Fuel in fuel lines

[2015-MUSTANG]

I am changing from 87 octane to 93 since I'm going to run a 93 octane tune. I just filled up with 93. How much fuel is in the lines? I m wondering how long I have to wait/drive till I know I ve got 93 octane running in the engine?

Sponsored

 

[Renner]

I am changing from 87 octane to 93 since I'm going to run a 93 octane tune. I just filled up with 93. How much fuel is in the lines? I m wondering how long I have to wait/drive till I know I ve got 93 octane running in the engine?

I ran my 87 dry then 1/4th tank of the full 93 tank to be sure..

 

[cosmo]

How much 87 was in your tank when you filled it up with 93? 1/8th of a tank?

Safe bet is, is to run this tank of part 87/part 93 to at least 1/8th of a tank, fill it up again with 93, then load the tune.

 

[RubyRed15]

This thread is amusing.

 

[David@FFtec]

That's a good question. When you put 93 in the tank there's still 87 in the lines. The issue is that this car has a returnless fuel system. It's a common setup for a direct injection system. The only way for new fuel to reach the injectors is to go through the injectors and get burned off. From our testing on the direct injection returnless fuel system on the BMW N54 platform it takes approx 7 miles of driving to burn off the old fuel from the lines. We haven't tested this on our shop EcoBoost yet but a safe bet is to just drive normally for 5 to 10 miles before assuming the new fuel is being used.

 

[Dirtleg]

I've always wondered how much of the wrong fuel you get when using a gas pump with the single hose vs a hose for each grade of fuel and how much dilution occurs.
But these issues are essentially uncontrollable and best not worried about. But still the question remains.

Sponsored