Overhead MPG calc way off
#21
01-02-2008, 07:20 AM
RE: Overhead MPG calc way off
For the overhead MPG trip computer readout to be accurate
your injectors need to be clean and spraying the correct amount
and your fuel pressure feeding the injector inlets
needs to be near the center of the specified psi range.
If the overhead MPG reading is off by alot
and stays off over several tanks
that is a warning that injectors
are partially clogged or fuel pressure is off.
your injectors need to be clean and spraying the correct amount
and your fuel pressure feeding the injector inlets
needs to be near the center of the specified psi range.
If the overhead MPG reading is off by alot
and stays off over several tanks
that is a warning that injectors
are partially clogged or fuel pressure is off.
#22
01-02-2008, 10:58 AM
Captain
Join Date: Dec 2004
Location: New Castle Delaware
Posts: 679
Likes: 0
Received 0 Likes
on
0 Posts
RE: Overhead MPG calc way off
ORIGINAL: Foiled
Even if you use the same exact pump and handle every time you fill up, it is impossible for it to shut off with the same amount of fuel in the tank every time. The backflow shut off is set by the last person that tested it. There are too many variables to say that it will always shut off at the same tank level. Also the angle your truck is sitting will affect this. Even a low tire could cause you to get more or less fuel by using the backflow shut off as a fill indicator.
If you use the same formula to figure your MPG you will be able to spot a problem in your MPG very soon. But using the pumps reading and your trucks mileage for an exact MPG figure will only cause you headaches.
That's why the oil industry allows 3/10's plus or minus when calculating Gasoline. Gasoline expands and contracts depending on the ground temp. So you may not be testing against a true gallon ,plus or minus 3/10's.
ORIGINAL: Triph75
I get consist mpg with the hand calcs, and when I fill up I let the pump stop itself and then thats it, I know it can be different every time,
I get consist mpg with the hand calcs, and when I fill up I let the pump stop itself and then thats it, I know it can be different every time,
Even if you use the same exact pump and handle every time you fill up, it is impossible for it to shut off with the same amount of fuel in the tank every time. The backflow shut off is set by the last person that tested it. There are too many variables to say that it will always shut off at the same tank level. Also the angle your truck is sitting will affect this. Even a low tire could cause you to get more or less fuel by using the backflow shut off as a fill indicator.
If you use the same formula to figure your MPG you will be able to spot a problem in your MPG very soon. But using the pumps reading and your trucks mileage for an exact MPG figure will only cause you headaches.
That's why the oil industry allows 3/10's plus or minus when calculating Gasoline. Gasoline expands and contracts depending on the ground temp. So you may not be testing against a true gallon ,plus or minus 3/10's.
