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Old 10-08-2014, 12:40 PM   #1 (permalink)
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neutral or not to neutral

Thanks to this site I've been learning to go into neutral down hills to gain accelration.

My question is simply, should I be put my vehicle into neutral while coasting to stops etc?

To my understanding it will be beneficial to a small amount of mpg gain (I drive a 2014 vehicle). On another truck forum I was told when doing so it locks up the torque converter, thus not saving me any gas at all.

Should I be neutral coasting or not? Opinions?

Thanks again for a great forum and good tips.

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Old 10-08-2014, 02:31 PM   #2 (permalink)
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When coasting to stops, leaving it in gear will increase your fuel economy.

The reason is your engine's EFI computer will detect the engine overspeeding the throttle input - that is, your engine will be revving faster than the throttle setting would indicate that it should be. Detecting this, the EFI will reduce the amount of fuel injected into the cylinders at each cycle in an effort to reduce what is perceived to be a call for reduced engine speed. On many vehicles, the resulting injector duty cycle can drop right down to 0 - no fuel gets injected at all.

It doesn't matter if your torque converter is locked or not, at this point we're only talking about what the engine is doing.

It also reduces wear on the brakes. There will be some debate, and good points to be made, that transmissions aren't for braking while brakes ARE, and while brake jobs aren't cheap they're still a hell of a lot cheaper than transmission repairs. As far as that goes, use your own judgment. My truck has 200,000 miles and I coast in gear, engine off, to stops. I only replaced the clutch this spring and am still on the original gears. How much damage that kind of use might do I cannot say but I think some of the alarmists are a bit overwrought.

NOTE: do NOT turn your engine off for coasting. You have an auto, engine-off coasting can do terrible things. Exception: if your vehicle is approved for flat towing (for instance, behind an RV with all four wheels on the ground all the time) then it's probably OK to turn your engine off, assuming you still have adequate steering and brake control. Caveat emptor!

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Old 10-08-2014, 09:10 PM   #3 (permalink)
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The answer isn't that simple. My 98 dodge will almost never go into DFCO without downshifting or going really really fast , my Impala and pervious Malibu won't go into DFCO without downshifting out of OD, they unlock the torque convertor and coast almost as good in OD as N(haven't driven 2010 cobalt to know how it works). Want engine braking need to shift to D.

If Neutral coasting extends you coast distance considerably it's most often better than using DFCO unless going downhill where you need to limit top speed or stop at the bottom.
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Old 10-08-2014, 10:02 PM   #4 (permalink)
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You need to get a scangauge or ultragauge or the android app torque.
Every car is different my KIA doesn't have dfco and is at 3k rpms at 65mph. It is much better for me to put it in neutral and Eoc.

The work van is the opposite and has very aggressive dfco that I try to use as much as possible. It is automatic and a slow auto at that.

I learned all of that from torque app and scangauge and driving many miles.


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