CataclysmGT

My info center is typically off by over 1 gallon at every fill up. lately, mileage has been worse since I have been using Brenspeed of VMP tune, and the error is even greater by at least 20%.
So here's the real question, is my car running richer then 14.6 A/F when the car is in closed loop fuel injection? Because if the metered amount is less then actual, then one could assume that the A/F is off by the same % error, no?

Previous mileage used to be about 24.5mpg highway. With the tune(s) I get about 22.3mpg

howarmat

mine typically says 0 miles when i have 1 gallon left

ChiDiddy

a/f is always around 14.7 during closed loop.

just dont trust the fuel consumption computer with your life. it only calculates MPG based different inputs like throttle position, speed, etc, does not measure actual fuel usage coming out of the injectors.

sawyer

Is it the computer in the car or the gas pump computer......who has more to gain

owero01

I think its by design so you will fill up before completely running out.

CataclysmGT

Its just that others fuel consumption computers are accurate. Since it is EFI, for a given MAF signal, the computer should be adding an exact amount of fuel per injector stroke. Meaning, if it adds it all up, the volume should be correct. Now, does the computer add the actual flow rate of the injectors, or is it an estimate based on other factors?
If it is an actual summation of injector pulses etc, then my car would be running rich even if it runs at 14.7 A/F, because it is adding more fuel then it thinks it is. And its for sure not a "safety" thing, because the computer would read HIGHER fuel usage to say you are empty before you are. My "miles left" reads much greater then is possible with my actual fuel consumption.

Why does my car get worse mileage now? Most people indicate an improvement after getting a CAI and tune, where as mine has dropped 10% at least.

Nuke

[sm=exactly.gif]

howarmat

Some people get more MPG, but every car is different and you are probably getting into it more often also, so then MPG would actually go down

sd07gt

When mine goes to zero I still have 1 1/2 gallons left !

PiggySmallz

i lost 2 mpg's with intake and tune. My trip computer said 85 miles after going through 3/4 of a tank but my computer said i had 60 miles until empty. Yet the computer says I'm getting 11.0 mpg. Well that means i should be getting 155 miles per tank yet in reality i only was getting 145. Also how did I use 85 miles using 3/4 of a tank but with 1/4 tank left still have 60 miles to go?