Bump.

With all the new influx of people to GasSavers, thought I'd bring this back to the top.

Interesting read. I'd like to point out something that should be mentioned any time someone speaks of coasting. The transmission needs to be mentioned, manual or auto, and it needs to be mentioned that an auto will be toasted by engine off coasting. It will happen fast enough that car makers put it in their manuals that being towed in neutral, engine off, with the drive wheels on the ground will void the warranty. When the engine isn't running, neither is the tranny pump, so the guts of the trans are moving, but not being lubricated. The effect is the same as running your engine with no oil. Since a lot of new people might be lurking and may not know this, this should be noted in every new post string concerning coasting with the engine off. Manual transmissions are usually bath lubed, meaning the gears are down in the oil, so they get lubed whether the engine is running or not.

Second, on the braking issue. The easiest, cheapest way to address this would be to use a vacuum can with a one way check valve. High performance cars with lopey cams don't build enough vacuum to operate power brakes and stuff, so these cars usually use a simple vacuum can to provide vacuum for the brakes. They are available from Summit Racing for around 50 bucks, and will not interfere with braking operation when the engine is running normally. A vacuum can should provide enough vacuum to operate the brakes 4-6 times engine off before the vacuum is depleted, so long as you have that one way check valve installed. Some cans also have a port for a vacuum gauge on them, so you could install a gauge to tell you when you need to crank the engine to rebuild brake vacuum. You don't have to buy that expensive can though, you can make one so long as you can come up with a sealed cannister with the proper fittings that will stand up to a vacuum.

Slight but important correction to that: IF your manual says don't flat tow, don't EOC. If it says flat towing is ok, EOC'ing is perfectly safe to the driveline.

In response to DRW / rh77 above, I will clarify what they are talking about :) If you have power steering, and you restart the engine, then the power steering will suddenly come back!

The danger is that if you are hanging on to one side of the wheel going around a corner, when the power steering comes on, then the force you are applying will mean you suddenly turn a lot more sharply, lost control, and crash!

The solution is to restart when not turning, or, 'brace' your arm against e.g. the door, so that it won't move when the power steering returns.

I'm one of the biggest eoc'ers/fas'ers around. Its nothing for me to bust off into a eoc.

I sure wish the noobs would get the basics down first. Im seeing away to many noobs going right into the advanced tricks of the trade.

psy

Great thread I have enjoyed it! Using your park brake is not always a great idea. If anyone is behind you, you have no brake lights! So if you do this in traffic it would be a good idea to install a switch in tandem with your brake switch. Also remember 2 other things. 1 if you have rear disc brakes alot of new cars have smaller linings for the park brake. why do I keep calling it a park brake instead of an emergency brake? Because they are built for parking not emergencies. Work in the industry gotta be LEGAL here. 2 if you own a car built after 05 make sure and check that you have brake lights with the key off. For years in the US it was a law that brake lights had to work at all times. Not with the global economy of things. At least for GM, can't speak for other models.
P.S. I love to coast too. 6 miles of my daily commute is coasting. Here in the flat lands one place to remember are freeway exits. They don't call them free for nothing.

Hey, how come no gas log on the Red jelly Bean?

My car stops fine without power assist. Just have to push HARD!

I actually just contacted Ron about this having seen it for myself (why is my mpg going down, the engine is off?) and let him know others were seeing it in their saturns.

It is apparently the saturn pcm publishing that info to the obd port. On the plus side it is putting out a bizzare "61RPM" signal too, so I asked ron if the gph could somehow be "zeroed out" in the scangauge for an obviously wrong rpm reading (i.e. less than 200RPM say).

skewbe -

Someday maybe we'll have programmable scangauges that we can "tune" to the whacky behavior of our PCM/ECUs

CarloSW2

My Cavalier has an automatic transmission, so I always coast in neutral with the engine on - uncalibrated ScanGuage II reporting 0.4 gph. I've got an ~ .2mi coast to my office at 25mph, so I shut the engine off the other day, just to see what the SG would read.

0 gph, 0rpm, 0tps, and 9999mpg. :)

Boy, that felt good. I wish I had a manual trannie, but I have to settle for 150mpg with the engine running.

Thanks for bumpin' the thread, CO

Well, let's bump one more time, 9 months since last bump.

or make a pedal/ICE hybrid!

I think you can adjust your Scan Guage to read 0.0mpg if you set it to "hybrid"

I thinks it's the other way; not set for hybrid gives zero mpg and set on hybrid gives 9999mpg. If an ICE car is not set for hybrid the ScanGauge does not credit the miles while coasting with engine off ( thought the ignition switch still needs to be in the on position; just switch it off long enough to kill the engine and switch back on without bumping the starter.

If I cut my engine of I lose my steering. Will DFCO make up for your engine not being off?

You should only lose power assist. More effort will be needed to steer the vehicle, but not overly much if you are rolling at near highway speed. Vehicles with electric power steering could in theory retain power assist with the engine off and key in the on position, but that depends on how the manufacturer sets things up.

Another "warning": you will also lose the power brake assist after some number of brake applications with the engine off. Again, they will still work but just require a bit more muscle.

Not sure if it was said already, but for thoes who turn the engine off, what about brake boosters and power steering being disabled? Also what method do you use to restart the engine? Clutch? Ignition switch?

When I cut my engine off, I do so with the understanding I have one brake application. I have an automatic so I restart in neutral.I just do this when approaching a light and a 50% chance that I'm going to have to stop.

Try it on a back road or large parking lot late at night. Honestly, everyone should have some sort of understanding how their car will behave if their engine ever should happen to stall while driving.

Just get going at a speed you are comfortable with, put it in neutral and cut the ignition then turn the key back to run (so the steering wheel doesn't lock). Except for older Citroen's (which had a totally weird brake system), I am not aware of any designs that would render the controlls useless in the event of an engine stall (for obvious reasons!) but try this first in a safe location, just in case!

To get a feel for the brakes without power assist, you will need to tap the brake pedal a number of times after shutting the engine off in order to bleed off the reserve vacuum boost. The pedal should feel like a rock. Be prepared for the brakes to require a significantly higher force to work without power assist. The loss of power steering is immediate but the increase in effort while the car is moving is generally not as much as in the brakes. Steering will get harder at slower speeds though and can be rather difficult when stopped.

I have driven cars with the power steering and/or power brakes intentionally disabled at various times. It is entirely do-able if you are aware of what to expect from the controlls and drive appropriately. Of course, YMMV, be safe and do this entirely at your own risk.

Nice to see the same ol' crowd is still posting on here. :) I only read half this thread, but to me the salient point is what is the difference between EOC and engine on coasting. How much fuel would you use going down the hill with the engine on and coasting in neutral verse the engine on and engine breaking (which if I understand right, above a certain RPM, uses no fuel)

Also, I made a post awhile ago about what route would produce the best FE. I postulated two theories: one, where the route has a very steep incline and then a very gradual decline (my hypothesis is that this would be best for a one way trip (but terrible going back the same way) and that a slight incline up and a slight incline down would be best for a roundtrip route. Does anyone want to weigh in on this?

This is what I've always wanted :D Crank or some such. An extra pedal to push on while you're waiting in traffic or cruising down the highway.

Moved from top of thread
 

The single most important improvement to FE you can ever do. FREE.
Two days ago I drove 20 miles to the top of a mountain near me. I wanted to do a concrete test of the benefits of Engine Off Coasting in a manner that anyone can understand. I already know that this is the longest coast in my area.

My test would compare Engine Off Coasting in high gear with Engine Off Coasting in neutral. Engine on coasting can only be worse in each case.

Turned out to not be much of a test at first. In gear, car would not even roll downhill on a sizable grade. No problem with that in neutral.

So I decided on a running start from 55 MPH for each scenario. I would travel down the mountain till car speed slowed to 30 MPH, stop and note the miles travelled, immediately turn around and drive back up to the start.

1. Engine Off Coast in 5th gear. Car slowed immediately after engine was shut off. Fastest speed recorded with ScanGauge was 53 MPH. Average speed was 36 MPH. Distance travelled 5.1 miles, much of it near 30 MPH. Even so, no fuel was used. Turned around and drove back up mountain to start. At that point, SG current trip 47.2 MPG for 10.2 miles. This is a climb that would indicate about 25 MPG without the coast being involved.

2. Engine Off Coast in neutral. Car gained speed from the start. Fastest speed recorded 76 MPH with hitting the brakes twice to stay near 75 MPH. Average speed was 56 MPH. Distance travelled 8.7 miles. No fuel used.
Turned around, drove back to start. SG current trip 67.4 MPG for 17.4 miles.

This amounts to 70% more miles travelled and +20 MPG over the 17.4 miles.

I ran each test a second time and results were so close they don't bear repeating.

I attribute much of my FE success to this very thing. I honestly believe this is the single most important ingredient of my FE. And it's all FREE.

Moved from post #70 of this thread. 3/30/08
 

New coasting info. 3/15/07

I have had both my front fender skirts finished for a couple days. For the last 3 months I have been refining with left side only.

Link to front skirt project: https://www.gassavers.org/showthread.php?t=2173

Yesterday I drove the coasting route used in tests above. Coasting speeds were significantly higher at every point. Where I had braked twice before to stay close to 75 MPH, I had to brake 6 times yesterday.

When I reached the point where I had slowed to 30 MPH before, I was going 40 MPH yesterday. This extra 10 MPH allowed me to clear a rise at 32 MPH that I had never cleared in many tries at any speed. There was enough additional downgrade to coast another 3.8 miles till I slowed to 30 MPH.

This coast was 12.5 miles vs 8.7 in original test. These runs were Engine Off in neutral.

Reminder. Coast with Engine Off in 5th gear till slowing to 30 MPH in original test 5.1 miles. I did not repeat this run yesterday because of the obvious uselessness of doing so. Yesterday's coast was near 2.5 times as far.

Don't you think everyone should be Engine Off Neutral Coasting at every available opportunity? Even if you have to make your own opportunities.

Damage to Auto Transmission?
 

I've been warned not to EOC with an auto tranny unless the manual has no cautions about towing with the drive wheels on the ground. For example, my Mazda MPV manual says that if you have to tow with the drive wheels on the ground you must not exceed 35 mph and 35 miles. Something to do with lubrication.

I'm not a mechanic, but I know that the effect of EOC is the same as towing, it's just that gravity is moving the car instead of a tow truck.

Shouldn't there be a warning about this as a sticky note at the beginning of threads about EOC?

But at 60 mph with a larger ICE that gets .5 gallons per hour in idle, you're still getting 120 mpg at 60 mph, or 60 mpg at 30 mph. Beats my 22 mpg highway rating.

But then, if you're coasting really slow, like five mpg, you're only getting 10 mpg. I suppose if you're coming up to a long light, you could turn the engine off at 35 and EOC to the light and wait, and save more.

But how much abuse can a starter take? From a pure cost point of view, it might not be so great unless you reserve it for long waits.

I personally would not EOC with an automatic regardless of being able to tow with the drive wheels on the ground. As you pointed out, there's still significant benefit to pulse and glide with the engine idling and virtually no risk of transmission damage or increased starter wear.

My manual gearbox cars however rarely see additional starter use from EOC'ing, as I bump start 90% of the time as I near a stop unless I anticipate being stopped 30 seconds or more.

Bobsterz, your concerns are real and appropriate. Do not EOC with an automatic unless it says you're safe for full wheels-down towing. The transmission depends on the input shaft (the engine) to run its oil pump and keep it cool. If you tow at 35mph, it probably wasn't very hot when you started; but if you drive and then EOC at 35mph, it may be hot when you kill the engine.

Starter wear doesn't seem to be a problem who people who EOC and use the starter to restart, they claim normal life from their starters and batteries. However it seems like a better idea to bump start (obviously, for manual transmissions only) if you EOC on a regular basis (except then you worry about wear to the clutch and the synchro in whatever gear you use).

Maybe you could list it as a hybrid??? Sounds good anyway.

In my '97 Escort Wagon I often start a coast in gear and then if I see the hill is steep enough to maintain a decent speed shift to neutral both with engine on and often see the scan gauge jump as much as 100+ mpg when I shift to neutral. I have coasted down mountains in neutral with the engine running and experienced 350+ mpg according to the scan gauge.

There is an adjustment where you can adjust the amount of fuel you actually added to the car and If you will use it your scan gauge readings will be more precise. My last tank the scan gauge was off by 2 tenths of a mile per gallon, but I had to use this adjustment to get precise readings.

The scan gauge gets it information from the ECU, but there are also manual calibrations that can be made if necessary. The calibration is to be made when you fill the tank if you don't put in the same amount of fuel the ECU says it has used you can enter that information which makes the scan gauge recalibrate everything on the next tank and all tanks thereafter unless you make another change.

No DFCO :(

Thanks for the Scangauge tip. I need to set to Hybrid mode. My engine off coasts are currently not be analyzed. The Scangauge shuts off after 5 second or so. I have been using only engine on coasts in neutral or DFCO for this reason with the Yaris.

How long until someone is coasting around with their engine off and no power brakes and it ends in a tragedy.

That's partly why I don't shut the engine off. I'm coasting in a 6,000 lb vehicle. I need power brakes and steering.

-Jay

Same old FUD. EOC isn't right for everyone. My power brakes work fine for 3 or 4 heavy applications after I shut off the engine. Also, when I EOC, I'm always ready to bump-start and I do so any time I see any possibility that I might need to slow (since I don't want to restart with the key).

Anyway, my legs are plenty strong to stop the car reasonably after the power brakes run out of boost. I'm a 220 pound ex-bicyclist in a 3000 pound car, not a 130 pound twig in a 5000 pound SUV...

I mainly practice EOC on roads like this:
https://lh4.ggpht.com/ronanian/SDleut...8/IMG_0908.JPG

Don't know but it always gives a readout of actual MPG. Anyway it is nice to be coasting down hill in neutral and see you are getting 200-350 MPG.

I agree with this 100%. I'm also an ex bike racer who still rides at least 4 times per week, I have no problem locking up all 4 tires even after the brake booster has lost all vacuum. I've tried it under controlled conditions so I'd know what I'm capable of in an emergency. This isn't for everyone, only those who are willing and capable of giving 100% attention.

With all the latest distractions inside vehicles, (Nav systems, radio, CD, MP3, DVD, carPC, cell phone, etc.) it's a wonder we aren't smashing into each other more often.

It depends on how much you can leg press and most people can press a fair amount but not all brakes are vacuum assisted, my brakes us a simple hydraulic master cylinder which goes into a ABS pump, even with the engine off I have full braking power, I justdon't have ABS as its an electrical pump.

The only problem is I have power steering which is really heavy without the pump.

I just installed a fuel cut of switch as a theft prevention measure and so I can coast and kill the engine and start it with the flick of a switch, tuning my key will wear out my barrel or brake my key one day!:)

Why would electrical ABS not work? Do you not turn the key back to "On"? That is a very important part of EOC, so all your electrical stuff will work.

My power steering is electric, common on lots of cars in the past few years.

been driving ~35 miles EOC per tank. if i can get that up to 40, that's over 1k miles over the course of a year.

that is significant, especially if fuel prices continue to rise.