EOC (keep in neutral or 5th gear?) - Fuel Economy, Hypermiling, EcoModding News and Forum

Pillzilla · 03-13-2008, 11:23 AM

When engine is off? Will keeping it in gear while engine is off hurt tranny?

I have got the hang of the ENGINE OFF Cruise now. PRetty sweet technique when rolling hills are involved.

Here is my procedure...let me know if I am doing anything wrong.

Get car going about 50-55mph just b4 reaching crest of hill, shift to neutral, turn key back one click(engine dies), dont touch brakes, coast with engine off for as far as possible until speed get to about 30MPH, push in clutch, shift to 5th, turn key back on, let clutch out, engine is on again and off I go.

Is this correct? Seems to be with other conversations I have read.

My only question is do I have to put car in neutral while coasting or can i leave it in 5th gear while engine is off?

Daox · 03-13-2008, 11:30 AM

Ehh... I see at least one thing wrong. With your key in the off position, your airbags are not active (or so I have heard). So, here is my procedure.

1) Accelerate to max speed at approx 75% throttle
2) Clutch in
3) Key off (one click back)
4) Key on (one click forward)
5) Shift to neutral (not always)
6) Coast to mininum speed
7) Bump start vehicle
8) Rev match and go to step 1

If I know my coasts are going to be longer I pop it into neutral. If I'm going up a hill and I kill the engine I usually leave it in gear and keep the clutch in since my coast will be shorter.

Pillzilla · 03-13-2008, 11:33 AM

so all i am doing wrong is not putting the key back to start position when coasting.....I thought I read that that was hard on the battery? thanks for the input!

NoCO2 · 03-13-2008, 01:56 PM

it can be harder on the battery if you are running a lot of electronics, like fans, that are only active when the key is in the start position rather then off. However, if you turn those things off the extra draw from the battery will be minimal.

boxchain · 03-13-2008, 04:50 PM

Quote:

Originally Posted by Pillzilla

so all i am doing wrong is not putting the key back to start position when coasting.....I thought I read that that was hard on the battery? thanks for the input!

Correct. On my car I don't even fully turn the key into the ACC position (not start!), I just back it 1/2 turn just enough to let the engine die, then pop it back into RUN. That lets the gauges work, and I can bump start at any time. Might use a little power (esp with the lights on) but I think it's negligible.

I also shift into neutral without using the clutch, push/pull on the shifter while you lift off of the throttle. I often shift by rev matching, but that's another topic altogether.

RH77 · 03-13-2008, 05:27 PM

Engine-off Coasting in 5th will hold you back more than Neutral due to compression of the engine. Neutral removes the resistance of turning engine parts and accessories.

As far as battery life is concerned, I think of that as a negligible effect of this technique. I've done a moderate amount of EOC'ing (with headlights always on: day or night for safety) on a 6-year-old battery, in an automatic.

In the Summers, I also have the blower running to draw air into the cabin as opposed to creating drag with windows down. So far it has outlasted my expectations -- but I expect it to go any day (I've said that for more than a year -- knock on wood).

This is all with an automatic. I have to rely on the battery and starter to get going again. I've tried the engine-off in Drive technique and successfully restarted with key-on, but the torque converter has to be locked -- and I'm not sure of the effects on the transmission with such practices.

There's a big, re-chargeable battery under the hood. I say, use it!

RH77

Gone4 · 03-13-2008, 06:24 PM

Quote:

Originally Posted by RH77

Engine-off Coasting in 5th will hold you back more than Neutral due to compression of the engine. Neutral removes the resistance of turning engine parts and accessories.

As far as battery life is concerned, I think of that as a negligible effect of this technique. I've done a moderate amount of EOC'ing (with headlights always on: day or night for safety) on a 6-year-old battery, in an automatic.

In the Summers, I also have the blower running to draw air into the cabin as opposed to creating drag with windows down. So far it has outlasted my expectations -- but I expect it to go any day (I've said that for more than a year -- knock on wood).

This is all with an automatic. I have to rely on the battery and starter to get going again. I've tried the engine-off in Drive technique and successfully restarted with key-on, but the torque converter has to be locked -- and I'm not sure of the effects on the transmission with such practices.

There's a big, re-chargeable battery under the hood. I say, use it!

RH77

I tried this in an automatic focus and I heard a decently loud bump. Is this safe to do in an auto? I want to try in the corolla, which is an auto, but I've been a bit scared. The corolla is a decade older too, if that makes a difference.

RH77 · 03-13-2008, 06:40 PM

Quote:

Originally Posted by GenKreton

I tried this in an automatic focus and I heard a decently loud bump. Is this safe to do in an auto? I want to try in the corolla, which is an auto, but I've been a bit scared. The corolla is a decade older too, if that makes a difference.

Good question. Honestly, I don't know.

If you're refering to the "kill the engine in Drive" procedure, I would guess that it is not healthy for an automatic. From the recent info that I've heard, there hasn't been any info to support it.

As far as Neutral, EOC, I'd be bold enough to say maybe

If your vehicle is safe to engine-off tow in Neutral with the drive wheels turning (per the manual) then I'd say "probably, yes".

Mine doesn't recommend such a practice, but it has been widely debated for and against. I've been EOC-ing for about 2-years (moderately) without consequence on a transmission with 133K miles (probably 30K miles of that). I did tighten the throttle cable to the transmission, which also tightens shifts to reduce slippage from "factory comfy-shifts" and to engage the TC at the minimum allowed speed per the Transmission Control Unit. When warm, it will lug the engine at 35 mph in top gear / TC engaged. Shifts are abrupt, but I'm told that's better than slippage.

Plan: It's time to change the transmission fluid, so I have some Synthetic ATF that I need to get in there -- just finding the time...

RH77

jazzie604 · 03-13-2008, 10:00 PM

almost all automatics require the engine to be running when the wheels are turning, because there is nothing pumping fluid through the system. Ask someone who has an RV and tows a car, it only takes 1 fried tranny to learn that lesson. A manual trans is designed to pickup and fling fluid whenever the axles are turning, so thats not a problem.

You will be less likely to cause problems by shifting into neutral when you want to coast (leaving the engine running) and then blip the throttle as you shift back into drive so that you dont shock the trans through the torque converter.
If you really need to EOC, find that $500 beater that is already a manual trans. Then you have no excuse not to gut it and modify it like basjoo did

Ryland · 03-13-2008, 10:49 PM

I keep my car in gear, and turn the key back to run as well, this keeps my odometer rolling, speedometer working, and alows me to simply let out on the clutch to keep my speed up as I coast up hills, this also prevents me from trying to bump start the engine with the key turned off...
Also when I took my drivers test years ago, they told me never to coast in neutral, but instead to simply use the clutch, apparently they felt it was safer.