I have a 2012 Rubicon 2D automatic and will be running 35" MTR/kevlar tires i was told that 4.88's can send the ecu into limp mode and was told I should go with 4.56 anyone have any input?
Any gear change will likely confuse the computer if you do not correct it with a programmer. As long as you have a programmer that can adjust for it, a gear swap shouldn't be an issue.
I am running the Bullydog GT but was told the ECU can still sometimes go into limp mode I only want to re gear once and being stationed overseas don't have access to a dealership if the ECU gets messed up.
I am running 5.13's on a 2013 2 door automatic. I used the FlashCal to adjust tire size and gear rato. No limp mode.
However, I had also installed a Yukon grizzly auto locker at the same time - come to find out auto lockers create havok with the tranny in the 2012 and up JK's.
Removed the Grizzly and replaced it with the Eaton "E" Locker and all my issues went away.
if you have a manual its a non issue, but the autos can only use a selectable locker in the rear. The traction control is confused by the locking and unlocking of the auto locker when turning.