dcfluid

I just tested my truck on my highway fuel economy test loop and noticed a change in mileage. New I got 19 mpg, @3000km I got 19.5, and now @ 3760 I got 21.5 mpg. A very controlled consistent test.
So I noticed my oil life monitor was on exactly 80%. Perhaps this is how the break in time is monitored and now an adjustment has been made.
There seems to be no consistency as to what mileage people are seeing mileage improve, so here is some speculation that perhaps the computer monitors how the engine is driven thru a system similar to the oil life monitor. Makes more logic that way.

Perhaps we can start watching the oil life monitor and seeing if the 80% mark matches an improvement in mileage instead of the 5000km mark.

richterscale

There might be a connection to the oil life monitor, but I don't think it has to do with programming. As the oil life decreases, engine break-in has been increasing. The harder the engine has been run, the faster the oil life will near 100% and the closer the engine comes to full break-in.

dcfluid

Yeah, whatever the causes it would be nice to confirm mileage does increase at a certain point. I will definitely keep careful track and keep testing to discount any false readings or fluke results.
A 2.5 mpg increase from new is enough for me to celebrate success.
Now to make sure it holds true.

OmahaEcoBoost

I've definitely seen an increase in gas mileage from 500 to 2,500 miles. I expect it to continue for another 1-2,000 miles.

mrpositraction

probably getting some summer fuel now as well, just another variable to think about

engineermike

It is true that summer fuel has a higher BTU content than winter fuel, plus gasoline engines are more fuel efficient on hot air. Though, I've read that the difference is usually offset by running the AC

jdvaughn

Saying that gasoline engines are more efficient on hot air is a wobbly statement. I would agree with you that due to the extra latent heat on the air that less fuel would be required to reach optimal combustion but with warmer air you have less density (hence intercoolers on the ecoboost) and therefore poor combustion. There is a fine line there....

engineermike

I was referring to the increased manifold pressure required to get a given density at the hotter temps. For any given load requirement, the intake manifold pressure will have to offset the reduced density. Increased manifold pressure means the piston dP on the intake stroke is lower, leading to less pumping losses. It's part of the reason that Diesels (atmospheric manifold pressure) get better fuel mileage than gas (negative manifold pressure) and smaller engines get better fuel economy than big ones (higher manifold pressure to achieve the same power) - the very concept that makes the turbo v6 an attractive option.

Ideally, you could control the density of the manifold air by heating and cooling it rather than throttling it, but there are a lot of problems with that idea. If it were practical, gas engines would get the same mileage in cold and hot and they would do as well as Diesels.

I suppose there could be a case where the Ecoboost is running in boost at constant speed. That would be very hot weather and high speed. In that case, the exhaust pressure rises and you're back to high pumping losses.

truckerdude

how did your three tests compare in temperature, humidity and wind? If they werent exactly the same your results are skewed. They could also be skewed if for example, you did the three tests with the engine at different temps, as when cold the engine sucks fuel. also was the fuel from the same station each time. if your fuel has ethanol was the percentage the same each time.

How long was each of your runs?

dcfluid

I'm a little **** about things like this so you would need scientific equipment to get that little bit better, but that defeats the purpose of finding out ' what I get' vs. ' what can it get with a scientific experiment'.
All 3 of these runs were 90% plus humidity. Temps were 6,9, and 11° c.
Tire pressures 40 psi, winds calm, vehicle completely warmed up from driving before test, fuel was the same pump and station 87 reg non ethanol. I have tried our "up to 10%" 87 regular with no noticeable difference. 30 km round trip, reset trip meters and adjusted speeds at set markers and monitored on gps. No traffic impeding test.
I don't know how much more I could do to satisfy my curiosity as to fuel economy progress. I'm very confident with comparing these results to my other vehicles to see how the ecoboost is doing.