BlackShelbyGt500

hey guys i used to be able to tap off on my gas at 217 mile before empty but lately when i put gas on the car if would tap off and it would only say 187 to E. any idea on why this is happening?

THS_Steed06

What year is your Shelby? I've heard of some problems with the fuel tank float sensors getting sticky in winter. If its not rising all the way up it could be telling the ecu it has less gas than it does?

Try seeing if when you get down to 5 or 10 miles left to E how many gallons you are putting in. If its less that 14.7 or 14.8 it may be a good test of the fuel level in the tank.

Just a thought.

Tom

sbradle4

Also could just be the winter fuel blend. With all the extra additives, it's less efficient. This the first time you have noticed the drop in projected miles to E though, I assume.

BlackShelbyGt500

i actually had it down to 1 mile to E but i never really pay attention on how many gallon i put on it. its 2008. IS IT A 16gallon tank you think?

BlackShelbyGt500

i think the last time i actually had it to 200+ miles was a few months ago.

sbradle4

My 2010 GT gets 1-1.5 mpg less in the winter. So almost 20 miles less at 13 gallons (typically how much I fill up)

Nuke

Using the "Miles to empty" method of determining your fuel mileage (and any related issues) is a very inaccurate way to do business.

Are you doing any hand calculating from fillup to fillup? That would be your most accurate method. If not, then you need to reset your onboard at each fillup.

Driving style, where you drive, ethanol content, ambient conditions, vehicle condition.... these all have a major impact on fuel mileage. I often see as much as a 10 MPG difference between my city driving and long distance cruise mileage on my GT. Also, how accurate is your speedometer? Have you compared it to a GPS? People will often change gears or tire size and don't correct the PCM for these changes which throw off the on-board.

07BLACKGT

I thought the miles-to-empty fluctuated with the average MPG, so when your MPG figure goes down, you will have less "miles to empty." I could be totally wrong here.

Nuke

I believe you're correct. But my personal issue with even paying attention to "Miles to Empty" is that it can read "0" and you still have an unknown amount of fuel in the tank in most cases so it's use as a comparison from one tank to the next is pointless, unless you're tracking the exact # of miles you drive until you literally run out of fuel (and who's stupid enough to do that?).

chub46

If you are topping off when you fill up with gas I recommend not doing that. When the gas pump stops remove the nozzle. Topping off could mess up your fuel sensing system.