So I was reading that it is techincally better on mpg to coast in gear than to pop it in neutral cause of DFCO...

I decided to try for myself and sure enough they are comparable except!!!

And this is my own opinion on this but it I feel the car slows down considerably more from gear/mechinical resistance. After all the car is basically turning the engine all by itself with the fuel cut off. I find myself giving it gas more often to compensate. Especially now that it is already in gear.

I just got the car 2 weeks ago after years of neutral coasting with my 96' S10. And I'm trying to be as open minded as I can. Still I am not quite convinced that its a huge step up from neutral coasting...

Thoughts?

Ya i agree with you, i do feel the car slow down a lot but i think it does make a huge difference. I noticed a 2 to 3 mpg difference per gallon which isn't bad! So if you are not in a hurry then i think that is is worth it.

they are not comparable. if you're going into neutral, you're driving incorectly. too many topics on this to get into it all, it's been discussed a million times. when you are in neutral, you are using gas. when you're coasting in gear, you are not. it's quite simple. no gas > gas. shifting into gear from neutral is also harder on your clutch, tranny, and synchros than leaving it in gear.

they are not comparable. if you're going into neutral, you're driving incorectly. too many topics on this to get into it all, it's been discussed a million times. when you are in neutral, you are using gas. when you're coasting in gear, you are not. it's quite simple. no gas > gas. shifting into gear from neutral is also harder on your clutch, tranny, and synchros than leaving it in gear.

Not to mention that it delays response time in an emergency, if someone is to swerve out at you and you need to get on the gas, you have to waste at least half a second putting the car back in gear before you can accellerate.

Not to mention that it delays response time in an emergency, if someone is to swerve out at you and you need to get on the gas, you have to waste at least half a second putting the car back in gear before you can accellerate.

yep... there's a ton of reasons why it's no good. if the op reads through some of my previous posts, i have done some good posts about it, along with other members. i get pm's everyday about the topic. too many closed-minded people that tell you you're wrong to post it all again.

Not to mention that it delays response time in an emergency, if someone is to swerve out at you and you need to get on the gas, you have to waste at least half a second putting the car back in gear before you can accellerate.

Good point. No need to be dumping the clutch either.

yep... there's a ton of reasons why it's no good. if the op reads through some of my previous posts, i have done some good posts about it, along with other members. i get pm's everyday about the topic. too many closed-minded people that tell you you're wrong to post it all again.

Maybe this is a sore subject... Srry I didn't see your prev ones. Maybe you could link? You are in Northern NJ? Drop by Newton and show me how its done then.

Good point. No need to be dumping the clutch either.



Maybe this is a sore subject... Srry I didn't see your prev ones. Maybe you could link? You are in Northern NJ? Drop by Newton and show me how its done then.

it's not that it's sore, i have no problem helping people that want to learn. it's just that so many people on this site think they know it all, and when you try to explain things they just tell you that you're wrong and stupid.

but as far as someone that's serious about learning, i have no problem answering any questions, or even helping install parts, or anything i can do to help. i've helped a shitload of north jersey guys get parts on their cars, and never ask for a dime. i've shown some how to drive their car, and always get tons of pm's asking for advice. i LOVE helping people that are willing to learn. but i don't have a lot of patience for people that are too thickheaded and stubborn to admit when they're wrong. we all have something to learn, and the only way to learn is to have an open mind. i don't claim to know everything, because i certainly don't. but, when i do know an answer to a question, or have good advice to give, i'll most certainly take the time needed to help the best i can.

that being said, if you have any questions feel free to shoot me a message. it's easier that way, it avoids all the bullshit.

Besides, my car sounds sexy when coasting in gear. I am catless with DFCO turned off though :)

it's not that it's sore, i have no problem helping people that want to learn. it's just that so many people on this site think they know it all, and when you try to explain things they just tell you that you're wrong and stupid.

but as far as someone that's serious about learning, i have no problem answering any questions, or even helping install parts, or anything i can do to help. i've helped a shitload of north jersey guys get parts on their cars, and never ask for a dime. i've shown some how to drive their car, and always get tons of pm's asking for advice. i LOVE helping people that are willing to learn. but i don't have a lot of patience for people that are too thickheaded and stubborn to admit when they're wrong. we all have something to learn, and the only way to learn is to have an open mind.

that being said, if you have any questions feel free to shoot me a message. it's easier that way, it avoids all the bullshit.

Well put. Until a post you made about a month ago I've been throwing it in neutral since I got my license. Thank god I've only been driving 3 years. Thanks D4u2s0t.:)

Well put. Until a post you made about a month ago I've been throwing it in neutral since I got my license. Thank god I've only been driving 3 years. Thanks D4u2s0t.:)

you're welcome, and glad to hear i helped! :twothumbs:

on the instant mpg what I've noticed:

when coming up to a stop in neutral almost always 99 mpg
when coming up to a stop in gear is almost always less than 99 mpg

not that any of that really matters on a stop, you arn't using much fuel regardless, but with it in gear you get more engine braking

on the instant mpg what I've noticed:

when coming up to a stop in neutral almost always 99 mpg
when coming up to a stop in gear is almost always less than 99 mpg

not that any of that really matters on a stop, you arn't using much fuel regardless, but with it in gear you get more engine braking

That's in no way shape or form indicative of real world MPG. I'm not sure what the calculation is that is used to calculate, but I'm guessing it has something to do with engine RPM. I never neutral coast and my MPG is always higher when I do the calculations after a fill up than my DIC claims it to be.

That's in no way shape or form indicative of real world MPG. I'm not sure what the calculation is that is used to calculate, but I'm guessing it has something to do with engine RPM. I never neutral coast and my MPG is always higher when I do the calculations after a fill up than my DIC claims it to be.

after 2.8k miles my DIC was within 0.5% accurate

http://www.cobaltss.net/forums/showthread.php?t=124725

it calculates it off of injection quantity, its accurate

after 2.8k miles my DIC was within 0.5% accurate

http://www.cobaltss.net/forums/showthread.php?t=124725

it calculates it off of injection quantity, its accurate

It calculates it off your incoming airflow as measured by the MAF sensor. While in gear airflow will be higher obviously.

A better way to show it is to actually monitor injector pulse width as scanned by a tech 2 or HPtuners.

I can see and understand to stay in gear if you are not coasting to a stop. The only time I slip the car into neutral is when I know the car is coming to a stop in 1/2 mile or so. So with that being said, it that ok? I can't see how it could hurt any mechanical parts.

I never pull my car out of gear coast for a little bit, and then slip it back into a lower gear....

I used my AFR gauge as a quick test to this and when I coast in gear its shoots up to over 20 AFR. Throw it to neutral and a quick 20 AFR then it resumes back to 14.7 almost immediatly. But once you start to slow down in gear it will gradually get back to 14.7....

It calculates it off your incoming airflow as measured by the MAF sensor. While in gear airflow will be higher obviously.

A better way to show it is to actually monitor injector pulse width as scanned by a tech 2 or HPtuners.

I thought it calcuated it off of injection quantity (which would be directly correlated to injecter pulsewidth)

ick another thread. I still think the numbers are far to close to pronounce one method over the other as king though being in gear has more benefits than neutral.

I thought it calcuated it off of injection quantity (which would be directly correlated to injecter pulsewidth)

An injector pulsewidth is nothing more than a measurement of time to the PCM. If you swap injectors you burn more fuel at the same pulsewidth. The injector flow rate table corrects the injector size so the correct amount of time the injector is open is accurate thus reducing pulsewidth to deliver the same amount of fuel in a comparable situation.

An injector pulsewidth is nothing more than a measurement of time to the PCM. If you swap injectors you burn more fuel at the same pulsewidth. The injector flow rate table corrects the injector size so the correct amount of time the injector is open is accurate thus reducing pulsewidth to deliver the same amount of fuel in a comparable situation.

They does nothing to explain the DIC calculation, only how switching injection could throw it off it was calculated using injector pulse width. I was questioning how you figure its based off of the MAF since A/F ratio is not constant.

you're welcome, and glad to hear i helped! :twothumbs:

You've helped me a lot also.

Ever since I've been rev match downshifting, I do notice an increase in MPG and that I'm also driving the car right now.

According to my Dashhawk, with gas mileage in mind it's better to leave your car in gear as it puts less load on the injectors.

Of course theres a trade off. SLIGHTLY decreased fuel consumption versus wear n tare on your tranny and clutch.

yeah, dfco sucks ass.
i mean, wtf would i know about it anyway.
http://img.photobucket.com/albums/v34/dragongirl78/mpg-1.jpg

Of course theres a trade off. SLIGHTLY decreased fuel consumption versus wear n tare on your tranny and clutch.

it's not all about fuel consumption.

can you explain how the wear and tear compares to normal driving? besides just saying "well it's in gear so it's more than if it's in neutral". just curious if there's any real basis to this, or if you're just guessing. if there IS a real basis, how much wear is there over putting it in neutral? how much does it shorten tranny life?.

the main factor is safety. we've been saying that forever. and, if you put it in neutral, and then have to go back into gear, you're stressing the tranny syncrhos and clutch more.

I'm sorry if I'm ignorant or lazy, but is this only on SC or TC models or does it include 2.2 and 2.4's? Also, does it only apply to manual or auto as well?

For a long time, I was one of those stick it neutral people...still am, but if it's better not to, I will change...then again, all my old cars didn't have the technology these new cars have.

Besides, my car sounds sexy when coasting in gear. I am catless with DFCO turned off though :)

Sound files?

Sound files?

Not really, you can hear it on some of my videos, but nothing dedicated to strictly getting exhaust sounds.

The car isn't healthy right now, so it sounds a little funny, very STIish, so no vids right now. :(

I'm sorry if I'm ignorant or lazy, but is this only on SC or TC models or does it include 2.2 and 2.4's? Also, does it only apply to manual or auto as well?

For a long time, I was one of those stick it neutral people...still am, but if it's better not to, I will change...then again, all my old cars didn't have the technology these new cars have.

off the top of my head, DFCO has been in nearly all cars since the late 80s early 90s

While dfco is great, the fuel savings are defeated if you blip the throttle for rev matching on downshifts. It's all in driving style.

While dfco is great, the fuel savings are defeated if you blip the throttle for rev matching on downshifts. It's all in driving style.

seriously, where do you guys get your info from?

When decelerating, I always keep it in gear, until like 15 mph. I either downshift, or just let it sit in 5th gear and than push in the clutch at 15mph. I like downshifting because it sounds badass & it's fun!

seriously, where do you guys get your info from?

Are you saying that is an inaccurate statement? I'm fairly certain i have delt with this more than you... so please lay off.

Depending on your driving style, if you downshift while decelerating and blip the throttle to rev match you will be using fuel.

There are a few senarios

1. when decelerating you pull out of gear and let the engine idle during your coasting

2. you decelerate and leave it in your cruising gear. You will be using DFCO for a while untill your rpms drop low enough to kick the injectors back on

3. You decelerate and keep it in the correct gear up preparing for a nice exit to a corner or preparing for the light to change as you roll up. In this case you will be doing the heel toe method and bliping the throttle to rev match. During this rev match, you will be using fuel to overcome the friction and pumping losses of the engine. Once the next lower gear is selected you will enter DFCO.

a blip in the throttle is a 0 load shot of gas for 1 second,
how can you possibly think that that will use more fuel than idling the engine all the way to a stop?

it may be just me, but it seems as though i barely slow down while trying to brake with my engine.... whereas with the lotus, its a much faster decelleration...

a blip in the throttle is a 0 load shot of gas for 1 second,
how can you possibly think that that will use more fuel than idling the engine all the way to a stop?

I never said that specifically.. i just said bliping the throttle takes away the full benefit of DFCO

You can have it either way, it totally depends on the rate of decel, the RPM you are matching, etc..

You guys realize im agreeing with you but trying to make you realize all the scenarios.. we can argue about a 0.1g decel or a 1.0g decel and come up with two different answers for maximized fuel economy during braking.

Does anyone have the FMEP data from the LSJ engne? it takes alot of energy just to spin a motor at "0" brake load to high rpms..

So DRIVING STYLE is the critical factor and DFCO is a benefical tool.

i would rather downshift without revmatching then neutral coast

i would rather downshift without revmatching then neutral coast

yes you would get great fuel economy... and afterall it is your clutch..

This doesn't apply for the supercharged models?

Thanks and sorry if it's adumb question. I'm no expert in this.

This doesn't apply for the supercharged models?

Thanks and sorry if it's adumb question. I'm no expert in this.

yes it does. :twothumbs

it applies to all cobalts I believe,

yes it does. :twothumbs

Cool, thanks! I'll give it a try!

it applies to all cobalts I believe,

It applies to almost every car made in the last 15 years.

Not only do you waste gas but it's illegal to neutral coast in some places. I fail to see how any benefits of coasting could outweigh those two very big negatives. :lol:

yes you would get great fuel economy... and afterall it is your clutch..

BZZZZZZZT. Wrong.

How are there so many stubborn dumbasses on this forum?

What wears your clutch more, full engagement while slowing down or sudden slipping when putting into a lower gear after coasting? Hmm?

Think before you type people.

Frankly, you want to get into a car accident, go ahead, neutral coast. One less moron in the world if you die in a mangled wreck because you couldn't get out of the way. I'm done trying to prove morons that staying in gear is safer for you, better for your car and just plain better overall.

NO MORE.

Drive safely or get off the road. When you coast in neutral you endanger yourself, your passengers and more importantly; me. DON'T FUCKING DO IT.

Transmission or MPG

BZZZZZZZT. Wrong.

How are there so many stubborn dumbasses on this forum?

What wears your clutch more, full engagement while slowing down or sudden slipping when putting into a lower gear after coasting? Hmm?

Think before you type people.

Frankly, you want to get into a car accident, go ahead, neutral coast. One less moron in the world if you die in a mangled wreck because you couldn't get out of the way. I'm done trying to prove morons that staying in gear is safer for you, better for your car and just plain better overall.

NO MORE.

Drive safely or get off the road. When you coast in neutral you endanger yourself, your passengers and more importantly; me. DON'T FUCKING DO IT.




thanks for the dumbass comment. If you only knew... lol

We were discussing pro's and cons of downshifting vs neutral coasing and its effect on fuel economy. Please take this argument in context and leave out the name calling.. because i am fairly certain calling people dumbasses does not increase saftey or MPG...

You dont seem to have the mental capacity to comprehend the arguments that i have posted 'for and against' this.. I am not biased either way and just wanted to get people 'thinking'... i guess im in the wrong forum for that..

my whole point, in relation to fuel economy there are different situations where neutral coasting gets better FE and vice versa

"It is the mark of an educated mind to be able to entertain a thought without accepting it." - Aristotle

Thanks

Transmission or MPG

If you rev match properly your clutch and transmission will be fine, and you will see better gas mileage.

my whole point, in relation to fuel economy there are different situations where neutral coasting gets better FE and vice versa

"It is the mark of an educated mind to be able to entertain a thought without accepting it." - Aristotle

Thanks

My whole point is it doesn't matter what fuel efficiency you get, neutral coasting is always unsafe. Don't do it. I don't care if it makes you get 500 mpg and gold dubloons shoot out of your air vents. Don't drive like an idiot.

There is zero merit to even consider driving unsafe for any mpg gain.

Zero...

None...

Nada...

Zilch...

End of story.

"You can never underestimate the stupidity of the general public."
--Scott Adams

My whole point is it doesn't matter what fuel efficiency you get, neutral coasting is always unsafe. Don't do it. I don't care if it makes you get 500 mpg and gold dubloons shoot out of your air vents. Don't drive like an idiot.

There is zero merit to even consider driving unsafe for any mpg gain.

Zero...

None...

Nada...

Zilch...

End of story.

"You can never underestimate the stupidity of the general public."
--Scott Adams

Have you ever talked on your phone while driving? My guess is yes you have.

that is SIGNIFICANTLY more "unsafe" than neutral coasting. So please get off your horse.

how about changing the radio station? Eating food? Talking to passengers? Looked at a billboard on the side of the road? Driven with only one hand on the wheel? (gasp!) Accelerated at more than 0.1g?, cornered at more than 0.1g? Ever have a thought go through your head that wasnt related to driving?.. etc..

I can argue that 90% of what you do while driving is unsafe and idiotic as well.. (besides, I never said how i drive.. i merely wanted to prove my point)

Why exactly did you purchase a Cobalt if you are so worried about saftey..? It gets better MPG than an SUV or a Volvo... yet is SIGNIFICANTLY less safe than an Volvo by all measured standards. So by your argument, EVERYONE should buy a volvo or SUV. Thats quite interesting... would your reason be because your cobalt "TURBOCHARGED" is fast and fun to drive or was it for Saftey????? Last time i checked "Spirited" driving was considered very unsafe as well!!

(Im sure your "performance meter" is to ensure saftey while driving....)

"Let He Who Is Without Sin Cast The First Stone"

You should never enter a battle of wits unarmed...

You should never enter a battle of wits unarmed...

Nor should you tell someone how they should coast, whether in gear or out of it. Its there own choice and it doesn't harm you unless your the dumb ass running the red light. Throwing names around Kazinova, is uncalled for and immature. This is a mature duscussion, lets try to keep it that way.

Nor should you tell someone how they should coast, whether in gear or out of it. Its there own choice and it doesn't harm you unless your the dumb ass running the red light. Throwing names around Kazinova, is uncalled for and immature. This is a mature duscussion, lets try to keep it that way.

I refuse to believe any conversation that involves one person promoting unsafe driving habits can be called "mature". "Dumb" would be far more applicable.

And you should tell someone how to coast, it's part of learning to drive, just like telling someone to ease into a stop instead of slamming on the brakes everytime. Sure you can do that, but you're likely to get rear-ended and the law will come down on you if you do.

Coasting is the exact same way, in gear or illegal, take your pick. There should be no discussion, at some point someone died because someone didn't know how to properly drive a standard transmission. Just saying.

Also, I can't remember the last time I actively advocated that people should talk on a cell phone while they drive to save time like people here have advocated an even more dangerous activity in the sake of "MPG".

I'm done trying to cram logic into your thick skulls.

Neutral Coasting is dangerous, don't do it, don't contemplate the fuel savings, don't talk about it. If someone said your could get 52mpg driving in reverse everywhere would you advocate that too.

"Stupid is as stupid does."
-Forrest Gump

I'm posting stupid quotes to point out how assinine it is to compare a message board argument to a philosophical debate...

"Stupid is as stupid does."
-Forrest Gump


"takes one to know one" - pee wee herman

no point in arguing with a wall i guess..

Especially when the wall is right. I turned the RPD to track engine power output. In suburbs with relatively spaced out stops I neutral coasted to a light and observed that the torque readout, like when I'm in neutral at a complete stop, it flickered between 1, 2 and 3 ft-lbs. Doing the same exact stop at 3k in 2nd gear made the power drop to zero, the air/fuel ratio meter blank and let me not use my brakes nearly as much.

Unless you are neutral coast for a mile or more down a hill you won't see a noticeable gain in mpg as compared to DFCO in gear. Combined with the fact that coasting that long in neutral would only occur in banking twisty roads or a steep downhill road, either of which is totally unsafe.

Done and done. Forever. Next topic.

Especially when the wall is right. I turned the RPD to track engine power output. In suburbs with relatively spaced out stops I neutral coasted to a light and observed that the torque readout, like when I'm in neutral at a complete stop, it flickered between 1, 2 and 3 ft-lbs. Doing the same exact stop at 3k in 2nd gear made the power drop to zero, the air/fuel ratio meter blank and let me not use my brakes nearly as much.

Unless you are neutral coast for a mile or more down a hill you won't see a noticeable gain in mpg as compared to DFCO in gear. Combined with the fact that coasting that long in neutral would only occur in banking twisty roads or a steep downhill road, either of which is totally unsafe.

Done and done. Forever. Next topic.

ah if only that one condition that you tested were always correct... You are one of those people who doesnt have enough intellect to comprehend the statements i made above..

most people dont drive at 3krpms at a constant speed.. you should upshift. which leads to my points made above. You have to downshift during the deceleration event to keep the engine operating in the DFCO mode.

Now you have 2 options, blip the throttle (using fuel) to downshift or jam the gear and let the clutch take all the slip

If you slow down holding 5th gear you will drag it below the point at which DFCO is operational and hold it even longer and the car will start to add fuel to keep the rpms up!

so, thanks for the test, but i could have already told you the outcome to it... Do it again at 1k - 1.5krpm in 5th and let me know how it goes..


If your driving aroud at 3krpm in 2nd, you dont care about fuel economy anyhow..

(remember, i have not stated which method i use, i am trying to show you that every situation is different)

If its done properly, and in the right situations, DFCO > neutral coasting in every single possible way.

the ONLY argument neutral coasting has in its favor, is you can increase your mileage if your to stupid to know how to drive properly.

end of story.

ah if only that one condition that you tested were always correct... You are one of those people who doesnt have enough intellect to comprehend the statements i made above..

I'm going to let the irony of that horrible sentence sink in for a little bit.

Whatever chief, I'll take my miniscule intellect elsewhere I guess. I'm too weak for you, you mental juggernaut.

Edit: I'm done trying to lay some truth on your asses. I can tell from your constant backpedalling that you know you're wrong.

an0molous: I'm beginning to see why you gave up on these chumps.

I'm going to let the irony of that horrible sentence sink in for a little bit.

Whatever chief, I'll take my miniscule intellect elsewhere I guess. I'm too weak for you, you mental juggernaut.

Edit: I'm done trying to lay some truth on your asses. I can tell from your constant backpedalling that you know you're wrong.

an0molous: I'm beginning to see why you gave up on these chumps.

Look.. i was not the one who came in here calling people dumbasses, idiots, chumps, etc... I dont know what your problem is but being a 'tough guy' on the internet seems to be working for you.. I dont want to deal with it.

anyways, this is not worth my time.. the internet doesnt matter and is no place for a debate that goes beyond surface discussion..

If you ever want to have a real discussion.. let me know. You might learn something...