Ignition vs. Roll start?

[Alypuppy]

I must say I am impressed that with the Yaris mileage obtaining 40mpg over 1368 miles with a good mix of long freeway driving through New York and Massachusetts on winter fuel and tires. I cannot wait for summer!

However, I have a question. There are a lot of hills in my area and I often find places to cost for over a quarter of a mile. For these I turn of the car and let it roll and am even able to roll into and park my car in the school parking lot after .2 miles of costing and over 360 degrees of turning.

Most of my coasting, though, is when I see a red light in the distance. Sometimes the light turns green and I love the extra mpg boost from not having to start from a full stop, but I would like to know:

--> Which is better? Roll start the car in an appropriate gear? Or use the ignition system to start the car? Also, many say the wear and tear of ignition is similar to 7 seconds of the engine being on, so I turn my car off for nearly every light and am debating about turning off the car to roll up to stop signs... is there too much of a good thing? I do use the fuel shutoff DFCO (sp) as well, but I find I would rather just turn the car off and coast for greater distances.

Also, did I notice that the ODO only counts when the car is actually in the on position? After driving an SUV, the lack of power steering in the Yaris feels like the power steering in my Xterra, and it seems the break hydraulics only repressurize when the engine is on. I cannot afford a Scangauge, but do I have to turn the car back to the on position without igniting the engine to have a more accurate mileage calculation? Plus, it gets a little cranky and likes to turn the engine back on if it has not spun down fully and it is a bit distracting to have to turn the car on and off several times to finally but the engine to sleep.
Is this true for the other hypermilers? It's funny, sometimes I feel like my car is off more than it is on!


Thank you
Alypuppy

09 HB Manual Trans.

[BailOut]

Originally Posted by Alypuppy

I must say I am impressed that with the Yaris mileage obtaining 40mpg over 1368 miles with a good mix of long freeway driving through New York and Massachusetts on winter fuel and tires. I cannot wait for summer!

However, I have a question. There are a lot of hills in my area and I often find places to cost for over a quarter of a mile. For these I turn of the car and let it roll and am even able to roll into and park my car in the school parking lot after .2 miles of costing and over 360 degrees of turning.

Most of my coasting, though, is when I see a red light in the distance. Sometimes the light turns green and I love the extra mpg boost from not having to start from a full stop, but I would like to know:

--> Which is better? Roll start the car in an appropriate gear? Or use the ignition system to start the car? Also, many say the wear and tear of ignition is similar to 7 seconds of the engine being on, so I turn my car off for nearly every light and am debating about turning off the car to roll up to stop signs... is there too much of a good thing? I do use the fuel shutoff DFCO (sp) as well, but I find I would rather just turn the car off and coast for greater distances.

Also, did I notice that the ODO only counts when the car is actually in the on position? After driving an SUV, the lack of power steering in the Yaris feels like the power steering in my Xterra, and it seems the break hydraulics only repressurize when the engine is on. I cannot afford a Scangauge, but do I have to turn the car back to the on position without igniting the engine to have a more accurate mileage calculation? Plus, it gets a little cranky and likes to turn the engine back on if it has not spun down fully and it is a bit distracting to have to turn the car on and off several times to finally but the engine to sleep.
Is this true for the other hypermilers? It's funny, sometimes I feel like my car is off more than it is on!


Thank you
Alypuppy

09 HB Manual Trans.

Hello Alypuppy,

It sounds like you're off to a great start with hypermiling!

When you are moving at anything faster than 10 MPH and want to restart, bump start in 5th and then quickly shift to the appropriate gear and go. I do this several times per day.

Correct, the odometer only increments when the ignition switch is in the "On" position. This is also the necessary switch position for the electric power steering assist.

Yes, the difficulty with turning the engine off is normal in this car. I'm not sure why but I think it is due to the fuel that is queued up on the rail when we stop the engine at higher RPM. My trick is to cycle the ignition switch to the "Off" position, count to two-one-thousand, then cycle it back to the "On" position.

[Alypuppy]

Thank you Brian! =o)

[sbergman27]

Just drive normally. The Yaris is smart enough to cut the fuel completely when:

1. The accelerator pedal is at idle position.
2. The transmission is in gear.
3. The clutch is engaged.
4. Engine speed is above 1100 rpm. (I think it's 1100 anyway.)
5. Engine is at normal operating temperature.

Your fuel consumption will be zero under those conditions. Not even the normal 0.2 GPH for idling will be used. Search for "DFCO", or "Deceleration Fuel Cut Off".

-Steve

[1stToyota]

Originally Posted by Alypuppy

I must say I am impressed that with the Yaris mileage obtaining 40mpg over 1368 miles with a good mix of long freeway driving through New York and Massachusetts on winter fuel and tires. I cannot wait for summer!

However, I have a question. There are a lot of hills in my area and I often find places to cost for over a quarter of a mile. For these I turn of the car and let it roll and am even able to roll into and park my car in the school parking lot after .2 miles of costing and over 360 degrees of turning.

Most of my coasting, though, is when I see a red light in the distance. Sometimes the light turns green and I love the extra mpg boost from not having to start from a full stop, but I would like to know:

--> Which is better? Roll start the car in an appropriate gear? Or use the ignition system to start the car? Also, many say the wear and tear of ignition is similar to 7 seconds of the engine being on, so I turn my car off for nearly every light and am debating about turning off the car to roll up to stop signs... is there too much of a good thing? I do use the fuel shutoff DFCO (sp) as well, but I find I would rather just turn the car off and coast for greater distances.

Also, did I notice that the ODO only counts when the car is actually in the on position? After driving an SUV, the lack of power steering in the Yaris feels like the power steering in my Xterra, and it seems the break hydraulics only repressurize when the engine is on. I cannot afford a Scangauge, but do I have to turn the car back to the on position without igniting the engine to have a more accurate mileage calculation? Plus, it gets a little cranky and likes to turn the engine back on if it has not spun down fully and it is a bit distracting to have to turn the car on and off several times to finally but the engine to sleep.
Is this true for the other hypermilers? It's funny, sometimes I feel like my car is off more than it is on!


Thank you
Alypuppy

09 HB Manual Trans.

Originally Posted by sbergman27

Just drive normally. The Yaris is smart enough to cut the fuel completely when:

1. The accelerator pedal is at idle position.
2. The transmission is in gear.
3. The clutch is engaged.
4. Engine speed is above 1100 rpm. (I think it's 1100 anyway.)
5. Engine is at normal operating temperature.

Your fuel consumption will be zero under those conditions. Not even the normal 0.2 GPH for idling will be used. Search for "DFCO", or "Deceleration Fuel Cut Off".

-Steve

+1

Yes, just drive normally, and let the car do its job...no need for the added distraction

[BailOut]

Originally Posted by 1stToyota

+1

Yes, just drive normally, and let the car do its job...no need for the added distraction

I wholeheartedly disagree. The car only knows how to do its job one way, and that's the way the engineers thought it out. Their way is by far not the only way.

And cycling the ignition is not a "distraction". Your eyes don't leave the road, you still have assisted steering, and the brakes are good for 4-5 touches. Seriously, of all the things that one can gripe on for being a distraction while driving, cycling the ignition is at the bottom of my list.

There is a time and place for DFCO usage but it has two severe limitations:

1) It steals momentum.
2) The engine uses fuel again once any of its conditions are no longer met.

Coasting with the engine off is much more efficient in all aspects when you know you'll be coming to a stop for a while, or when you want to maintain more momentum in between the times you let the engine run.

[fmicle]

The only concern that I have about roll starting the car is based on an article that I read a few years back. There is a risk for unburnt fuel to end up in the catalytic converter, where, together with a spark from the engine (since the first cat is quite close to the exhaust header) could cause a burn (mini-explosion) inside the cat. That would most likely destroy it.

Having said that, I've roll-started the Yaris a few times before and everything was fine, but I don't think I'll ever try to roll-start it when the engine is cold.

Back home in Romania, when I was a kid, my dad had a crappy car and I remember the countless times we would push it down the street for half a block to start it. But that was an older car with a carburetor engine.

Since most people have automatic transmissions here in the US, I always wondered, is it possible to roll start an AT car? I remember my Jeep Cherokee had a low gear (1), the only setting that would give me engine brake, but I've never tried to roll start it... I was afraid of breaking it

[Yaris Hilton]

No, you can't roll start an automatic.

[1stToyota]

Originally Posted by Alypuppy

I must say I am impressed that with the Yaris mileage obtaining 40mpg over 1368 miles with a good mix of long freeway driving through New York and Massachusetts on winter fuel and tires. I cannot wait for summer!

However, I have a question. There are a lot of hills in my area and I often find places to cost for over a quarter of a mile. For these I turn of the car and let it roll and am even able to roll into and park my car in the school parking lot after .2 miles of costing and over 360 degrees of turning.

Most of my coasting, though, is when I see a red light in the distance. Sometimes the light turns green and I love the extra mpg boost from not having to start from a full stop, but I would like to know:

--> Which is better? Roll start the car in an appropriate gear? Or use the ignition system to start the car? Also, many say the wear and tear of ignition is similar to 7 seconds of the engine being on, so I turn my car off for nearly every light and am debating about turning off the car to roll up to stop signs... is there too much of a good thing? I do use the fuel shutoff DFCO (sp) as well, but I find I would rather just turn the car off and coast for greater distances.

Also, did I notice that the ODO only counts when the car is actually in the on position? After driving an SUV, the lack of power steering in the Yaris feels like the power steering in my Xterra, and it seems the break hydraulics only repressurize when the engine is on. I cannot afford a Scangauge, but do I have to turn the car back to the on position without igniting the engine to have a more accurate mileage calculation? Plus, it gets a little cranky and likes to turn the engine back on if it has not spun down fully and it is a bit distracting to have to turn the car on and off several times to finally but the engine to sleep.
Is this true for the other hypermilers? It's funny, sometimes I feel like my car is off more than it is on!


Thank you
Alypuppy

09 HB Manual Trans.

Originally Posted by BailOut

I wholeheartedly disagree. The car only knows how to do its job one way, and that's the way the engineers thought it out. Their way is by far not the only way.

And cycling the ignition is not a "distraction". Your eyes don't leave the road, you still have assisted steering, and the brakes are good for 4-5 touches. Seriously, of all the things that one can gripe on for being a distraction while driving, cycling the ignition is at the bottom of my list.

There is a time and place for DFCO usage but it has two severe limitations:

1) It steals momentum.
2) The engine uses fuel again once any of its conditions are no longer met.

Coasting with the engine off is much more efficient in all aspects when you know you'll be coming to a stop for a while, or when you want to maintain more momentum in between the times you let the engine run.

Maybe not to you, but it is for the OP. If you're quoting me, it's because I was quoting the OP. I wouldn't know, I'd never be silly enough to kill my engine while driving.

[sbergman27]

Originally Posted by 1stToyota

I wouldn't know, I'd never be silly enough to kill my engine while driving.

It seems that some hypermilers don't care that much about safety, steering, or braking except insofar as particular techniques involving them might yield a half a percent increase in their MPG figures:

http://tinyurl.com/yg2e4kz

And honestly, to someone who's other car regularly gets in the 50-60 mpg range when driven normally... it seems a little silly to me to see Yaris drivers going to such lengths to go from forty-something to forty-something-point-one.

-Steve

[Tamago]

save gas while slamming into the car in front of you when you have no power brakes?

yeah that sounds like a hypermiler.

[sbergman27]

Originally Posted by Tamago

save gas while slamming into the car in front of you when you have no power brakes? yeah that sounds like a hypermiler.

Momentum would be conserved.* So while the collision would hurt your fuel economy slightly, the guy you rear end should see a slightly better number on his next fill up.

-Steve

* Minus a little energy lost to heat during the collision itself.

[Tamago]

Originally Posted by sbergman27

Momentum would be conserved.* So while the collision would hurt your fuel economy slightly, the guy you rear end should see a slightly better number on his next fill up.

-Steve

* Minus a little energy lost to heat during the collision itself.

i am literally rolling on the floor laughing. thank you for your perfect explanation of "conservation of energy" law.

[Bluevitz-rs]

Originally Posted by Yaris Hilton

No, you can't roll start an automatic.

That's not entirely true. The old 2 speed powerglide transmissions have a transmission pump on the output shaft making it possible to build enough pressure inside to spin the engine. Though I think you'd need to get it going about 20-30km/h before that would happen.

But as for the regular Auto tranny, not a chance in anything. In fact, you most you can't even flat tow because the bearings inside the transmission don't have any pressurized lubrication due to the fact that the pump is located on the input shaft. So without the engine turning you have no oil circulation and could end up with fried bearings.

PS, that goes for you hypermilers out there with autos. Shut your engine off at your own risk of doing costly internal damage while trying to save a few pennies of fuel.

[BailOut]

Originally Posted by Tamago

save gas while slamming into the car in front of you when you have no power brakes?

yeah that sounds like a hypermiler.

You seemed to have missed the point that the brakes are still good for 4-5 touches before the vacuum needs to be recharged. I would also like to point out that in well over 3mil miles of hypermilers on the road, not a single hypermiling-related accident has been reported by drivers nor by any police force anywhere in the world.

I understand that hypermiling is different than what you know, but please do not sensationalize it. It is simply a different way to drive a car, and it works.

[sbergman27]

Originally Posted by BailOut

You seemed to have missed the point that the brakes are still good for 4-5 touches before the vacuum needs to be recharged.

And then there's steering... and added distraction... and delay in getting the engine going and the transmission back in gear should you unexpectedly need it. The list goes on...

I would also like to point out that in well over 3mil miles of hypermilers on the road, not a single hypermiling-related accident has been reported by drivers nor by any police force anywhere in the world.

You cannot possibly make that claim with any certainty. And it's very likely not true. I'd like to see some concrete evidence in support of that claim.

I understand that hypermiling is different than what you know, but please do not sensationalize it. It is simply a different way to drive a car, and it works.

Unsafe driving practices are unsafe driving practices. No matter how you want to want to gloss over them. Pointing out the added danger incurred by the hypermilers, and others who have to share the roads with them, is not, by any means, "sensationalizing" the matter.

There are reasonable fuel saving practices... which are, in general, good for safety, as well. And then there are foolish practices which annoy and endanger the hypermiler and others. Fortunately, the reasonable, safe, and non-annoying ones also yield the bulk of the actual FE benefits.

-Steve

[Tamago]

Originally Posted by BailOut

You seemed to have missed the point that the brakes are still good for 4-5 touches before the vacuum needs to be recharged.

4-5 touches, but in that panic moment when you NEED the vacuum, where is it? .8 miles back when you getting a boner over saving 3oz of fuel.....

I would also like to point out that in well over 3mil miles of hypermilers on the road, not a single hypermiling-related accident has been reported by drivers nor by any police force anywhere in the world.

so you think a hypermiler is going to report that his/her own stupid actions caused him to rear-end the guy in front of him? "yes officer, well, i turned off my engine, to save fuel, and somehow it rear-ended the guy in front of me in the process".. yeah right... he/she told the cop that the "throttle stuck" and he was forced to slam into the guy in front..... wait, that sounds VERY familiar.

I understand that hypermiling is different than what you know,

i perfectly understand the obsession with "saving 3mpg".. it's much like collecting baseball cards or "action figures" hoping that in 30 years they'll be worth something..

but please do not sensationalize it.

there's nothing sensational about wasting time to save pennies It is simply a compromise for time over distance.. a different way to drive a car, and it works.[/QUOTE]

you do what you gotta do... but congratulating a guy about his ability to coast down a hill sans-power-braking is just retarded. it's not worth the ounces of fuel saved... especially considering the fact that most of you are wasting the money spent on gas...... on some other stupid obsession, like action figure collections...

[sbergman27]

Originally Posted by Tamago

it's not worth the ounces of fuel saved...

One thing that generally gets lost in these discussions is the true motivation. It's not the pennies worth of fuel saved. It's being able to go on forums like these and say "I finally hit 50 mpg!" and have a couple dozen people 'attaboy you for doing so well. That's the true motivation and potential pay off.

-Steve