Hi, I have a 2008 FEH FWD. I find that with very careful effort on the accelerator pedal, I can get the HEV display to say "Idle" when coasting
down a hill in Drive. Will this give me the same MPG result as coasting down a hill in Neutral?

Thanks, Ken

 

NO!

 

well in my experience also having a 08 with nav and also a scII if I go down a hill and hold the pedal down just enough for the display to show "idle" the scan gauge might show something like 160mpg but if i put it into neutral it might show like 170mpg but after a few seconds then the flow screen shows power going to the wheels and the mpg drops to like 120 or so. If I put it into drive again and hold the acc pedal so that the screen shows idle again then the mpgs go back up to the 160-170 range. just my 2 cents!

 

Gary, based on your experience, do you get higher MPG readings coasting in Neutral or modulating the accelerator pedal to maintain an "idle" condition while in Drive?

I have also seen the power screen showing power going to the wheels duing a Neutral coast, but I can elimanate that if I stay in Drive and maintain the idle condition.

Thanks, Ken

 

Ken, this discussion of neutral coasting vs deadbanding in "D" or "L" has gone on for years, and I've always suggested neutral coasting. For hybrids (Toyota) that will not stay in EV after shifting to neutral, deadbanding may be a better choice.

About 2 years ago, I worked with Wayne Gerdes here to find the best way to Pulse and Glide the FEH. I went out to a country road and did countless test gliding in "D" with the engine on and off and "N" with the engine on and off. The test was to determine how far the FEH would glide from 40mph to a stop. Neutral coasting had a 36-38% longer coast to a stop.

There are a number of factors in deadbanding the FEH you should consider. There is power going into and out of the eCVT. MG-1 is working to control the engine idle while MG-2 can provide torque or regen to and from the wheels. As you press the accelerator, regen is in a stop and go mode, and so is torque. You don't see any arrows, but none the less it's happening. It's like the creep mode in EV, your moving but your still at an idle with no arrows. An example of regen not showing up on the energy screen because of so little current, is when you let off the gas pedal in EV, the arrow drops out at about 27mph and below. There are two reasons the FEH/MMH will show a instant higher MPG while the engine is running. The idle is controlled by MG-1 and regen reduces MPG. However, HV battery power is used by MG-1 to control idle and MG-2 is using power to balance torque. The more torque you add at the accelerator pedal, the longer your glide will be.

With neutral gliding, there is no regen and MG-1 will use the engine to generate power above 6mph to charge the battery if needed. The engine controls the idle, not MG-1. Applying the brake pedal lightly can reduced that idle and will go EV below 40mph. The advantage of eliminating regen and coasting 36-38% further and longer with yield better overall MPG averages without a drain on the HV battery by the eCVT. Gaining speed going down a hill at no cost from the HV battery is another advantage to increase MPG. Neutral coasting has a big advantage in EV under 40mph because it allows you to slowly reduce speed.

So, the choices are deadbanding at the expense of the HV battery at a lower idle in general and getting better instant MPG. With deadbanding, the longer you glide compared to "N" coasting is a matter of draining the HV battery more. With neutral coasting, regen is eliminated for a 36-38% longer coast, no HV battery is drained by the eCVT and you get to charge the HV battery for EV at ~9,999mpg later.

GaryG

 

GaryG, I really appreciate the time you took to give me a detailed explaination of what is going on. I have a lot to learn. I have about 2800 miles on my FEH so far, my best has been 35MPG, but cold weather is now setting in and so far this current tank is running about 31MPG.

Thanks again, Ken

 

I have 700 miles on my MMH, and 31 is about the best I can do with the below 40 weather also.

My friend that is certified to work on them at a Ford Dealer suggested that I keep the engine running as much as possible so that the motor breaks in better. I guess with the cold weather that is easy to do. I know most engines need 3-5k miles to break in good and get good gas mileage. I would guess since most of the load is handled by the electric engine, it takes longer to break in completely.

I have a K&N airfilter on the way, I am hoping that lets the engine breathe a little better for more complete combustion.

Has anyone considered putting in high performance spark plugs?

 

Hi Ken.

GaryG gave you a very detailed, but somewhat incorrect, or at least incomplete answer. Hopefully, I can give you the full picture.

The FEH in MOST CASES, MOST OF THE TIME will coast exactly the same in an "idle" or "deadband" condition, as it will in a Neutral position.
Neutral, by technical definition is "deadband coasting".

NONE of Gary's tests addressed this scenario.
Gary found he can coast farther in N compared to D with his foot totally off the go pedal in both cases. Well, that was not new news! I'm sure all new drivers realize that within a few days of ownership.

If you do put your foot slightly on the pedal as you describe, and get zero arrows on the screen, the car is using from zero, to at most, 500 watts of power. ( 0.5 kW ). The gauges that produce the energy flow arrows are not sensitive enough to display less than 0.5 kW, but I have meters that can show much more detail, and there is not any power flowing in a true deadband, idle coast in D. Most of the time when you see zero energy arrows, zero energy is being used, or produced, but it is possible for there to be a "trickle" of power, sometimes.

0.5 kW is just a trickle, since
driving in EV takes 5.0 to 25.0 kW, and regen brake produces about the same range.

So in reality, if you learn to "deadband" or "idle" coast properly, and become skilled at it, it is the same as coasting in Neutral. I have proven this to dozen's of owners, including GaryG, and the fact that nothing mechanical happens when you move the shifter to "N". The shifter is really just a computer input, like a joystick, and you can signal the car with your hand on the shifter, or your foot on the pedal, and get 100% the exact same result.

GaryG has said over and over again that the hand shift method is easier for him, so he does most of his coasting by moving the shifter to N and letting his foot relax. I tend to really like the foot method, especially if my hand is on a hamburger or cup of coffee and the other hand is where it should be, on the wheel.

I PROMISE 99.9% of the time, there will be no difference in the two methods. Now, you only have to find what you like best!
Cheers! -John

 

Yep, don't waste your money. I tried some Bosch +4s which in other DOHC fast burn combustion chambered vehicles this would give a little low end torque increase but not on this miller cycle engine. So I've got a set of $25 platinum +4 plugs that didn't do squat, but they didn't hurt the mileage or the performance just the wallet.

 

Your welcome Ken. Many of the things I've learned is from the workshop manuals and reading every Ford patent related to the FEH/MMH I could find. During my road test, most often I discovered something I wasn't looking for. This regen discovery while driving in "L" and "D" was simple to understand when I seen the results.

Pasted below is from the article I wrote at Cleanmpg.com. This was the result of another test for Wayne Gerdes that was presented at the '06 Hybridfest. You can see my comments about getting more regen and less MPG even in cruise control. I never saw any arrows indicating regen, but it was clearly reducing MPG. The pasted chart didn't come out below, but you can go to the article to see it. http://www.cleanmpg.com/forums/artic...brid--350.html


Besides the various techniques to improve the FEH’s around town FE , her steady state FE capabilities are very good in their own right. All tests were performed over a 1.0 mile distance with tire pressures set to 52 #’s in mid 90 degree F temps.


The differences between using Cc or not at the above test speeds on an absolute flat roadway with no traffic interaction are statistically insignificant in the FEH.

Important: Many of us drive in low gear ("L") thinking we are in the same state as drive ("D"). During my tests, I accidentally left the shifter in "L" and came up with astounding results. It appears that "L" at below 50 mph, there is still regenerative braking occurring while in cruise control. This must also be the case while not in cruise control. The result I was getting was a 5.1 MPG reduction at 30 mph while in the "L" position over the "D" position. At 40 mph, I was getting a 4.1 mph reduction in "L" over the "D" position. To sum it up, I will no longer be using the "L" position in the steady state cruising mode. In addition, I believe that using "L" in EV mode may reduce fuel efficiency. This is sort of like saying the "L" position causes an accelerate or brake (regen) "L" mode, instead of an accelerate and (light regen)"D" coast mode. Based on these test, I recommend using "L" for going EV and charging the battery only. Driving only in "L" will reduce your FE.

End of Paste

Test like these have changed my driving habits and I have seen better results in my average MPG.

GaryG