Fuel consumption computer off by over 1 gallon??
#1
Fuel consumption computer off by over 1 gallon??
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
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
#3
RE: Fuel consumption computer off by over 1 gallon??
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.
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.
#6
RE: Fuel consumption computer off by over 1 gallon??
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.
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.
#7
6th Gear Member
RE: Fuel consumption computer off by over 1 gallon??
ORIGINAL: ChiDiddy
...it only calculates MPG based different inputs like throttle position, speed, etc, does not measure actual fuel usage coming out of the injectors.
...it only calculates MPG based different inputs like throttle position, speed, etc, does not measure actual fuel usage coming out of the injectors.
#10
RE: Fuel consumption computer off by over 1 gallon??
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?