engine off and coast question

[paintme205]

If you figure a 5-7 second break even point, then it is worthwhile. I gain 5-10 MPG on the highway doing P&G with EOC. I gain 4 in the city if I EOC once or twice a trip. Usually just to my house (about a mile) and to my parking spot at school (1/4 mile). So to me, it's worth it. With an auto trans, you need to make sure it is safe to EOC before you do it. Forget the starter, worry about your trans.

[PaleMelanesian]

The Fit auto is flat towable / EOC-able under the conditions of "less than 35 mph and less than 50 miles", just like most Hondas. Since you won't be EOC'ing for anything close to 50 miles, you can fudge the 35 mph limit a fair bit. Go for it.

I'd do a bit less EOC in an auto than with my manual, because of the power drain for restarting. These cars have a weak electrical system. It's perfectly fine for "normal" use, but what we're doing here is not normal. I plug mine in to charge about once a week in summer and every night in winter (more headlight use).

Do you have a gauge? Watch voltage closely.

As for the starter, I've replaced the one in my wife's Odyssey twice in 120k miles. She's not a hypermiler. I sold my old Civic with 200k miles and the original starter. I conclude that manufacturing quality matters more than our extra usage.

My rule of thumb is about 10 seconds. Any longer than that and I shut it off.

[bestclimb]

Originally Posted by parallelevan

I have an 07 honda fit new to me. Since I found this site I've herd of this alot please elaborate.
How long does the engine have to be off and started back up to benefit over neutral idiling?
How viable is this technique saving gas over wearing out my electrical system. (At so can't gear start)

When I had my MPGuino, idle was .25gph once warmed and .35-.40gph just after starting for I forget how long now. At the time though I measured it with the second hand on my watch and did the math. It worked out to shutting down broke even then payed for it self after a stop of about 5 to 8 seconds or longer. This was in a 95 honda civic. Other cars I have measured (with an ultra gauge so by necessity newer than 96 and fuel injected) have given similar proportions so the pay off shut down time is about the same.

[parallelevan]

Update: since my wife drives the car % 90 of the time. She turned the key off and didn't turn it back once engine died slight turn in the road and the steering locked and she panicked and I learned the abs do sent work with engine off either so 4 tires with a flat spot later I'll let her drive with what's she's comfortable and I'll do it when I can

[jedi_sol]

From the 100+ hypermiling tips:

55) Engine off coasting
Engine-off coasting (EOC) is one of the largest contributors to increased efficiency of hybrid vehicles, many of which automatically shut down the engine when the accelerator is released and the vehicle is coasting.

EOC can be accomplished in non-hybrids as well simply by shifting to neutral and switching the key from "Run" to "Acc" (being careful not to switch to "Off" and cause the steering to lock). As soon as the engine stops, return the key to the "Run" position or else you will be in danger of locking out your steering and crashing. Also be careful to not steer at all while the key is off to prevent a lock up.

This technique is best suited to cars with manual steering and manual transmissions. (Dramatically increased steering effort may be required in some cars with power assist. Also, most vehicles with automatic transmissions are not designed to travel with the engine shut off; the transmission may be damaged).

In non-hybrids, EOC is considered an advanced technique and should not be attempted until the skill developed away from traffic. In addition, coasting with the engine off is illegal in some areas.

The best way to EOC is with a kill switch that shuts off the engine without removing the key, thereby eliminating the dangers of locking the steering wheel.

I hope your wife does not ban you from ecomodding

[Fat Charlie]

Too little information can be a dangerous thing. EOC isn't entry level stuff.

[parallelevan]

I'm not banned as of yet but it all could have Ben worse. O well ill keep doing my thing and we shall stick to hypermilling for beginners with her

[davelobi]

Maybe since you are running with an automatic transmission you should look into the "deceleration fuel cut off" method of saving a little fuel. Better known here as DFCO. Search on the site for lots of information.
Here is some info I posted a while ago..
http://ecomodder.com/forum/showthrea...rta-27051.html

While in dfco mode you are using exactly the same amount of gas as having the engine shut off.. none. The coast will not be as long however because your drivetrain is slowing you down more.

[PaleMelanesian]

I disagree. I find the engine braking from DFCO costs more than neutral idling. It eats up too much momentum and you burn fuel to regain that. This is on an automatic, too - my family car is an Odyssey. If you're not going to EOC, neutral idling is the next best. Shift to Drive when you need power, neutral at all other times.

[davelobi]

Originally Posted by PaleMelanesian

I disagree. I find the engine braking from DFCO costs more than neutral idling. It eats up too much momentum and you burn fuel to regain that. This is on an automatic, too - my family car is an Odyssey. If you're not going to EOC, neutral idling is the next best. Shift to Drive when you need power, neutral at all other times.

How can you disagree with using zero fuel? If you understand dfco you know that the ecu actually stops sending pulses from the injector drivers, shutting them off. Zero fuel is being used at this time while at idle the injectors are still squirting gas. As far as losing momentum, we have to do that often during a commute for red lights, stop signs, and to slow down to make a turn. I'll let off the gas and coast down to an acceptable speed to make a turn and use no gas while slowing down. If my coast is going to be long enough then I will eoc and enjoy the longer coast but you would be surprised how far you can coast while leaving it in gear as well. DFCO is programmed into the engines computer for a good reason, it works well.
"Shift to Drive when you need power, neutral at all other times" .. Do you bump into neutral and back to drive constantly for P&G? I constantly go in and out of dfco while driving effectively increasing my mileage by a respectable amount. In neutral while slowing down to make a turn is wasting gas that could be saved by having the computer shut the fuel injectors off.

Here is an old post from when I was learning the dfco parameters in my car..
http://ecomodder.com/forum/showthrea...rta-27051.html
My chassis ear made it very easy to know when fuel injectors were pumping gas or shut off. I know it isn't something everyone has access to but it does it anyway. Might as well use it. If anyone local wants to try out my listening device you are welcome to it.