PMCR and Mileage

[Georgia Cracker]

On a 80 mile expressway run, I set my PowermaxCR on 1 (Power) and Torque on 0 for the best mileage. I started showing about 1 mpg better on the computer.



Then I reset the computer and set the PMCR on 4 for power and torque and mileage improved about 2. 5 mpg. I have an AFE and stock exhaust



I had noted this paradox before but didnt have an opportunity to check systematically. Just wondered if anyone else has had a similar experience.

 

[ThomasLawrence]

Any of the fuel-delivery-enhancement boxes are going to skew the overhead display, because the stock computer doesn't know about the extra fuel being delivered.



When you're running a fueling box, forget the overhead display - reset your trip odometer at every fill-up, and do the math to calculate your fuel economy.



My overhead reads 20. 4MPG right now. By manual calculation, I'm around 17. 1MPG. I'll still take it



-Tom

 

[Georgia Cracker]

The numbers are unreliable if you are using the overhead cumulatively. You are not successfully isolating any dependent variables for comparison.



If you reset the computer and drive 10 miles at 65 MPH on an expressway with the PMCR set at 1/0, it will provide you with a set of dependent variables for comparison. The MPG numbers for those parameters are isolated.



If you reset the computer and the PMCR to 4/4 and drive another 10 miles at 65 MPH, you are comparing the effect of those variables on your independent measure. You have values that are comparable and provides some useful discriminations.



10 miles at 65 MPH with the PMCR set on 1/0 = 16. 3 MPG.



Then, 10 miles at 65 MPH with the PMCR set on 4/4 = 17. 8 MPG.



This is counterintuitive and contradictory. Just wondered if anyone else experienced the phenomenon.



The advanced timing and additional fuel may be creating a more efficient driving combination.

 

[timjones]

Nice theory, but in reality the over head display is calculated by the computer you are fooling so you have garbage in/ garbage out. As you increase the fooling, the off set is a increasing fooled display, so if you were to take your testing and got to 9/9, your overhead would be 39. 2 mpg. that is assuming the fooling is linear. the display is taking what the computer believes to be the amount of fuel delivered times the speed to calculate the displayed MPG. What all this means is put on a box an you have GIGO. (garbage in/ garbage out) and forget the display.

 

[Georgia Cracker]

My answer and yours represent a good example of why we should be suspicious of experiments and conclusions. Establishing cause and effect relationships is not easy even if you are trying to be systematic. I hate to go back to calculating my mileage by hand, but thats the price you pay.



Thanks for providing me with the right answer.

 

[lmills]

I actually found my overhead display to be more accurate with the TST box on . When running stock it was reading about 1-1. 5 miles better than I was getting on paper. With the box on it was reading within about . 2 of my calculations on paper. With the pressure boxes I tested in the past, the numbers were way off. Some of them read 5-6 miles better than I was actually getting.

 

[JPalese]

Calculated Mileage?

Originally posted by Georgia Cracker

My answer and yours represent a good example of why we should be suspicious of experiments and conclusions. Establishing cause and effect relationships is not easy even if you are trying to be systematic. I hate to go back to calculating my mileage by hand, but thats the price you pay.



Thanks for providing me with the right answer.

Georgia Cracker:



Please let us know what the hand calculated mileage works out ot be.