Automatic Deceleration on hills?

[RGK53]

Regarding my 2011 Ex:
Is it normal to automatically decelerate while driving down hills? This is on clear, dry roads, and happens every time.
It happens to the point where, by the time I'm at the bottom of the hill, I'm traveling well below the speed limit, and it feels like I'm forcing the car to pick up speed.
The Terrain Management is set to normal conditions.

 

[peterk9]

Regarding my 2011 Ex:
Is it normal to automatically decelerate while driving down hills? This is on clear, dry roads, and happens every time.
It happens to the point where, by the time I'm at the bottom of the hill, I'm traveling well below the speed limit, and it feels like I'm forcing the car to pick up speed.
The Terrain Management is set to normal conditions.

Welcome to the Forum RGK53.:wavey:
I believe the answer is YES. It is due to the vehicle's Aggressive Deceleration Fuel Shut-Off (ADFSO) technology.
It is designed to maximize fuel efficiency. ADFSO temporarily interrupts fuel delivery and consumption when the vehicle normally slows down while maintaining normal engine operation. ADFSO uses the transmission to keep the engine running at a low, more fuel-efficient operating level whenever possible. Normal fuel delivery resumes when the vehicle reaches a low speed or when the driver accelerates.
I think this is what you are experiencing. I've been getting quite good at judging the distances to stop signs so that I can let up on the gas and have the vehicle 'coast' to the stop sign with minimal braking required. I only do that when there is no vehicle behind me.
ADFSO is also an important part of the vehicle's Smart Charging system which uses regenerative electrical charging of the battery when braking or decelerating by converting the moving (kinetic) energy into electric energy.

Happy motoring.

Peter

 

[RGK53]

Thank you for the welcome and the detailed explanation.

 

[1995E]

ADFSO is also an important part of the vehicle's Smart Charging system which uses regenerative electrical charging of the battery when braking or decelerating by converting the moving (kinetic) energy into electric energy.
Peter

Is this really true? This sounds like a system that only comes with Hybrids because Hybrid vehicles use regenerative braking. How would the Explorer accomplish this with no regenerative brakes?

 

[peterk9]

Is this really true? This sounds like a system that only comes with Hybrids because Hybrid vehicles use regenerative braking. How would the Explorer accomplish this with no regenerative brakes?

Yes sir. Because there is no additional engine accessory belt to energize the battery, this converted kinetic energy is used in turn to charge the battery to allow the electrical system to function at an optimum operating level.

Peter

 

[Bill #5 Explorer]

Maybe you have your hill desent button pushed, and don't know it?

 

[182RG]

Maybe you have your hill desent button pushed, and don't know it?

That only works below a certain speed.

 

[jreask]

My wife's EX downshifts by itself on hill descents. This is without the cruise on. It would seem that any downshift would decrease fuel economy. The EX now has 3500 miles on it. The fuel economy has never been better than 19.7 MPG including one fill after 98% highway driving at 70 MPH. This is a far cry from the advertised 23 MPG from Ford. My wife drives like an old lady so I don't think it's her fault that the MPG are so low. Heck, my 98 4Runner gets 19 and it's 14 years old. That new 2012 4Runner is looking better everyday.

Joe

 

[1995E]

The automatic deceleration should have been programmed to turn on only when you press the brakes going downhill. My guess is that Ford want you to be able to maintain your speed going down hill and not pass the speed limit and not have to hold the brakes so much going down hill which eats your brakes up.

I think it should have been done to maintain a certain speed when a person brakes to a certain point and stops.

 

[peterk9]

My wife's EX downshifts by itself on hill descents. This is without the cruise on. It would seem that any downshift would decrease fuel economy. The EX now has 3500 miles on it. The fuel economy has never been better than 19.7 MPG including one fill after 98% highway driving at 70 MPH. This is a far cry from the advertised 23 MPG from Ford. My wife drives like an old lady so I don't think it's her fault that the MPG are so low. Heck, my 98 4Runner gets 19 and it's 14 years old. That new 2012 4Runner is looking better everyday.

Joe

Joe, the 70 MPH would be one reason why your MPG's are down. I read that a study done by the department of energy stated that most vehicles will hit their adverised MPG at 55 MPH. As speed increases your mileage decreases. At 60, for example, the decrease is 3%, at 70 it is 17%. Going 65 will lower the mileage 8%. For those who like to drive 75 or 80 MPH, they can expect a decrease in efficiency of 23% and 28% respectively.
Last summer I drove a 6 miles stretch at 50 MPH with ACC on and attained a 34 MPG reading. Taking into account your gallon is 20% smaller, that would work out to 27 MPG on a U.S. gallon, if my math is correct.

If your wife takes her foot off the gas when going downhill, and effectively is coasting, then the ADFSO kicks in by interrupting the fuel flow to the engine.
That is where you save on consumption.

Peter

 

[RGK53]

On one particular hilly road that I travel daily, I'm having to step on the gas to accelerate, while my car still wants to decelerate. The speed is 35 on this road, and the car slows down to below 30, with cars lined up behind me.

When this happens, I see the fuel economy gauge dip. That's where I understand what Joe is talking about.

 

[peterk9]

On one particular hilly road that I travel daily, I'm having to step on the gas to accelerate, while my car still wants to decelerate. The speed is 35 on this road, and the car slows down to below 30, with cars lined up behind me.

When this happens, I see the fuel economy gauge dip. That's where I understand what Joe is talking about.

If that is the case then I think something isn't right. The ADFSO should only kick in when you are slowing down or coasting. It should not work when you are accelerating or using the accelerator to maintain speed.

Peter

 

[2TimingTom]

Yes sir. Because there is no additional engine accessory belt to energize the battery, this converted kinetic energy is used in turn to charge the battery to allow the electrical system to function at an optimum operating level.

Peter

Isn't there an alternator always present? And that alternator is connected to the crankshaft via a belt. And when the engine is running, the alternator is spinning and charging the battery. Even when coasting down a hill and the injectors are shut off, isn't the engine crankshaft still spinning? Thus still charging the battery?

Is that what you (and Ford) mean by "smart charging system"?

If that's the case, nearly all fuel injected cars use this same technology.

 

[peterk9]

Isn't there an alternator always present? And that alternator is connected to the crankshaft via a belt. And when the engine is running, the alternator is spinning and charging the battery. Even when coasting down a hill and the injectors are shut off, isn't the engine crankshaft still spinning? Thus still charging the battery?

Is that what you (and Ford) mean by "smart charging system"?

If that's the case, nearly all fuel injected cars use this same technology.

The correct term is actually Smart Charging Alternator. It is a "regenerative electrical charging system that optimally charges the battery instead of having the alternator charging the battery anytime the engine is running. Smart Charging increases alternator output when the vehicle is braking or decelerating, converting the moving (kinetic) energy into electric energy. Since there is no additional engine accessory-belt load to energize the battery, the captured energy is used to charge the battery and maintain optimum operating levels of the electrical system."

This is info supplied by Ford. I am not an engineer and do not know exactly how it works as to when or how much the alternator charges the battery at any given time. It seems the systems may work in conjunction with each other.
I'm not implying that other manufacturers don't have a similar setup, just that it is new to the Explorer.

Peter

 

[VinceL]

My understanding is that these "smart charging" alternators are still connected with a belt, but also have a clutch on them. This way, if the battery charge level is okay, the clutch disengages and the alternator pulley freewheels with the belt. If the battery charge level drops to a certain point, the clutch engages and the alternator is then spun to charge the battery. This way, the drag created by the alternator is there only when needed. It is akin to the A/C compressor on the car, only engaged when needed.

 

[Tavin]

RGK53, welcome, my Explorer XLT 2011 I also slow down and increase the speed almost every day on the way home to work, sometimes a little uncomfortable since arriving at the end of the hill there are still a few seconds to be accelerated to switch to higher speeds and lower revolutions, in my case I opted to change it to manual at the bottom of hill and quickly speeds up manually, and solved the problem, Greetings