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-   -   A very minor point (https://electricvehicleforums.com/forums/honda-civic-hybrid-12/very-minor-point-3986/)

Schwa 10-06-2005 11:04 PM

Re: A very minor point
 

Originally Posted by malditos
also another thing that I can't quite seem to figure out from all the past posts after searching... when one is gliding with the ICE off, how long does powersteering and powerbrakes work for? Do they have a time average before they quit and the car becomes a real hazard or do they just simply always stay on? has anyone tested this?

The car's power steering is electric, so as long as the car's electronics are "on" then you still have power steering. The power brakes are not electric boosted, so you only have a few boosted pumps of the brake pedal before you have full manual brakes and the ICE needs to come on again to create vacuum, but it's not really a time limited event. ABS still works with the ICE off and electronics on.

Tim 10-07-2005 06:38 AM

Re: A very minor point
 

Originally Posted by malditos
...and while we're on the subject of saving gas. Is there any real noticable difference when one glides and turns off the ICE versus just shifting to neutral with the ICE on?

also another thing that I can't quite seem to figure out from all the past posts after searching... when one is gliding with the ICE off, how long does powersteering and powerbrakes work for? Do they have a time average before they quit and the car becomes a real hazard or do they just simply always stay on? has anyone tested this?

Whether you notice it or not would greatly depend on how often you could do it. If you can glide with the ICE off for 5 miles a day - yeah, you'd notice (however, that a lot of downhill to find). If you're gliding 1/4 mile in a 20 mile commute, I doubt you'd notice any difference versus just staying in neutral.

Power steering and brakes are available (powered) for a time, then they go unpowered. I'll leave it to someone else who does this regularly to comment on how long, but it does run out. You can still brake and steer mind you, just without power assist.

Personally, I do not have any safe places to glide with the ICE off, so I use neutral.

zimbop 10-07-2005 07:08 AM

Re: A very minor point
 

Originally Posted by malditos
...and while we're on the subject of saving gas. Is there any real noticable difference when one glides and turns off the ICE versus just shifting to neutral with the ICE on?

Yes, one is much safer than the other. :-)

I use neutral without turning off the car and it effects my FE significantly. I really don't think it makes much difference whether you turn the car off or not. When the bar shows 120+ mpg, whatever gas you're using at idle is insignificant IMHO. Think about it, when you're stopped in traffic idling, how long does it take for the mpg display to tick downward? Pretty long in my experience, if I were going 60 mph down a hill, I don't think this tiny amount of gas is enough to make any difference in the mpg. Weigh that against the safety considerations and it's a no-brainer for me.

However, others with much higher mpg achievements than me might tend to disagree. On the other hand, I don't have people flipping me off on the road either. :-)

Method 10-07-2005 02:36 PM

Re: A very minor point
 
"...and while we're on the subject of saving gas. Is there any real noticable difference when one glides and turns off the ICE versus just shifting to neutral with the ICE on?"

I'd love to know this one as well. Someone (was it Georgia?) was going to test this by taking the same route over, once in neutral and once with ICE off but I don't know if he ever did it.

As far as the other questions, power steering never shuts off, and the power brakes shut off after a certain amount of use. I can coast through my friend's neighborhood for about a quarter mile and pull up to the house with the car off, and since I was going to shut the car off anyway when I got there...it is no additional wear and tear on the engine. However, it is a pretty steep downhill through a neighborhood with a lot of braking to make sure I'm not doing 60 in a residential...and everyonce in awhile the power brakes run out before I get to the house.

lars-ss 10-07-2005 02:39 PM

Re: A very minor point
 
Here is the answer I think:

Even when you are gliding and the ICE is running, you are burning as much gas as you do when the car is IDLING. Seems to me that means "0 MPG" at that moment.

But if you are coasting with the car off, you are getting at LEAST 120 MPG, right, according to the realtime MPG meter?

Am I wrong in my thinking on this?

Civic Duty 10-07-2005 03:27 PM

Re: A very minor point
 
When you're coasting in neutral, you are burning fuel at the same rate as you are when idling, but you're still moving forward at a measurable rate of speed. So, the equation
distance traveled (MILES) / fuel consumed (GALLONS)
would have a real value - it wouldn't be zero. However, you can't even mathematically describe your instantaneous mpg when the ICE is off and you're moving forward - it approaches infinity because you have zero in the denominator. It's like getting extra credit for that tank's mpg - you add miles traveled without adding gallons burned. No wonder FAS does such wonders for fuel economy.

xcel 10-07-2005 03:37 PM

Re: A very minor point
 
Hi Method:

___GPSMan (Escape HEV owner) will be arriving at my home late tonight/early tomorrow morning and I hope to get the idle vs. ICE off tests done with the PZEV in the morning if he feels up to it.

___Zimbop, idling after a recent reset will show you how much fuel you are consuming while just sitting there per the FCD, not after 500 - 700 miles just as it is very hard to increase your current FE after 600 miles at let us say 51.5 mpg. You will see the 120 mpg peg drop off at a very slow speed vs. absolutely pegged the whole time you are in an AS/FAS.

___Good Luck

___Wayne R. Gerdes
___Waynegerdes@earthlink.net

bluecivichybrid 10-08-2005 07:31 PM

Re: A very minor point
 
i've seen much discussion here about coasting in neutral and gliding with FAS, but i have a question about coasting in gear with/without regen

I have a CVT HCH and part of my daily route includes a 4 mile stretch of road that is a slight downgrade with some curves. usually i pull out of school right onto this road while my car is still not warmed up completely (shows 2 bars on the temperature gauge) so that 4-5 bars of regenerative braking don't kick in automatically while i'm coasting.

I accelerate to 35 mph and then my feet don't touch the pedals for those 3-4 miles - all I do is steer. The car naturally speeds up and slows down due to minor changes in slope, but it sticks pretty close to 40 mph throughout those 4 miles, while my fe meter is pegged at 120 mpg.

other times when my car is warmed up more, or I have braked several times, automatic regen of 4-5 bars comes back, and I have to just barely touch the accelerator to keep the regen off. During this time, the FE meter is pegged at 120 mpg as well. Not sure if it actually uses more gas than in the first scenario.

so my question is: Does coasting in gear without regen/keeping auto-regen off yield the same mpg as FAS (infinite mpg)? If not, does it yield a practically high enough mpg that the difference between FAS and coasting in gear w/o regen is negligible?

I think the ECU shuts off fuel injectors while the car is coasting above a certain RPM (it keeps fuel injectors working at low RPMs so that the engine can return to idle smoothly), so essentially, coasting above threshold RPM (whatever it is) should be the same as moving with FAS.

Both cases shouldn't use any fuel, but coasting in gear keeps the engine braking effect, where the spinning wheels force the engine to keep spinning as well, with no fuel being injected. Please correct me if I am wrong about the fuel injectors being closed while the car is coasting above a threshold RPM.

Civic Duty 10-09-2005 01:01 AM

Re: A very minor point
 
I am certain that the fuel injectors still provide fuel at approximately the same rate they do for idling when at such speeds. Only in the new 06 HCH will this setup (medium speed coasting) result in no fuel consumption, due to the new i-VTEC engine. If the ICE is on in our 2005 HCHs, we're burning gas, end of story. Now, it's still going to be pretty darn good mpg, as in higher than the capacity of our FCD to measure (i.e. >120).

bluecivichybrid 10-09-2005 01:48 PM

Re: A very minor point
 
Thanks Robby,
I'll keep that in mind, but since I'm not that comfortable with FAS and there is plenty of cross traffic on my route (vehicles turning in from driveways and parking lots), i think i'll keep to coasting in gear. 120+ mpg is good nuff for me :)


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