EVL JEEP

Ok checked axle ratio using that method and driveshaft turned a little smidge over about 4 and 3/4 so I'm guessing that's going to be 4.88 gears I think. Is there any other gear sets that it might be? My guess is previous owner reprogrammed it with a programmer and put in 35" even though they don't measure true 35". If the jeep has a modified program that was left on it and say I buy a flashcal, can I fix the tire size and axle ratio?

nthinuf

4.10, 4.56, 4.88, 5.13, 5.38. From your findings, guessing 4.88 seems reasonable.

AEV tech support told me that a new Procal will over-write my lost Procal. I don't know if a new flashcal or tuner will over-write an old one, but I suspect that it will. If it does not, you might need the dealership to flash it back to stock settings first.

Another note on that is that the unit used to program your JK is still locked to your JK. It can not be used on another vehicle until they pay that company to have it unlocked. So might be worth trying to track them down.

EVL JEEP

I wish I could track down the owner that did the work, but unfortunately it went through several dealerships hands bc they didn't sell it and another dealership bought the jeep thinking they could sell... Which they did to me. I think I may try the procal if that doesn't work then on to jeep dealership. Thanks for your help and insight guys.

jadmt

You want to rotate the tire 10 x and count ds rotations and divide total ds rotations by 10 for an accurate reading. Again if the incorrect gear ratio is programmed you will not be driving as it will go into limp mode. Also I still think op either reset back to stock and took programmer with him when he traded. Your speedo is off about what I would suspect going from stock tires to common sized 35's. Being its used I'd change diff fluids just because and count the gear teeth.

maxspongebob

I don't get it. Op said that he counted the rotations and the DS was just over 4 3/4. Sounds like 4.88's to me.

You need to get a programmer and flash the thing with a new tire size. Just make sure that the one you use is able to program tire size and gear ratio at a minimum. As far as I know, the programmers will not tell you what the current gear ratio and tire size is programmed to by reading the car. They can all overwrite the data that is there though. Also the car is not locked to a programmer, the programmer is locked to the car. So it makes no difference what it was originally programmed with.

Whatever the case, you need to set it to a known value, preferably something close to the correct value. Then make an adjustment from there to correct the difference in speed from the displayed value and the actual value. Yes, the Superchips Flashcal is an excelent choice. Just make sure it is one that works with your year Jeep.

EVL JEEP

Update: got the programmer and updated the axle ratio to 4.88 and decided to put 33" tire as they were 35" to begin with but are wore out, they actually measure 34 or little under. Took it for a drive and according to the speedo says 60mph but with GPS (accurate within 9ft) says 56mph. I would guess that by putting in a slightly smaller tire the speedo would be off but in other direction. Also I rotated one of the back tires 10 times and counted the driveshaft rotations but only counted 24 then he said to divide by ten so don't know what happened with that method but it didn't work.

EVL JEEP

OK so instead of actually programming the tire size to 33 I must've hit the exit button.... All is now good 😆