Tuning for fuel milage? Options

[AWD DSM 1]

Shamou got a little less than 20 on her first tankful.... hoping that goes up. Might be worth throwing the SAFC on just for kicks.

[NOMIEZVR4]

The reason why I want to raise the pressure is because my stock injectors at 10lbs of boost are seeing close to 90% duty cycle. Im sure when I raise the boost, install the exhaust and cams I will need extra fuel.. 

So, raising the fuel pressure will have no adverse effects on gas mileage?

No it won't. Closed loop can make up for that. I would recommend hacking the MAF one small bit at a time to make sure you don't take out to much. Log her between changes to see what happends. It may be enough just to take out the lower comb and then play with the adjustment screw in the bottom.

I know stock these cars run on the rich side, so hacking the MAS should lean out the a/f ratio. Though my question to you is this, what exactly should I be looking for on the logger? Knock will be the #1 priority as always, but there is no accurate way of seeing if the car is running better or not without a wideband.

What do you think?

[ncgalant]

After hacking the MAF properly your fuel trims should be close to their normal levels. If I had the guess they would end up at 125lo 110mid 100hi. This is commonly what happends when you hack a maf because at low air volume, such as idle, most of the air goes through the hacked section, but from cruise to WOT the flow evens back out. This is why you hack to get the high trim between 100 and 110.

[Kazz5]

BTW, unexplained crappy fuel mileage can often be attributed to bad O2 sensors, also. Have 'em checked out if your mileage is down!

[SCCA Stang]

I've found that all the modifications and tuning I've done to my car has actually increased the mpg. When I first got the car it got 19, now even with bigger injectors, bigger pump, bigger everything the milage has gone up to 25-26. Faster and more mpg, got to love that!

I have seen the same results and even damn near identical numbers to what you said above... although... I wonder if the mods simply replaced some much needed maintenence items that had I just replaced with OEM would have improved mileage as well or more.

The other thing is the theory that a HP engine works more efficiently because it doesn't have to work so hard to get out of it's own way. thus it might get better mileage on it's own as long as it isn't under a large load like racing.