engine off and coast question
 

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:confused: to benefit over neutral idiling?
How viable is this technique saving gas over wearing out my electrical system. (At so can't gear start)

The gains are there, they are compounded after dozens and dozens of engine off coasting , you will save a negligible amount but it will add up and you can hypermile with it to get more gains. The technique defiantly works it`s just to much work for me..


I don't engine off coast because I don`t need to to get great gas mileage , I normally coast with engine On unless its a extremely long coast , like a 5 or 10km , I have a mountain Pass that I coast home from for over 10kms a couple times a month.

5+% possibly?

Agressive EOC and engine off at lights gave me massive gains on my MB100, over 15%.

BMW and Ford have auto stop start systems and quote 3 and 5 seconds as the break even period. I have auto stop start on my Fiat :) I won't buy another new car without it.

Most people will agree that starting a hot engine takes very little power and places minimal stress on the starting system, though it may be a good idea to add a solar panel to keep the battery fresh (which is what I did).

I bump started where possible though.

I just randomly did a google search for the cost of a 2007 Honda fit starter

it ranges between $50 (ebay) - $172 (remanufactured oem)

I've saved over $600 in fuel costs PER CAR / PER YEAR by hypermiling/ecomodding both my old Honda Del sol and Subaru wrx sti

Can your vehicle be flat towed?

Is your Fit an automatic or manual transmission? If it's the latter, then bump starting will save your starter. I would say 5 seconds is an absolute minimum. It would get too complicated to do it more often.

I would start EOC'ing at the *best* situations, and then add shorter times as you see fit. (No pun intended!)

He said AT.

If your vehicle can not be flat towed, I would not advise EOC.

I've been turning my engine off at stoplights in my truck for decades - literally decades. And now with the truck entering its 27th year, it's on its third starter. You might wear the starter a little faster than otherwise, but averaging nine years on one isn't bad either. And my truck's mileage is fantastic.

I would recommend shifting to neutral for coasts rather than coasting in gear. You would need to do some math to figure out where the break is, but I think the greater glide in neutral will more than offset the zero fuel use of the shorter glide with the tranny driving the engine. An engine control system will usually reduce the fuel feed to the engine in such a state to zero, but the engine drag pulls the vehicle speed down too quickly. The engine doesn't pull much gas just to idle, so the longer glide can deliver better results. Again: testing and math to know where the better results lie.

I've heard a break even point of 7 seconds... via this site. Make doubly sure your vehicle can be flat towed before you try this, and always do it in neutral only. Automatic transmissions are not generally made for that kind of stuff, whereas manuals have no problem (but also must be in neutral).

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.

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.

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.

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

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 :)

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

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

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.

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.

Oh I understand DFCO very well. It uses zero fuel. But it's not always the best approach to making mpg. It also eats up a lot of momentum. I burned fuel to make that momentum. I want it to take me as far as it can. DFCO adds an unacceptable amount of drag.

Yes, I'm in and out of N and D all the time. Back and forth and back and forth. At least on a Honda automatic (my personal experience), that's the way to get the best mileage.

Yes, while slowing for a turn or a stop, DFCO is useful as you're slowing AND not using gas. But you could start neutral coasting sooner and you don't have excess speed to burn off. You spent unnecessary fuel to be in that position, so DFCO is only a least-bad solution. Better to not need any braking at all.

Pale, please don't be offended, I didn't mean that to sound like it did I guess.
Your longevity on the site and impressive mileage numbers show that you know what you are doing. I wanted to elaborate on dfco for others who don't know about it. It isn't as obvious as other methods.
neutral coasting vs eoc vs dfco vs driving habits = why they made apples and oranges. Something for everyone.

What's great about some cars is the transmission is programmed to go into a pseudo-neutral coast just by lifting off the gas pedal. A lot of GM models do this that I know of. On the other hand, Honda's programming puts it into pretty harsh engine braking and DFCO every time you lift off the gas. I'm fighting that programming whenever I drive it, so DFCO is kind of my enemy.

Another thing that works on Honda A/Ts in my experience is if the transmission has decided to use a higher gear than necessary for whatever reason and doesn't shift down, going to neutral and then back will make it select a higher gear.

Oh yes. That's a great trick. Mine won't use 5th gear until 45 mph, but will then hold it down to 38 once it's in 5th. A quick D-N-D shift at 40 mph and it drops right in.

What about the brake booster when the engine is off?

Also, does an engine with a manual transmission use any fuel if coasting down a hill with 0 throttle, being pulled by gravity above idle RPM?

Brake booster will not be supplied with vacuum used to assist with your power brakes when the engine is off. You will have one or two pushes of the brake pedal with vacuum assist from what was in the booster and that is it. After that it will be very hard to push on your brakes but they will still work.

Your question about coasting down a hill (I assume you meant engine on and left in gear) with zero throttle is a method I use a lot. Go back a page and find my post (#18?) that has a link to DFCO. EOC will coast further but DFCO also uses zero fuel while in effect.

thank you!

Depends
 

If yours is a fuel injected engine, the computer might recognize the loading paradigm and provide no fuel while the engine is being driven by the tranny. Certainly a carbureted engine will continue to burn fuel, but only at a slightly above idle rate as the increased vacuum pulls a little extra fuel through the jet.

As for the brake booster, if you're still in gear but letting the car pull the engine, you're getting a strong vacuum into your reservoir the whole time (unless it's a diesel, YMMV). And even if you're coasting in neutral you should still have enough vacuum in your reservoir for a couple of stops.

If not, consider building or buying a supplemental reservoir to tuck into one of the unused spaces of your car, to provide backup.

thanks! excuse me if this is commonly searchable on here but since we're here... for those that shut of their engine and coast in neutral, then restart their engine, is there advanced wear on the engine upon restart due to low oil pressure, and do you use a starter or can you bump the engine with the clutch at speed?
How much mpg increase can you expect to gain? Sounds risky but worth it if you know what you're doing...:)

I heard (not really) that God does not remove from ones allotted lifespan time spent hypermileing. Maybe the same goes for your engine.

Wait, maybe that was for time spent fishing.

Concerning the brake booster while the engine is off:

Although you'll only get one or two pumps of the brake pedal before the booster freezes up, you can make the pumps last as long as you want. I've learned to apply the brake gently with one long gentle pump while I EOC up to a long light, and then instead of pumping it again, just apply more pressure. I've never ran out of pedal so far using that technique.
I also brake early and time the lights, so most of the time I'm able to bump start instead of actually stopping.
FYI: Keying on while the booster is frozen up will immediately drop the brake pedal to the floor, so you'll need one pump to get brake pedal back! Don't wait until the last second to key back on if the booster freezes, do it early.

Haha, good tips thanks! I'll be looking more into the wear and tear on syncros, engines and clutch parts with different techniques. I think if I can manage above 40mpg without using hypermiling techniques I'll be plenty happy. :turtle:

Lol, figit, that's what I thought too . . . .

I drove Black Widow for a year and a half bragging to everybody that I was averaging 43 mpg. Then while I was looking for a Festiva forum, I stumbled across ecomodders, where a couple of guys were getting over 10 mpg better then me in the same car. The rest is history!

You're fooling yourself if you think you'll be happy with a milestone like 40 mpg, when there are more milestone just over the horizon, like 45, and 50, and 55, and 60, and . . . . . . . . ..

I currently burn fossil fuel at a rate of about one gallon per 18 miles. Not fooling myself here! My actual goal is 50mpg but I don't want to get ahead of myself until I learn what the HX is capable of, and how much wear various techniques cause. I won't hypermile for 50mpg if that costs me 10k less miles on my clutch, worn main bearings or a transmission rebuild to fix worn syncros, the cost to fix premature wear on otherwise durable parts would make hypermiling completely mute.

I'm thinking good tires, momentum-aware driving, and mild aerodynamic improvements to the car would help a bit, too.

I'm at a crossroads where I need a new car, because fixing my current one is prohibitively expensive as a daily driver. So, I'm putting it to pasture until I can turn it into a track car, and finding a new car. While I'm at it, my goal is to not spend exorbitant amounts of money for a new hybrid, but double or triple my current MPG. :p:p

So for me, 40mpg is a realistic starting point until I learn more and get accustomed to eco-modding. I'm used to performance modding, so it's a nice new challenge to ponder!

If you know how to rev-match, then you won't wear out your sychros and clutch any faster than normal driving.

I hypermiled my honda del sol for 180,000 with no transmission problems at all when i came around to selling it :)

what about bump-starting at speed after coasting with the engine off?

Sounds good though. :)

Seeing how you drive a STI how I'm wondering if I should even bother to hypermile... did you hypermile to save cash for a better car like I'm planning to do? ;)

when im driving at speed, i just barely release the clutch until i feel it engage, then the engine fires on. It ends up being, what, 100rpm?

Once the engine fires on, you press the clutch right away, then you just rev match back into 5th or 6th gear. Thus preventing premature wear.

Yes, i hypermiled my old Del sol for 5 years (greatly reducing my gas expenses), which eventually allowed me to save up enough money to buy my dream car - sti. :)

Oh cool :) thanks for the tips! :D:D
I'll be saving for another supra probably, and you've convinced me with the further explanation of ~100rpm starts that it's easy to start at speed. I'm not sure why I was worried about premature wear on the engine when the clutch and starter would start the engine the same exact way...lol. I was concerned about clutch wear too, but it doesn't seem to be an issue if the engine starts up that easy. I've only ever push started my current supra from a slow roll, so I guess in my car I'll install a kill switch on the shifter and go for it! :) :turtle: I'm excited, I just need to find the right car now.

bump starting really depends on the speed at which your driving.

if im going 20mph...then i'll bump start in 4th
if im going 40mph...then i'll bump start in 5th
if im going 50+mph...then i'll bump start in 6th

Anything slower than 20mph, then i'll just use the key/starter because, like you said, i dont want to prematurely wear the clutch because bump starting at such a slow speed causes the car to jerk a lot.

Therefore, engine off coasting is mostly beneficial at speeds faster than 25mph