I just received the Procal and loaded up my computer with all the correct data. I was showing 16 mpg before, now it's showing 20mpg. If that's true, that's about 110 miles extra per tank of gas.

History: I bought my 2013 JKU Sport with 3.21 gearing in January with the stock 29's on it. I had them change out the tires for the bigger stock 32's. I don't think they changed the speedometer, when I went through school zones with the radar signs I was always showing 5-10 mph faster on the sign than what my speedometer said. And I wasn't getting the good mileage the 3.21 is suppose to get. The actual size of the 32's is 30.75" as entered into the Procal.

I had read somewhere that most dealships won't adjust anything in the computer as long as it's under manufacturers warranty. (I don't know if that's true or not.)

 

I think you answered your own question! The difference is now your speedometer is set to acurately portray your speed based on the true tire size you're running. You're gas mileage didn't increase, the computer is just doing a better job at calculating it now that your speedometer is correct!

 

Exactly! The way I understand it, if you have an automatic, the shift points will be adjusted better. That could possibly help a little with MPG, but mostly with accurate shifting. Other than that, it is simply getting your gauges to show correct data.

 

yes remember not only is/was the speed off but the tripometer is/was off too.

 

Exactly. And don't just go by the tire's advertised size- measure your tires on the ground (with the Jeep weighing them down) and get the actual height if you want speedometer/odometer/MPG to be accurate. It could also affect gear shifting if you are in an automatic.

Oh.. with better reading comprehension I see that you did measure the tire. Carry on.

 

Procal doesn't adjust shift points.

A true tuner is what is required to adjust shift points.

 

If your actual size is 32.02 - should u set the size to 32.00?

 

You should ideally only have to set it to what your tire actually measure by you, however in some cases even after doing so it is still recommended to double check the setting by using a GPS.

I believe I had to set my compute rto .5" difference of what I measured my tires to be, in order for it to display the correct reading.

 

yes that is correct

 

I live a couple of miles from AEV and Dave Harrington's brother invented the procal and he told me that it does in fact adjust the shift points to where they are supposed to be. If you are saying that you can not adjust them to where you want them you are correct but the Procal does adjust the shift points back to where they are supposed to be when adding larger tires.