View Single Post
Old 05-18-2014, 12:40 PM   #4 (permalink)
t vago
MPGuino Supporter
 
t vago's Avatar
 
Join Date: Oct 2010
Location: Hungary
Posts: 1,807

iNXS - '10 Opel Zafira 111 Anniversary

Suzi - '02 Suzuki Swift GL
Thanks: 828
Thanked 708 Times in 456 Posts
Quote:
Originally Posted by oldbeaver View Post
There is the posible fuel leaks I know well and the space issue too, you must arrange them and the hoses in little room, but if they work well, I would do the effort.

On the other hand, the rpm and tps method is less precise, but a lot less invasive in the car, you will never have fuel leaks this way.

My objective to retrofit such a device in the car (whichever) is not to know exactly how much fuel the car is spending, but to have a real time and objective COMPARISON instrument. For what? For knowing mechanic mods, tire pressure, driving habits, "fuel economizers", aero mods, etc. real effect in fuel economy.
Measurement will always present some errors. You can have mechanical friction in the measurement device, you can have leakage within the device itself, and you can have electrical delays in the device output. Similarly, you can have lag in your code, and electrical delays in your sensors. In both cases, yes, there are also calibration issues to contend with, as well.

There are also unforeseen drivers that will subtly affect your desired output. For instance, I have noticed that the mathematical model, presented in your excel attachment, does not deal with fuel enrichment pumps that operate with large changes in throttle.

The trick is to obtain reliable repeatability. With whatever method you use, it has to reliably agree with the "divide all miles driven with a tank for the gallons of fuel used" method.
  Reply With Quote