Confucius say EOC inevitable
 

Confucius say, man who use divine bovine for username, cannot resist EOC and bump start.

I've decided to go ahead and enjoy. I get a few >1 mile glides daily, might as well not idle. I'm going to try to wait because I have a baseline and I want to test aero mods while I've got a good baseline.

People who EOC: How long should your glide prediction be before you'll decide to EOC?

I do it when I can coast 1/4 mile or more. I'll do it on shorter hills if there is a traffic light at the bottom and the light is red.

I do it at every chance i get. I don't try to guess how far i can get. Going home i can eoc for 1 mile making 1 long run(40mph)right turn(25 mph) left turn(15mph) to a stop sign. On the freeway i went 1 1/2 miles, but short, medium, or long is ok with me. The best though is eoc with drafting!

I keep forgetting to look at the odometer, so when I come across an eoc opporitunity I like to count. I found it's worthwhile if I can coast for 20 seconds, which is also about 1/4 mile at freeway speeds. Coasting 1/4 mile at city speeds takes longer, but it's still worth it if the engine can remain off for 20 seconds or more.

I remember reading a thread that discussed how much fuel is used when starting an engine vs. how much is used to keep it idling, and the research showed the break even point was 7 seconds. In other words, idling for 7 seconds uses the same ammount of fuel as key starting the motor. Of course this varies from car to car, with older cars being worse. EOC for 7 seconds is the break even point, anything longer saves gas.

I want to EOC :( stupid grand prix auto that can't.... although, I did draft a VW this afternoon on my road bicycle. I managed at least 35mph, possibly 40mph for a short stretch. I know this cause the limit is 45mph, and cars weren't passing me very fast.

need to update my gaslog. Managed about 1mpg better with all intown driving by using neutral glides everywhere. not alot, but its something.

Actually, since I'm bump-starting, I suspect that it doesn't use more gas like electric starting does. Would that be correct?

I agree with you- if the key is just in the on position when you bump start, the ECU shouldn't use the extra rich fuel map that is triggered by the key going to the "start" position.

Good point. It doesn't seem right that you would have to glide for 7+ seconds to see a gain. Any time with the engine off is a gain, and bump starting doesn't seem like it would use any excess fuel.

for me it is based on speed. obviously on backroads it is shorter than on the highway, except for when ending a trip. that's when i try to get a long final coast using little or no brake at the end.

i try to get up to at least 35mph to do EOC since a 25mph bump start in 4th gear is the smoothest for me.

Key start vs. bump start? Hmmmm....
Both have advantages and disadvantages. Sorry for the poor organisation, I'm just going to blurt out my thoughts.
Bump start doesn't use startup enrichment, although it does use accelleration enrichment since the engine gains revs quickly. Key start uses startup enrichment, and it adds electrical load on the battery that needs to be replentished by the alternator. A big downside to bump starting is that it steals momentum from the car, so the car will slow down a little. I figure it's better to rob the momentum directly from the car rather than involve the electrical system which has more efficiency losses.

When I bump start I keep forgetting to open the throttle right away, so I get approximately 1/2 seconds worth of engine braking which doesn't help FE. OTOH it's not smooth when the engine kicks in with an open throttle.
Overall,I bump start because it conserves physical energy (I'm lazy!)

I think that DFCO is the best option in most situations. If you have a long stretch of road with no cars, pedestrians, or animals; and DFCO causes too much engine braking for you to make it, then I could understand. But I think it's just a matter of time until some kid runs out in front of someone who is going to wish they had their power brakes.

All other things being equal, that would be an interesting question, and I'm pretty sure I know the answer. To electric start, you have to convert rotational motion into electrical energy, store it, then convert it back. To bump start, you use raw rotational energy. Converting it twice and storing it in-between is bound to be more wasteful.

suspendedhatch, about braking: My power brakes and steering work fine with the engine off, though the brakes run out of stored pressure after 3 or 4 uses and then I have to put part of my 220 pound body into it -- and that's still enough for decent braking. However, I've tested quite thoroughly, and in my car Pulse & DFCO is the least efficient option, even worse than just cruising normally. Pulse & Glide with the engine on and transmission in neutral saves lots of gas.

Those are my measured observations, not theories. Pulse & DFCO just doesn't work, at least in my VW.

Anyway, the places where I would EOC do not have children, or pets, or people, or other cars; I drive some nice empty roads through the woods on the way to work:
https://lh4.ggpht.com/ronanian/SDleut...6/IMG_0908.JPG

Yes, I take a chance of hitting a deer/coyote/fox, but that is my own risk and I'm happy to take it.

I eoc if it's going to be > about 10 seconds. I would probably go shorter, but my scangauge takes a couple seconds to come back online and the reported numbers are inaccurate if I do it too quickly.

I bump-start any time unless I'm actually stopped. A quick up-down pulse in 5th to fire the engine, then choose the gear and let it out again. There's little-to-no jolt or momentum lost that way.

OK, on the question of the difference in enrichment for warm electric start vs. warm bump start: I hooked up the meter and found out for sure. Bump start definitely uses less fuel than electric start.