Shifting into neutral at signals

[quickshade]

I can't say much on the automatic trans and shifting it from N to D at lights. In my area we have 2-3 lights that are long lights and I do put it in N at those lights, just because my engine seems to run smoother and idle better. As for wasting more gas by turning the engine off and then on, NOT TRUE, recent studies show you burn more fuel by letting your car run while waiting somewhere than to just turn it off and restart it. It was something like 1/2 MPG for every 2 minutes you sit somewhere.

[kasey07]

1.85??? in cincinnati its 1.65

[vsupra123]

In hawaii gas is still about $2.90 out of costco....Costco gets something like $2.30....You can imagine the lines....

Thanks for backing me up quickshade! I got that info from a show that featured "hyper milers" or something near that name. They are super hardcore with conserving fuel. They get something like 100mpg in a prius and about 50mpg in a v6. It involves a lot of turning off the car while coasting and at lights, etc. It's flippin amazing.

[GMANtt]

^ any link to that. sorry i doubted your philsophy lol. I thought you would burn more feel by turning it on and off all the time.

[saywat?]

Originally Posted by UzumakiNaruto

what light you at for more than 5 mins??? i know last night when i got out of my house i had to wait at my light for like 5-6 mins because a firetruck passed by and that made my light stay red..then when it was spouse to turn it still stayed red THEN another firetruck/ambulance came by and that just made my night....but i do hope where ever they was going they saved a life

ditto 5 minutes lights in hawaii are not common at all...i dont kno of one...id be more concerned with the wear on the starter

[vsupra123]

5 mins was kind of an over exaggeration....Maybe 3 or 4 mins. There are a few lights in waimalu that are god forsaken....

[LSUtigerME]

you can save some wear on the torque converted by shifting to neutral. This disengages the "clutch" and puts less load on the motor. You basically save the amount of fuel it would take to circulate that fluid, fuel savings isn't much. As for turning it off, you will save fuel and it's common practice for hypermilers. But, you will stress your battery and started.

As for fuel delivery, the altima cuts fuel when the accelerator is lifted and your moving, I believe it's only when above 1000 or so rpm. It has to have fuel to idle. Every 2.5 should be aware of this if they've ever heard of the precat problems (think about how flowing exhaust would get pulled back into the engine).

[davedaman]

I'm fairly certain that some of these hypermilers' practices are illegal. Shutting your engine off coasting to a red light/stop light I can almost guarantee is illegal for safety reasons. These people also remove side view mirrors, shave door handles, anything to eliminate a miniscule amount of drag. I would rather burn that little bit of gas than put the wear and tear on my starting system, though, but to each their own.

[1trucavalier]

imagine the wear on the starter and batt cutting that car on and off

[quickshade]

I'm not saying that at every light you should shut your engine off, but in some cases when your with friends or picking someone up and waiting in the driveway for them it doesn't hurt to turn off the car for the 5 minutes your going to be there. As for every light you come to I would never do that.

[Agent00Alti]

i dunno whenever i put mine into neutral the RPM's seem higher than when its in D. (thus meaning more fuel consumption?) and when in neutral the tranny is disengaged from the engine which is why it seems to idle smoother. and gas is cheap now...(never thought id say that about 2.25 for premium)

[LSUtigerME]

^ Higher RPM does not necessarily mean more fuel consumption. The RPM changes because the engine has a higher load.

[kmikl-GAM]

Originally Posted by steveracinRR

you probably burn more gas starting the car back up than you would of just idling.. Plus the extra wear and tear on the starter, battery, and overall engine.

Nope, the amount of fuel you save turning the engine off is a lot more than if you idle for more than 30 seconds. I wouldn't do this in traffic though. Wear on the engine is negligable, if you're not sitting for over 4 hours, your oil is still warm and up in the cylinders, the starter is pretty robust, and the battery only really wears out if you drain it to dead often enough that the plates get caked with sulfides. Fuel is also not really a concern as your engine and catalytic converter are warm and lighting off.

Slipping it into neutral on an AT car seems a little silly if you ask me, there's really no savings doing this on any part of the transmission or the engine. If the vibration is THAT bad, I'd wager it's something you'd want to get checked out, and pronto... IDK for sure though, I haven't driven a AT Altima yet.

Originally Posted by steveracinRR

Car is like a computer...its better to leave it running for long periods of time, rather than turning it on a and off a bunch of times.

WAY WRONG. I've worked as a tech support rep for a couple of companies: This might have been true 10-15 years ago, it's not true now. Power supplies are far more robust and can condition start-up power a lot better than even 5 years ago. Even then, if you leave a computer on all the time, you're opening up the possibility of a power spike or brown-out to kill your PS's voltage regulators and then the rest of the computer. Basically the same rule applies here: if you don't need it to be on, LEAVE IT OFF!!!

Originally Posted by steveracinRR

And im willing to bet its against the law too, if you knowingly turn your car off and block the way of a emergency vehicle cause your car wont start back up....i can see it being a problem. Are you really that broke with gas prices at 1.85 you need to do this??? you need to stop it right away.

You'd have to check your state/provincial laws. I wouldn't do this at a light or stop sign, but if I'm going to be waiting for someone at a mall or something I'll turn the car off.

[samo]

Originally Posted by carfreak67

You need to understand how an automatic transmission works to find the answer to your question.
But all in all, while you may save a tiny amount of wear on your torque converter you will be causing even more wear on the bands and clutches in the transmission.

My brother who is a mechanic told me the same thing. I wouldn't do it unless you're trying to wear out your tranny sooner than later.