Hey guys,

just purchased and installed the bullydog gtx tuner on my 15 6.7 powerstroke. I have the performance tune running on it now. I've not driven it much yet just a 20 miles but I have noticed that the mpg real time display on the dash is significantly less then with a stock tune ( even with driving like there is an egg under the exellerator) wondering if anyone has experience with this tuner. I'm wondering if with the new tune if the truck can't calculate mpg the same. Taking a trip over the weekend and will do the actual mpg calculation.

 

my experience has been the AFR for power and the AFR for economy will not be the same

 

In other words your thinking that the milage that the truck is calculating might be correct? Maybe I should look into getting an economy tune. It would be nice to gain a couple mpg when not towing.

 

 

Thanks Dave you are so smart

 

So, you don't understand why the Performance Tune (hot rod, power) is giving you less MPG than the Stock Tune (Grandma driving)? I believe that is the trade off. Djosbun asked a legitimate question. Yes, the Stock Tune will increase MPG.

 

Maybe i didn't explain the question i was asking properly. The question i was asking is when i hooked up the tuner to the truck if the electronic fuel consumption app that is built into the truck would be correct Or would tuner affected the trucks ability to calculate fuel mileage. I understand that there will be more fuel consumption if i set the truck on the high performance tune. also this tuner came with 0 instructions on the tunes i was also looking to see if anyone else had experience with this tuner.

Its almost a year later have been using the tuner without any issues. Running the truck on the street tune now mileage isn't great on short runs and when pulling but on the highway driving reasonable 16mpg.

 

Some guys here say that their displayed MPG and their hand calculated mpgs are very close. I would do it by hand to see how yours compares with the hand calculated mpg.

Since you are running a performance tune, it takes more fuel to produce more power, even if you are driving conservatively. The extra fuel is still there. As for the tuner affecting how the ECM calculates mpg, it doesn't. It's just lower because the tune is calling for more fuel. The tune just affects the fuel mapping tables and other things I'm sure. But I would assume the ECM does what it needs to do to calculate your miles per gallon as it did before.