285/75r17, 315/70r17 maybe 265/xxR17
 

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https://fcacommunity.force.com/RAM/s/equipment-listing

Put your VIN into the spot in the link. That will tell you want ratio is came from the factory at least. Base gear ratio was 3.21 with 3.73 included with Trailer Tow Group or 4-speed automatic transmission.

Auto or Manual?

Have you utilized a GPS app to check if dashboard MPH is had been calibrated for true MPH, if needed.
 

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I have a 2010 auto with 3.5” lift, and 35’s plus a ton of extra weight in mods that I bought stock - so same engine and transmission as you - and also live in Dallas so understand the highway comment. I’ve done all of the following in stages: 1) RIPP intake/exhaust 2) reprogram ECU 3) RIPP headers 4) regear to 4.88 5) Magnuson supercharger. 2012+ vs 07-11 Yes, we have a horsepower deficit that’s just silly. No, you won’t ever accelerate like they do without spending serious dollars but your Jeep can be made to at least be safe getting on our highways. Regear, regear, regear. IIRC I paid $1,500 for mine. Worth it if you’ve got it but gas mileage really won’t be you’re friend driving over 70 mph no matter what with this engine and transmission. If no regear, it’s all about planning your merge in advance... if you have the money and time, then of course the SC etc will help immensely but it’s not for everyone and sadly the crappy transmission will still be with you! Oh, if you have hardtop, I notice that top off helps too due to reduced weight. No doors even more... good luck!
 

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First step is to regear. Once you get the gearing right, the 3.8 engine is fine. In the rpm ranges where most people drive (less than 4000 rpm), there isn't a lot of difference in the 3.6 and 3.8L horsepower. The difference is in the gearing. For an auto, with 32 tires 4.88 gears. For a manual, 4.1 or 4.56 gears.

Also, remember that you are driving a brick. There is nothing aerodynamic about a Jeep, so wind can be a killer.

My 2010 is a manual with 3 inches of lift, 35 inch tires, and 4.56 gears. It ran fine like that, but with a headwind had a hard time keeping up in the 80 mph speed limit zones.

I have since added a RIPP SC, which solved that issue
 

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Discussion Starter #14
First step is to regear. Once you get the gearing right, the 3.8 engine is fine. In the rpm ranges where most people drive (less than 4000 rpm), there isn't a lot of difference in the 3.6 and 3.8L horsepower. The difference is in the gearing. For an auto, with 32 tires 4.88 gears. For a manual, 4.1 or 4.56 gears.

Also, remember that you are driving a brick. There is nothing aerodynamic about a Jeep, so wind can be a killer.

My 2010 is a manual with 3 inches of lift, 35 inch tires, and 4.56 gears. It ran fine like that, but with a headwind had a hard time keeping up in the 80 mph speed limit zones.

I have since added a RIPP SC, which solved that issue
so everyone wants me to regear. can someone ballpark me what a shop ought to charge to do that?

also what is RIPP SC?
 

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If you can't afford to regear, drive in the right lane and put your 4 ways on.....sounds like a gearing issue, and like was already stated - mpg will be crap at that speed.

I have the devil 3.21 gears on my '14 with 285/70-17s, and it will cruise at 80 no problem - but mileage takes a little dump. There is a huge difference in not only the 3.8 vs the 3.6, but the auto trans as well...that is if you have an auto. While the 3.8 is not horrible, it does not compare to the 3.6 especially on the highway.
 
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