does fuel pressure affect gas mileage at all AFTER its tuned?

 

fuel pressure aside, if your car is tuned to stoich in the low rpm and low load areas of the map, thats the best MPG you're gonna get.

 

yes.
more fuel pressure = more fuel pushed in when the injector is open.
tuning sets the injector timing so the correct amount of fuel is injected. Mess with the pressure you mess with the tune.

it may sound like a good idea to mess with it, better MPG with less pressure, but it will run lean when at WOT. which will destroy things fast.

 

sounds like a bad tune.

 

or just a tune for power rather than MPG

POWER OR MPG... your choice or try to get a compromise between the 2

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by charliev &raquo;</TD></TR><TR><TD CLASS="quote">POWER OR MPG... your choice or try to get a compromise between the 2</TD></TR></TABLE>

No, that is a false choice (lesser of two evils). The point of tuning is to get the best mileage and horsepower, safely. Any good tuner can get that with a street and dyno tune.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mar778c &raquo;</TD></TR><TR><TD CLASS="quote">

No, that is a false choice (lesser of two evils). The point of tuning is to get the best mileage and horsepower, safely. Any good tuner can get that with a street and dyno tune.</TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bambam &raquo;</TD></TR><TR><TD CLASS="quote">

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AFR's should generally be around 14.7:1 at idle and in low load areas of your map w/ slight increases in fuel corresponding to load, all the way to a nice 13.0-13.2 AFR for WOT. You can lean the motor out a bit across the board to make a few more WHP, but you sacrifice some reliability and induce more heat into the motor.

 

so what AFR would you consider rich at WOT?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b20beast978 &raquo;</TD></TR><TR><TD CLASS="quote">so what AFR would you consider rich at WOT?</TD></TR></TABLE>
Well 13.0:1 is considered rich...
But, if you start tapping into the mid 12's....you're definitely running too rich. If this was a boosted motor, of course this would be different.

 

so at WOT, a reliable AFR should land around 12.8-13.5?

 

Anywhere around 13:1 to 13.3 is good. The additional fuel above 14.7 serves to cool the combustion chamber.

 

how about on cruising speeds..what should your AFR be at?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b20beast978 &raquo;</TD></TR><TR><TD CLASS="quote">how about on cruising speeds..what should your AFR be at? </TD></TR></TABLE>

14.0-14.7 range.

 

Wouldnt the ecu adjust injector pulse width once reading rich from o2 sensor.

More pressure more flow,so computer just closes injector sooner.

 

Well let me throw my .02 in now my ECU is a P06 chipped on an ITR all motor setup. A/F runs stoich at idle cruising is around is around 15.2-.9:1 and WOT is around 15.0:1. As far as my fuel pressure 60psi at idle and not sure at VTEC. My mpg is great 35mpg street driving. I definately have issues just dont know where to start?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by burnsmonkey &raquo;</TD></TR><TR><TD CLASS="quote">Well let me throw my .02 in now my ECU is a P06 chipped on an ITR all motor setup. A/F runs stoich at idle cruising is around is around 15.2-.9:1 and WOT is around 15.0:1. As far as my fuel pressure 60psi at idle and not sure at VTEC. My mpg is great 35mpg street driving. I definately have issues just dont know where to start?</TD></TR></TABLE>

that tune is kinda off or your wideband is nuts.

 

Well regardless my fuel pressure is whacked and i dont know why.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by burnsmonkey &raquo;</TD></TR><TR><TD CLASS="quote">Well let me throw my .02 in now my ECU is a P06 chipped on an ITR all motor setup. A/F runs stoich at idle cruising is around is around 15.2-.9:1 and WOT is around 15.0:1. As far as my fuel pressure 60psi at idle and not sure at VTEC. My mpg is great 35mpg street driving. I definately have issues just dont know where to start?</TD></TR></TABLE>

Larger injectors, less fuel pressure. Then retune.

 

Runnin 310cc injectors gonna lower the pressure today. ill report back.

 

Well tried to lower the pressure but when i did it leaned out like crazy, so i had to raise back to the right point and its runnin great a/f but still 60psi fuel pressure.

 

Sounds like a horrible map. Ditch the EBAY chip and get a real tune.

 

Well i didnt want to say who chipped it since it is a reputable shop in FL. Im gonna try my buddies Mugen chip and see if there is a difference.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by burnsmonkey &raquo;</TD></TR><TR><TD CLASS="quote">Well i didnt want to say who chipped it since it is a reputable shop in FL. Im gonna try my buddies Mugen chip and see if there is a difference.</TD></TR></TABLE>



Are you seriously that thick? Until you have the motor on a dyno, tuned for your particular setup, DONT be complaining about poor mileage or anything else. I dont care how "reputable" a shop is, there is no "magic one-size-fits-all" chip. Get real.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Combustion Contraption &raquo;</TD></TR><TR><TD CLASS="quote">



Are you seriously that thick? Until you have the motor on a dyno, tuned for your particular setup, DONT be complaining about poor mileage or anything else. I dont care how "reputable" a shop is, there is no "magic one-size-fits-all" chip. Get real.</TD></TR></TABLE>
Again if you read what i said, im not getting poor gas mileage, im getting great gas mileage. I know that it needs a dyno tune but regardless there is no reason why it should be high fuel pressure even with a stock ecu. Again I haven't complained about anything but the worry of my motor suffering of high fuel pressure.