I had a local guy swap out my 3.12 (edit: 3.21) axle ratio for 4.10, but he couldn't do the computer adjustments, so I'm in limp mode. I live in the Flemington, NJ area. Anyone local care to make a buck doing this for me?
I did download the OBD JSCAN app and have ordered a module from Amazon that "should" be here on Sunday. The problem is we had planned to leave on vacation really early on Monday morning to avoid traffic and Murphy's law says that this is cutting it too close. With my average computer skill, I can probably get it done, but not fast enough to keep my wife happy. Any help would be appreciated.

 

Might call around to any tuning shops in the area that use HP Tuners. They don't have to credit the vehicle to make this change - it's done in the scanner. I would do it for next to nothing if you were close.

BTW, your stock ratio should have been a 3.23. Never heard of a 3.12.

 

Thanks for the suggestion. I'll check around, but if there is someone local, I'm still interested.

Damn! We're both wrong. It was suppose to be 3.21.

 

Hi AnOLDUR.. I believe you will need to purchase a license from JScan for 1 vehicle VIN #.. With a Bluetooth Donegal and your smart phone you should be good to READ codes & change the settings in the Body computer to 4.10. Before get to the JScan website for some tutorials. We use it on 2 JKUs with an Iphone. So far works fine.. changed TPM system to 28 psi (we run 35s) .. both are 6 speeds I am suspecting that the 4.10s did not cause the limp-in.. so be sure to check for codes. IF you could get to one of the chain auto parts stores they can check for codes.. get the code and get on the Net for research.
ALSO.. check here for a local club, and their site for members .. https://clubs.jeepforum.com/State/New_Jersey/

 

It sounds like the dongle will be there Sunday. You should be fine. Once you have a BT dongle it's pretty straightforward. Buy 1 license, plug dongle in, it's intuitive. Adjust gearing and tire size.

 

Found a video on using the app and module and it looks pretty straight forward. If it weren't so close with our scheduled plans, I wouldn't be worried. In fact, it sounds like an interesting challenge. Regardless, it looks like I'm at the mercy of Amazon delivery. Thanks for the info on local clubs. I hadn't thought of that and will be checking it out.

 

Murphy Law broken. The worst of what could have gone wrong, didn't go wrong. Amazon pulled through and (although intimidating) the module and app got the job done. No more limp mode, shifts smoothly and RPM's at 70mph match up with chart for 4.10 gearing. Thanks to everyone who replied here.

 

Have a safe trip!

 

The Story has a Good Ending... Be safe enjoy your trip..AND.. thanks for updating on the progress.

 

Thanks! And to add to the update, made it from NJ to Nashville. Lots of long climbs on 81. The 4.10 gearing pulled our 2000lb trailer so much better than our experience with the 3.21.


We made it. Happy wife / happy life!