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Old 01-14-2013, 04:08 PM   #11 (permalink)
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Quote:
Originally Posted by mcrews View Post
So you said (if I understand) that when IN GEAR w/ENGINE ON, NO FUEL flows to the engine when coasting down.
And At NEUTRAL COASTING enough fuel flows to idle the engine.

Need some proof on that.

Because the spark would have to be turned off also. And I just cant see that happening.

That is technology that is VERY similar to "engine off" at lights like BMW is bragging about in their commercials on the 3 series
Yes, it is true!
...to an extent
...on some models
...sometimes

What Chisel was referring to, is DFCO (deceleration fuel cutoff.) some makes and models implement it into the ECU, and dependent upon certain situations, it can indeed save more fuel rather then coasting in neutral.

For example: my 2003 CR-V implements DFCO during pedal off coasting in 3rd & 4th gears down to about 35mph, by engaging the TCLU (IIRC) and then resuming a normal "in gear" coast from 34mph->0mph.

Furthermore, the DFCO works all the way down to ~22mph if I disable overdrive.

This feature is great when I am wanting to use the engine as a brake instead of wearing out the pads and rotors!... But only during deceleration (to stop lights, signs, traffic congestion, etc) or maintaining speeds down a hill without the need of the throttle...

But there are many instances where neutral coasting benefits me more (slight negative grades, idle at stop lights, accelerating via gravity down hills, etc...)

Researching your engine/trans combo and use of a scan/ultra gauge or torque app, will allow you to find these values and optimize your habits accordingly!

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Old 01-14-2013, 04:42 PM   #12 (permalink)
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Quote:
Originally Posted by mcrews View Post
Because the spark would have to be turned off also.
Why would the spark have to be turned off? A spark with no fuel is just a spark and no combustion.

I believe this is also why carburated cars tend to backfire more often during deceleration because the fuel is still being supplied, but not being fully used.
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Old 01-15-2013, 04:24 PM   #13 (permalink)
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I won't EOC an auto for a few reasons. First. it may or may not damage the tranny, so, just not worth the small fuel savings. Second is for safety. This applies particularly when in traffic. With a manual, you have an instant means of spinning up the engine, even if it doesn't start, to regain power steering/brakes. With an auto, there is a delay and what the vehicles doesn't want to restart?
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Old 01-16-2013, 02:32 PM   #14 (permalink)
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Also, all your powered systems will be unavailable with the engine off, ie. power steering, power brakes, and any other computer controlled safety systems. Not safe or smart to coast with the engine off in any circumstance.
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Old 01-16-2013, 07:17 PM   #15 (permalink)
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Not everyone has PS, PB, ABS and an Auto. They only loose one option, the ability to accelerate out of a situation with out a restart.
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Old 01-17-2013, 12:07 PM   #16 (permalink)
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What I am saying is that the majority of current vehicles will have at least some systems controlled by the computer. Also, I believe that some SRS systems (air bags) will not deploy if the car is switched off, but that also depends on the car.

Basically, why would you risk your safety for the sake of saving a few pennies?
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Old 01-17-2013, 12:32 PM   #17 (permalink)
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Quote:
Originally Posted by Chisel86 View Post
What I am saying is that the majority of current vehicles will have at least some systems controlled by the computer. Also, I believe that some SRS systems (air bags) will not deploy if the car is switched off, but that also depends on the car.

Basically, why would you risk your safety for the sake of saving a few pennies?
That's why most users have a kill switch so the key can stay in the on position. I understand the safety aspect, and I would never eoc in heavy traffic, but on the highway and interstate, (around here), its perfectly safe.

I currently have an auto and I do neutral coast in a few spots of my commute.
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Old 01-17-2013, 02:35 PM   #18 (permalink)
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Quote:
Originally Posted by ksa8907 View Post
That's why most users have a kill switch so the key can stay in the on position. I understand the safety aspect, and I would never eoc in heavy traffic, but on the highway and interstate, (around here), its perfectly safe.

I currently have an auto and I do neutral coast in a few spots of my commute.
+1

selective EOCing a manual trans is safe and can save more than a few pennies.

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