Tec80

Reading about the EcoBoost 3.5 update, which finally adopted Toyota's D4S (10 years late, LOL):

http://m.wardsauto.com/test-drives/p...370414568b1686

In this article, they say this: "The biggest change comes in the fuel-delivery system, where Ford engineers added low-pressure port injection to augment high-pressure direct injection already in place on EcoBoost engines. The extra fuel-delivery system allows engineers to shut down the direct-injection system and its mechanical pump at low speeds and under low loads, reducing friction losses and emissions. Employing both systems at start-up cuts cold-start emissions as well, Ford says."

I thought of the switching of the 2 systems, which D4S probably does. And then thought of the hesitation issue. Could this be due to some issue with the Direct system switching on (or some problem with it not doing a smooth "baton pass" from Port to Direct mode under WOT conditions? Hmmmmm....


Side note: A big reason (that the article omits) for addition of Port injection is that the Direct-only strategy caused issues with intake valve deposits, because no fuel washes the intake valves as with port injection.

Doublebase

I think you're going to see more and more manufacturers start to do this, they are tired of the carbon issues. The problem is cost; to have two fuel delivery systems is expensive, you're talking about adding many more injectors, a fuel rail, pressure regulator, on and on. The article stated that the high pressure fuel pump would be turned off...can't see how that would happen if it's driven off the camshaft, which all hp fuel pumps are. It would probably just dump fuel through the solenoid on the pump, which is monitored by the fuel pressure sensor (like most systems).

I have no idea if the two systems causes hesitation in our cars, I think it has more to do with knock sensors retarding timing, but who knows. Fuel delivery usually isn't a problem in terms of getting it to where it needs to go quickly...and quantity isn't a problem either. Air is usually the problem...getting it there quick enough and forcing enough into the engine. But I never thought about a hesitation between the two systems.

One thing for certain, these high pressure fuel pumps are expensive and we've got two of them to worry about. The injectors are expensive too, and I can't imagine these things will just easily come out after spending it's life baking inside a combustion chamber and cylinder head. I pray I never have to worry about the fuel system on my car.

roadfrog

99% of hesitation issues occurred imediately after an oil change.