throttle tap to initiate DFCO

[bestclimb]

Noted something a while a go and have been looking for it lately. When engine braking (with a down shift) I have noted that my Subaru does not always enter DFCO, even at higher RPM. However, when lifting off even at lowish RPM it always enters DCFO.

When coming down hill and down shifting if I don't feel computer has cut fuel or note that it is still in closed loop I can blip the throttle and it will go open loop and zero fuel consumption immediately. The "blip" is not even enough to feel, just enough for the computer to see a change in throttle position.

I will have to check for this in the escort.

[jedi_sol]

in for results...i just got a 2013 subaru sti...i dont have a scangauge yet so i can't tell if mine goes into dfco either.

[SentraSE-R]

DFCO parameters vary with the car. My '02 Nissan Sentra SE-R didn't enter DFCO unless it was in gear, engine rpms >2500, and relative TPS was at idle position (11?). That meant I had to be going faster than 65 mph in 6th gear for DFCO to kick in.

My '06 Scion xB, OTOH, is a DFCOing pleasure. It enters DFCO when in gear, engine rpms >1500, and relative TPS at idle (11). That means it goes into DFCO at any speed >35 mph in 5th gear.

FWIW, I've never had to blip the throttle of either of those cars (both manual trannys) to enter DFCO

[CrazyLee]

Originally Posted by bestclimb

Noted something a while a go and have been looking for it lately. When engine braking (with a down shift) I have noted that my Subaru does not always enter DFCO, even at higher RPM. However, when lifting off even at lowish RPM it always enters DCFO.

When coming down hill and down shifting if I don't feel computer has cut fuel or note that it is still in closed loop I can blip the throttle and it will go open loop and zero fuel consumption immediately. The "blip" is not even enough to feel, just enough for the computer to see a change in throttle position.

I will have to check for this in the escort.

IF DFCO means that the ECO cuts the fuel on decelerate, then I got it. My "The Beast" RV will cut the fuel mostly anything over 50 mph. The MPGuino shows 999 mpg. Lower than that it shows 60-30 mpg as it slows down. 454 Chevy w/ 4 speed automatic tranny.
I LOVE to coast! 16 mpg, best so far.

[cbaber]

Sometimes when I am engine braking the fuel will not shut off. If I apply a little throttle and resume engine braking, the fuel shuts off. I am not sure if this is is actually happening or if the Scangauge is just having a little glitch.

I wouldn't sweat it to much. If you are engine braking you have no load (negative load?) on the engine and the cars computer is not going to deliver hardly any fuel if it isn't cut off.

[bestclimb]

Originally Posted by cbaber

Sometimes when I am engine braking the fuel will not shut off. If I apply a little throttle and resume engine braking, the fuel shuts off. I am not sure if this is is actually happening or if the Scangauge is just having a little glitch.

I wouldn't sweat it to much. If you are engine braking you have no load (negative load?) on the engine and the cars computer is not going to deliver hardly any fuel if it isn't cut off.

What you describe is exactly the behavior the forester does. Ultra Gauge shows closed loop and 60-80mpg, slight tap on the throttle and then Ultra Gauge shows open loop along with 9999999. I can also feel a slight increase in deceleration.

Not much fuel but enough to harsh my grove. On sections where the computer does not shut off fueling I get 60-80 mpg, if I were to just coast at idle I would be getting 170+-50. Granted not not a large % of a hill but a bit of savings if aware of the behavior for no increase in travel time.

[jedi_sol]

I got my torque app installed. It seems on my 2013 Sti, dfco happens in any gear at any speed...as long as the rpms are above 1K rpm.

It seems this car is very liberal with dfco.

[roosterk0031]

With the cobalt I have to be at 2,000 rpm for DFCO to kick in (55 mph in 5th). I'll try the throttle blip at lower speeds on the way home. SGII mpg or gph doesn't pick it up, but goes open loop and factory gauge 99. Goes back to closed loop at about 1400 rpm and 40 mph.

Edit: tried on the way home, no difference tapping the throttle with the cobalt.