Why doesn't ICE cut off automatically when coasting?
#11
03-25-2007, 10:10 PM
Re: Why doesn't ICE cut off automatically when coasting?
I'm not trying to pick a fight (I honesty wasn't the last time), I'm just asking a question because I DON'T know the answer.
Do we know if this saves any gas on the FEH? Some people seem (erroneously or not) to believe there is no gas flowing to the engine in such cases anyway.
The NAV goes to max during those times, however that really just indicates >60MPG. I see on my scanguage that the number is pretty high much higher than 60 which agrees with the NAV. However.... its certainly not 9999MPG which is what the scanguage reads when you are in EV mode and there is NO gas flowing.
Somewhere I thought I remember reading that the Scanguage doesn't actually measure fuel flow but instead infers it from the RPM and such.....
is it possible that the reading on the scanguage is in error because it sees an RPM and assumes there is fuel flowing and these other posts are right. Or is the above statement about the scanguage in error and the scanguage is reading correctly.
I haven't tried the key off or anything so I'm curious.
Do we know if this saves any gas on the FEH? Some people seem (erroneously or not) to believe there is no gas flowing to the engine in such cases anyway.
The NAV goes to max during those times, however that really just indicates >60MPG. I see on my scanguage that the number is pretty high much higher than 60 which agrees with the NAV. However.... its certainly not 9999MPG which is what the scanguage reads when you are in EV mode and there is NO gas flowing.
Somewhere I thought I remember reading that the Scanguage doesn't actually measure fuel flow but instead infers it from the RPM and such.....
is it possible that the reading on the scanguage is in error because it sees an RPM and assumes there is fuel flowing and these other posts are right. Or is the above statement about the scanguage in error and the scanguage is reading correctly.
I haven't tried the key off or anything so I'm curious.
Key-Off FAS is another control at our means to stop energy from being used. Have you looked at your energy bill lately? Mine is getting better for a reason.
GaryG
#12
03-25-2007, 10:32 PM
Re: Why doesn't ICE cut off automatically when coasting?
I could see spinning the ICE to keep AC going or keep water circulating (and somewhat warm), and because using it as an air pump (with the injectors off) slows the car without the wear/damage to brake pads from a long coast. If the battery is full, or being charged at the maximum rate, the energy is going to get wasted, so it's a matter of how best to disperse it. Using it to spin the AC pump isn't a complete waste.
This is just my speculation....no documentation. It wouldn't hold true on a conventional carburated engine, but on something with injectors, you can spin it and use no fuel.
This is just my speculation....no documentation. It wouldn't hold true on a conventional carburated engine, but on something with injectors, you can spin it and use no fuel.
#13
03-26-2007, 04:49 AM
Re: Why doesn't ICE cut off automatically when coasting?
I agree Andy, if I needed AC, that would be a good time to use the ICE.
This is the way I would take a long downhill I think. First, try to drain the HV battery as much as possible before the downhill. Traffic permitting, shift to neutral and let the downhill develope your speed in EV. For a long downhill when you know your going to fill the battery, shift to "D" and apply brakes to slow. Using "D" and the brake pedal will slowly fill the battery with regen will help prevent overheating the traction motor (as a generator) and the HV battery. If I needed to exceed 40mph, Key-Off FAS in neutral would be my next choice. Above 40mpg, and if I still needed to slow and charge the HV battery more, I would restart, shift to "D" and apply the brakes. Using "L" will cause the run-up of the ICE most of the time, using "D" and the brake pedal will slowly allow regen and prevent run-up most of the time. One reason I don't like the run-up is because it screws up the trip information on the SG. I would Key-Off FAS in neutral above 40mph while still maintaining speed after the battery is full. For any stops or speeds below 40mph, I would restart at an idle 30 seconds before the slower speed to go EV at 40mph and below. It takes 30 seconds after a restart to go EV, so I would be prepared to take off from a stop in EV.
BTW, the Prius cannot restart like the FEH/MMH in neutral after a FAS. A quick bump of the key for a restart in neutral above 6mph will let you shift to "D" for acceleration if needed at any time in our vehicle. As far as using the brake pads and neutral to prevent a run-up, I do it because the pads don't get much wear with regen anyway.
GaryG
This is the way I would take a long downhill I think. First, try to drain the HV battery as much as possible before the downhill. Traffic permitting, shift to neutral and let the downhill develope your speed in EV. For a long downhill when you know your going to fill the battery, shift to "D" and apply brakes to slow. Using "D" and the brake pedal will slowly fill the battery with regen will help prevent overheating the traction motor (as a generator) and the HV battery. If I needed to exceed 40mph, Key-Off FAS in neutral would be my next choice. Above 40mpg, and if I still needed to slow and charge the HV battery more, I would restart, shift to "D" and apply the brakes. Using "L" will cause the run-up of the ICE most of the time, using "D" and the brake pedal will slowly allow regen and prevent run-up most of the time. One reason I don't like the run-up is because it screws up the trip information on the SG. I would Key-Off FAS in neutral above 40mph while still maintaining speed after the battery is full. For any stops or speeds below 40mph, I would restart at an idle 30 seconds before the slower speed to go EV at 40mph and below. It takes 30 seconds after a restart to go EV, so I would be prepared to take off from a stop in EV.
BTW, the Prius cannot restart like the FEH/MMH in neutral after a FAS. A quick bump of the key for a restart in neutral above 6mph will let you shift to "D" for acceleration if needed at any time in our vehicle. As far as using the brake pads and neutral to prevent a run-up, I do it because the pads don't get much wear with regen anyway.
GaryG
I could see spinning the ICE to keep AC going or keep water circulating (and somewhat warm), and because using it as an air pump (with the injectors off) slows the car without the wear/damage to brake pads from a long coast. If the battery is full, or being charged at the maximum rate, the energy is going to get wasted, so it's a matter of how best to disperse it. Using it to spin the AC pump isn't a complete waste.
This is just my speculation....no documentation. It wouldn't hold true on a conventional carburated engine, but on something with injectors, you can spin it and use no fuel.
This is just my speculation....no documentation. It wouldn't hold true on a conventional carburated engine, but on something with injectors, you can spin it and use no fuel.
#14
03-26-2007, 04:56 AM
Re: Why doesn't ICE cut off automatically when coasting?
DO NOT key off above 40 mph. If you cause damage to the trans by doing this, Ford can and probably will find out - you will not be able to clear the codes that result to hide what you did. The damage will not be covered under warranty.
#15
03-26-2007, 06:02 AM
Re: Why doesn't ICE cut off automatically when coasting?
How so? I'm still figuring out exactly how the scanguage works.
#16
03-26-2007, 12:20 PM
Re: Why doesn't ICE cut off automatically when coasting?
Many places in the '05 Workshop Manual state this including Section 307-01B-2 under the eCVT Chapter. Under "Neutral" it states:
"With the range selector in NEUTRAL:
* no power flows through the transmission.
* the output shaft is disengaged from the drive wheels."
In addition, the owner manual states the you can tow the FEH with all four wheels down safely up to 75mph in neutral.
Programming allows two states of Neutral, "Active Neutral" above 6mph allows you to restart while on the move. "Passive Neutral" allows you to hold the engine in the state (engine on or off) it was in when enterred, but will not let you restart untill you shift to "Park".
With the drive wheels disengaged in "Neutral", a restart above 40mph should be like the software that prevents over spinning of MG 1 by an automatic restart by those same components. A Key-Off above 40mph will not allow any forward gear engagement in "D" or "L" until the engine is restarted. When I accidently shift while the engine is off, the vehicle remains with the output shaft disengaged. My Scangauge still shows no codes found. So far, no problems found either.
Bob, what codes are you talking about that can be found? And what components could be damaged? Any ref. would helpful.
GaryG
#17
03-26-2007, 12:34 PM
Re: Why doesn't ICE cut off automatically when coasting?
The Scangauge must not compare sensors like the PCM does. The SG sees the run-up, but does not see the fuel injector shut off according to Ron at Scangauge. As a result, the SG start to show a decrease in MPG as run-ups continue.
GaryG
GaryG
#18
03-28-2007, 10:38 AM
Re: Why doesn't ICE cut off automatically when coasting?
EV mode or not, you have to admit that having the engine running at an idle and getting 60+ MPG downhill is better than most other cars.
#19
03-28-2007, 05:26 PM
Re: Why doesn't ICE cut off automatically when coasting?
GaryG
Last edited by GaryG; 03-28-2007 at 05:33 PM.
#20
03-28-2007, 06:01 PM
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Re: Why doesn't ICE cut off automatically when coasting?
Gary, I have to also say that key-off above 40 MPH is a bad idea.
Coasting at high speeds in N, the ICE will rev up in RPM to match the speed of the wheels / MG2, or the MG1 will spin up the ICE to match the speed of the wheels / MG2.
With key off, you remove the car's ability to do this.
Below 40 MPH, this car can be a 2 part system, or 3 part system.
Above 40 MPH, this car must be a 3 part system.
MG1 / MG2 / ICE
Also, the "tow behind at any speed" does not apply to your case. When you tow behind, you gradually move from zero to 75 MPH and slowly go back down to zero. And when you tow behind, you never EVER shift to Drive, nor do you ever restart the car in motion. And there is a special procedure you do with the transmission before you tow behind. You do NOT just stick the key in and shift to N. Some people wonder if all the electronics will drain the battery if they leave the key in when they tow.
You Don't put the key into the car at all when you tow!!!
So all the electronics are 100% off when you tow.
( Didn't you know that Gary? )
Just because something is possible, does not make it a good idea.
P.S. Engineers are smart. Don't you think they would have loved to market a 50 MPG SUV by allowing automatic neutral coasting and EV at any speed?
There are very good reasons the car works like it does. Giving you limitations to "discover" and fix for Ford was not one of them!
Coasting at high speeds in N, the ICE will rev up in RPM to match the speed of the wheels / MG2, or the MG1 will spin up the ICE to match the speed of the wheels / MG2.
With key off, you remove the car's ability to do this.
Below 40 MPH, this car can be a 2 part system, or 3 part system.
Above 40 MPH, this car must be a 3 part system.
MG1 / MG2 / ICE
Also, the "tow behind at any speed" does not apply to your case. When you tow behind, you gradually move from zero to 75 MPH and slowly go back down to zero. And when you tow behind, you never EVER shift to Drive, nor do you ever restart the car in motion. And there is a special procedure you do with the transmission before you tow behind. You do NOT just stick the key in and shift to N. Some people wonder if all the electronics will drain the battery if they leave the key in when they tow.
You Don't put the key into the car at all when you tow!!!
So all the electronics are 100% off when you tow.
( Didn't you know that Gary? )
Just because something is possible, does not make it a good idea.
P.S. Engineers are smart. Don't you think they would have loved to market a 50 MPG SUV by allowing automatic neutral coasting and EV at any speed?
There are very good reasons the car works like it does. Giving you limitations to "discover" and fix for Ford was not one of them!
Last edited by gpsman1; 03-28-2007 at 06:14 PM. Reason: added P.S.
