well i filled my car up with 93 for my tune and ran that for a bit.i noticed that my mpg was droping very fast(16mpg) so i tuned it to 87,with no help with my mpg.mind all of us that i was getting about 18 mpg before the tune and intake. I filled up today with 87 and to my surprise get what my mpg in the city is now?? 20mpg!!!!!in the city!!!!! is that crazy or what. could it be that the 93 octane was burn hotter causeing me to get such a low mpg?? anyway just wanted to share this with you guys.

 

I had a Predator with the canned tunes in my car, and was running the 87 octane tune.

Before the tune, with the cruise set at 60, I was able to get ~27-28 MPG. After the tune, at the same speed, I was at 25. Plus, I didn't like the "on/off switch" feel that the throttle had. So, I ebayed it.

Hope this info helps. I couldn't believe that it dropped 10%. And no, it wasn't because I put my foot into it. I seriously set the cruise for 60 mile trip at 60 mph and saw those results.

 

Keep ur foot off the GO pedal and you'll do better

I average 23.5mpg summer and 20.5mpg winter on a tank

 

It would make sense that the mpg would go down. Your taking in more air, so the computer has to be flashed to send more feul. I havent noticed any drop in mpg until i get over about 80 mph, I usally average 23 highway, and 17 city.

 

Yes, but theoretically you shouldn't need to use as much gas pedal to keep the car moving, hence better fuel economy.

Even worse, Diablosport advertises "Increased Fuel Economy". I have to disagree. And, the same thing happened on my 00 V6 with the tuner. But, on that car, I was more concerned about the power than the MPG. On the Gt's however, there is more than enough power in my opinion (not that I have a problem with more power, but not at the expense of 10% less fuel economy)

 

That's the thing,when i ran a 87 tune with 93 octane,i was getting s hitty gas mpg. When i filled the car up with 87 i was getting in the 20's on the street. why???

 

That kinda makes sense...with your car tuned for 87 it isn't burning the 93 octane fuel properly(higher octane fuel would have more timing added) so it wouldn't be as efficient.

 

Sorry but I'll have to respectfully disagree on that one..If your running 93 octane even with an 87 performance tune ? your Stang's knock sensors will adjust and increase timing whenever a higher octane fuel is being used otherwise your air/fuel mixture would end up running extremely rich due to the 93 fuel burning way too slow..

 

Maybe I drive my car harder. But doing mostly highway driving at 70-80mph to and from work. I averaged 15 before the brenspeed intake and tune, and 17.5 after.

 

I would think that the timing would only increase if you had the stock tune which allows it, but wouldn't a custom tune have the max timing programmed in and the knock sensors would only reduce timing if you had knock?? I know when I run my 87 tune and put higher octane fuel in I do occasionally smell extra fuel and see carbon on the exhaust but don't have that happen if I run the correct octane.

 

The custom 87 tune's max timing is never the less optimized for 87 octane fuel and not for 93 octane which is why the knock sensors add more timing if your running a higher octane fuel other than 87 otherwise as I previously mentioned ? your air/fuel ratio would end up as way too rich due to the 93 octane fuel taking way too long to burn..