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-   -   Fuel consumption during Hill Down (no gas pedal deflection) (http://www.f150forum.com/f68/fuel-consumption-during-hill-down-no-gas-pedal-deflection-175326/)

fokker 10-06-2012 09:03 AM

Fuel consumption during Hill Down (no gas pedal deflection)
 
Fuel consumption during Hill Down (no gas pedal deflection)

With an OBD Scanner, i've seen, the 150 2000 5.4 consumes Fuel while i'am driving down Hill.

Is this Normal?
I think, the Engine should consume no Gas in an negative thrust/torque Situation (German "Schubbetrieb" or "Schubabschaltung")

what could be wrong?

MPETE 10-06-2012 09:31 AM

if the engine is running, its consuming fuel. that is internal combustion engine 101. if you are concerned its using TOO MUCH fuel while going down hill not under power, then I'd say your best bet is to drop the trans into neutral and let it idle while coasting down hill. however, I am a bit leary (sp?) of doing this myself because when you pop it back into drive its essentially putting stress on the trans similar to what a neutral-drop would do.

fokker 10-06-2012 11:40 AM

sorry thats crap...
Every Car i've ever driven, (except a 1983 Car) shut of the Injection, in negative torque Mode.
Gas Pedal Not Pressed, and rpm above idle -> then there is no need to inject fuel and most, if not all, of Cars shut fuel injection

EFI cars enter decel cut-off when the conditions are right: throttle closed, rpm high and in some cases speed above a certain limit. NO FUEL IS delivered.

It's called
Deceleration Fuel Cutoff (DFCO)


and it seems either it is defective or f150s doesn't cut off Fuel during overrun.

XtraLargeTall 10-06-2012 11:42 AM

Way to answer your own question...

fokker 10-06-2012 04:50 PM

No. I even don't know if it is defect or not implemented...

BigRick85 10-06-2012 06:04 PM

Quote:

Originally Posted by fokker (Post 2082945)
sorry thats crap...
Every Car i've ever driven, (except a 1983 Car) shut of the Injection, in negative torque Mode.
Gas Pedal Not Pressed, and rpm above idle -> then there is no need to inject fuel and most, if not all, of Cars shut fuel injection

EFI cars enter decel cut-off when the conditions are right: throttle closed, rpm high and in some cases speed above a certain limit. NO FUEL IS delivered.

It's called
Deceleration Fuel Cutoff (DFCO)


and it seems either it is defective or f150s doesn't cut off Fuel during overrun.

If no fuel were being delivered then the engine would cut off

fokker 10-06-2012 06:46 PM

READ
Quote:

With an OBD Scanner, i've seen, the 150 2000 5.4 consumes Fuel while i'am driving down Hill.
Quote:

and it seems either it is defective or f150s doesn't cut off Fuel during overrun.
That means, there is no DFCO, Or it is defect.
And my Question is, should the 2000 F150 5.4 Triton have DFCO, and Why doesn't work it at mine?

It burns fuel down Hill approximately 45mpg (or 5-6l/100km)
Is this normal? Yes No
if No Whats wrong?

bubbabud 10-06-2012 07:15 PM

Quote:

Originally Posted by fokker (Post 2083561)
READ


That means, there is no DFCO, Or it is defect.
And my Question is, should the 2000 F150 5.4 Triton have DFCO, and Why doesn't work it at mine?

It burns fuel down Hill approximately 45mpg (or 5-6l/100km)
Is this normal? Yes No
if No Whats wrong?

Your whole premis is wrong about EFI shutting off fuel at least up to 2011 Ford systems except the 6.2 Most cars and trucks when coasting just uncouple the trans but must maintain fuel to idle the engine. the new Ford 6R80 trans remains in gear untill almost completly stoped then the converter unlocks and the fuel is completly shut off until it unlocks thats why its foolish to shift into neutral when slowing you will use more fuel to maintain idle

fokker 10-07-2012 04:01 AM

Quote:

Most cars and trucks when coasting just uncouple the trans but must maintain fuel to idle the engine
thats wrong, If it is so, u cannot drive a hill down with Enginebrake.
....
When i drive a Hill down, there is nothing which uncouple.
The Transmission stays in the selected Gear, the only Option i have, ist to select a lower gear, for more Engine-Brake.
Or select Neutral. (Not good while coasting Downhill)
(With Automatic Transmission, shifting to N while driving downhill, can Kill the Transmission. I will never do that. )
....
I know no Car which have no DFCO except my 2000 f150 Truck.
....
Also my S80 Auto trans Volvo has DFCO
My Old Manual WV Golf has DFCO
My selled Audi's (Diesel and Gasoline) had DFCO
....

bubbabud 10-07-2012 09:09 AM

Perhaps I should have worded it differently. most vehicles when slowing or decending grades with the throttle closed will unlock the convrter to allow the engine to to idle down and use less fuel but with the vehicle not pushing the engine some fuel must flow to maintain idle. just watch the Tach and you will see the rpm drop when you take your foot off the gas and the vehicle speed remains the same.[little or no engine brakeing] unless you down shift. The new ford system maintains converter lock and actualy down shifts by itself to maintain engine rpm and allow for complete fuel cut off until you have slowed to a speed near idle and then fuel is turned on to maintain idle. As for diesel if you have mechanical injecters you must maintain some fuel flow as they are lubricated by the fuel. With electronic injecters you could cut fuel without harm but I dont have any knowledge about whitch if any diesel vehicles use 100% fuel cut of. As to your origanal ? Is your scaner reading actual real time fuel flow or is it averageing it over a set time frame? All so note some vehicles now actualy allow the engine to shut off at a stop for a short time and then restart when you step on the gas. BMW for example.To make a short story long I think your vehical is just fine just drive and enjoy.:thumbup:


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