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2007 Honda CR-V Rolling Resistance and Grade Logic

14 messages,  Last post on Sep 19, 2007 at 8:56 AM

You are in the Honda CR-V Forum.

What is this discussion about? Honda CR-V, Fuel Efficiency (MPG), SUV

Messages Page 2 of 2

#5 of 14 Grade logic control? by dtstof

Sep 14, 2007 (7:49 pm)

Perhaps the grade logic control keeps it in a lower gear.

#6 of 14 Re: Grade logic control? [dtstof] by gc4auto

Sep 14, 2007 (11:30 pm)

Replying to: dtstof (Sep 14, 2007 7:49 pm)
maybe it's because the lower gears are made to put out more power slower speeds? for offroad stuff since this is a SUV?

#7 of 14 Re: 07 CRV resistance [gc4auto] by blueiedgod

Sep 15, 2007 (9:04 am)

Replying to: gc4auto (Sep 13, 2007 11:42 am)
I used to drive a toyo camry and even when i dont step on the gas it just sort of glides forever.. but our new '07 CRV seems like it has a lot of resistance to it. If i dont step on the gas it slows down almost to a halt. i'm not sure if this is a "problem".. but anyone else experiencing the same thing?
 
Read the OWNER's MANUAL, especially the part about "grade logic."
 
Hondamatic operates like a manual would. Instead of shifting into neutral when you coast, it keeps it in gear, or even downshifts, because it thinks you intend on slowing down when you take you foot off the accelerator.
 
Reading the manual (3-10X, or however many times it takes you to know it from cover to cover by heart) is probably the best investement you will make into keeping your Honda running forever.

#8 of 14 Re: 07 CRV resistance [blueiedgod] by gc4auto

Sep 15, 2007 (10:58 am)

Replying to: blueiedgod (Sep 15, 2007 9:04 am)
doesnt this "grade logic" work against MPG? Which is kind of the selling point for these small SUVs vs. the guzzlers. Maybe they should give you an option whether to apply this "grade logic" or not.
 
Tho i've seen it downshift going downhill and thought that was pretty cool.

#9 of 14 Re: 07 CRV resistance [gc4auto] by gc4auto

Sep 16, 2007 (8:45 pm)

Replying to: gc4auto (Sep 15, 2007 10:58 am)
i think grade logic only applies when cruise is on? thats the only time i've seen it work.. i always cancel cruise on a steep downhill so the car doesn't automatically downshift, this way i can get better MPG.

#10 of 14 I think it works all the time(grade logic) by dtstof

Sep 17, 2007 (6:29 am)

I think it also senses if you start to apply the brakes a little and shifts down. Try not applying any brakes and see if it stays in a higher gear.

#11 of 14 Re: 07 CRV resistance [gc4auto] by blueiedgod

Sep 17, 2007 (6:42 am)

Replying to: gc4auto (Sep 15, 2007 10:58 am)
doesnt this "grade logic" work against MPG? Which is kind of the selling point for these small SUVs vs. the guzzlers. Maybe they should give you an option whether to apply this "grade logic" or not.
  
Tho i've seen it downshift going downhill and thought that was pretty cool.
 
No it does not. Cruising in neutral uses more fuel than cruising in gear.
 
When you are in neutral, fuel system supplies more fuel to the engine to keep it idling to power the accessories attached to it.
 
Ehen you cruise in gear, the rolling of the vehicle provides the rotational power to the engine. And since the throttle plate is closed, the computer minimized fuel usage because it thinks that engine is turning too fast for the given position of the throttle plate.
 
If you want to experiment, shift into neutral when coasting and see what happens with the fuel economy. Don't rely on the instant fuel economy reading, as it will skyroket, since it is calculated based on engine RPM and speed, and not by the actual fuel usage.
 
I get lower overall fuel economy (less miles per given fill up) when I shift into neutral on downhills, but my MPG meater reads 250 mpg going downhill at 70 mph in neutral, but I drive stick, my transmission is designed to be shifted on the go (I still have to double clutch to go back to 5th from neutral at the bottom of the hills, to save the synchros). Automatic will probably fail prematurely if it is shifted back and forth, like a manual, unless it is designed for that.

#12 of 14 Re: 07 CRV resistance [blueiedgod] by tidester

Sep 17, 2007 (11:43 am)

Replying to: blueiedgod (Sep 17, 2007 6:42 am)
When you are in neutral, fuel system supplies more fuel to the engine to keep it idling to power the accessories attached to it.
 
Are you saying that power is cut off to the accessories when you cruise in gear?
 
tidester, host
SUVs and Smart Shopper

#13 of 14 Re: 07 CRV resistance [tidester] by blueiedgod

Sep 19, 2007 (6:54 am)

Replying to: tidester (Sep 17, 2007 11:43 am)
Are you saying that power is cut off to the accessories when you cruise in gear?
 
No, but the fuel injectors inject much less fuel into the engine when cruising in gear than if you were cruising in neutral.
 
It takes fuel to keep the engine turning (even it idle), but when the inertia of the vehicle is turning the engine, it uses less fuel.

#14 of 14 Re: 07 CRV resistance [blueiedgod] by steve_ HOST

Sep 19, 2007 (8:56 am)

Replying to: blueiedgod (Sep 19, 2007 6:54 am)
When I last visited this argument, there were plenty of cites given that say that no fuel is injected when coasting downhill in gear.
 
typesix, "Hybrid Tips Optimizing mileage" #305, 20 Sep 2005 8:24 am
 
sebring95, "VW Passat TDI" #891, 8 Aug 2005 9:58 am
 
steve_, "How it Works! Welcome to Auto 101" #246, 24 Aug 2006 11:09 am
 
If people want to revisit the issue, that last discussion would be a good place to do it in.

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