Question about the math for EOC vs Coast?

[Xusn96]

Just to clarify, from your sig badge thing, I presume you are testing these options with an automatic transmission, correct? EOffC is something I have toyed with in my Taurus, but frankly with the column stalk shifter, i am burdened with the fear of bumping past N to R (*MENTALHORROR*), so I have just let that idea drift off. Additionally you're also placing a huge increase in the usage of your starter as the auto trans' obviously can't bump start.... Now for you with the tunnel stick you have a little finer control to avoid bumping into R so that works, but the starter wear question arises, as does the flywheel as mentioned by others.

[PaleMelanesian]

Doesn't your car have some kind of lockout that makes it hard to accidentally shift into R? My Odyssey does. You can push and pull the shifter between N, D, D3, and D2, but to go into R you have to pull toward you as you move it. My sister's Camry has a button you have to push.

[PaleMelanesian]

I estimate I spend about half my driving time EOC coasting. My commute takes 30 minutes, so 15 of that is coasting. My car idles at 0.22 gph. That's .055 gallons each way, or 0.11 per day, or 13 cents. Times 21 work days per month equals $2.73 / month, or $32 / year.

That's only counting commuting, not extra trips.

I spent $387 over the last year on gas, so EOC is saving me roughly 8% in fuel costs.

[awcook]

I wouldn't do EOffC in an automatic tranny. That will damage the transmission and put wear on the starter. In the owners manual for my Civic, it says that the transmission can only go 50 miles while being towed in N with engine off. So if you EOC 1 mile per commute trip, then you only have 25 days before the transmission starts having problems, according to the Manual.

I EOnC with my Civic at 10-45 MPH because it can coast really far at those speeds, and that is most of my commute to school (going home I take the freeway because there is no traffic and believe I get better mileage going that way).

[PaleMelanesian]

No no no. 50 miles at a time. if you need to go farther you have to start the engine and run it a bit and shift through the gear positions, to re-lubricate the transmission. Then it's good for another 50 miles.

1 mile is way below the threshold, at least on Hondas specified like yours. My Odyssey is the same.

[awcook]

Oh, thank you PaleMelanesian, I had no idea. Then I guess the only wear on the car will be the starter for EOCing in an auto.

[songman]

Originally Posted by moonmonkey

you also use a little gas on restart

Not if he clutch bump starts.

[bentring]

Speaking to those of you who have bump started for thousands of miles, does it seems not to affect the durability of the transmission? My owners manual specifically states not to push start it, and it's been years since I've kept up with auto tech so I didn't know if anything in manuals has changed to make it a bad idea, or if they were just covering liabilities.

[oldtamiyaphile]

When bump starting a cold engine unburnt fuel may enter the cat, which would shorten it's life. It shouldn't apply to hot engines. Chances are if you EOC your cat isn't getting up to temps anyway, though I don't think anyone here has actually had a cat failure from EOCing.

[oldtamiyaphile]

Most cars will go open loop after you key off and restart.

This means the next pulse happens in open loop. Since the car's already in open loop/ enrichment should I just floor it? This method means I only need to pulse for maybe 5 seconds.

The alternative is to drive at low load while in open loop, however, it takes about ten seconds to switch to closed loop, so that means 10 seconds of at say 40% load followed buy the real pulse of 100% load once it goes closed loop.

I think the first method is actually more effective. I don't know how long my cat will last though as I've already got a cat low temp code at ~3000miles from new. I assume running in open loop all the time won't help it?