et00

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?

Rambotk3

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.

D4u2s0t

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.

ItalianJoe1

iTrader: (10)

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.

D4u2s0t

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.

et00

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.

D4u2s0t

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.

ItalianJoe1

iTrader: (10)

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

Herndon_High_SS

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.

D4u2s0t

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

krispy

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

alleycat58

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.

krispy

after 2.8k miles my DIC was within 0.5% accurate

https://www.cobaltss.net/forums/fuel-economy-hypermiling-165/you-can-believe-dic-124725/

it calculates it off of injection quantity, its accurate

Witt

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.

jerrodmann

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....

light'bolt

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....

krispy

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

OniMirage

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.

Witt

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.

krispy

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.

Blue_Balt

iTrader: (1)

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.

maverick0716

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.

lewisb13

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

an0malous

yeah, dfco sucks ass.
i mean, wtf would i know about it anyway.

D4u2s0t

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.