a custom tune is essentially when you are on throttle in boost, and the ecu is in open loop control

Cruising and out of boost, the ECU is in closed loop control, to this date, how to alter the closed loop control is a bit of a mystery

However, to the OP, what did you expect? The MR is listed at 24mpg..what are you getting?

Im mostly city and avg about 17mpg

 

How do I find out my MPG? What method are you guys using? I fill up like every 2 days, 3 if im lucky. My job is approximately 16 miles away from home. After work I might put on an extra 5-10.

 

I just divide my miles driven by the amount I have to fill up...that'll give you a close estimate to what you're getting per tank.

 

Like on Monday, I filled up 14.1 gallons and was at 310 before I reset...thats driving relatively easy while boosting a few times.

 

If you lean out your fuel curve (be careful!), get a high flow intake and exhaust, your mileage will be way better than stock.

 

you calculate MPG this way:

1) fill up till it stops by itself; do not overfill as this will mess up how much gas in ur tank u used up.
2) set ur trip A/ trip B to 0 miles right after u fill up.
3) drive until u have to get gas again.
4) fill up till it stops by itself without overfilling. write down how many gallons of gas u've just put into ur tank.
5) divide the miles u got for this tank since last fill up by the amount of gas u've just put into ur car.

for example: trip A = 270 miles. u've just filled up 11.23 gallons...270/11.23 = MPG.

hope i didnt miss anything.

fwiw my stock IX gets 21-22 MPG 40% highway 60% city. after i got my Works filter the MPG went up to 22-23. after i got just my catback it went back down to 21-22 again. but then again it's getter colder here in socal, so that could affect my MPG as well.

also lookin for a custom tune for improved off boost MPG and power on boost as well

 

Well, you'd just need to connect your exhaust to your intake. Why you'd want to, I have no idea since cars burn fuel extremely efficiently and you have no way to separate the unburnt fuel (if any) to be routed to the fuel injectors from the oxygen to be routed to the air intake.

On a more serious note, if you're calculating MPG based on fill-ups, it's best to use the exact same pump every time.

 

You guys that are saying to add an intake or exahust to get better mileage are incorrect. Both of those modifcations increase airflow into the engine, increased airflow requires an increase in fuel. If you are burning more fuel per power stroke you are getting worse mileage.

 

That would be perfectly true if we were at wide open throttle 100% of the time. However decreasing back pressure theoretically increases the efficiency of the motor.

So... in less fuel consuming situations like partial throttle and non boost I could see it making a positive increase.

 

dam i was excited i was getting 16-17

 

When your car is driving at speed without changing throttle position the ECU is in cruise mode. Cruise mode is already tuned for minimum pollution and gas savings. the ECU is tuned by every car manufacturer to run very close to 14.7 afr in cruise mode. This setting gives the best pollution control and gas saving combination. To set the car leaner in cruise mode increases pollution.

you can effect your wot gas use with a flash tune, but to do so for gas economy is kind of silly. go easy on the gas pedal.

 

I understand that staying out of boost can improve the gas mileage. But, isn't there a way to improve gas mileage by keeping the boost/vacuum gauge's needle within a particular vacuum range? In short, can the vacuum gauge be a help in improving mileage? And if yes, then how so?

 

Not really anything to do with a particular vacuum range, but you do want to keep as steady of a foot as possible. Gradual acceleration helps. You'll be driving like a Grandma. Keep the rpms relatively low too. I'd say aim for 2500 during steady driving in cool weather and maybe a bit higher in warm weather where the engine is a bit less responsive.

 

Adding an intake or exhaust gives you better gas mileage. This is not a rumor or heresay, it is a tested scientific fact. The engine has to do LESS work to produce the SAME amount of power.