Does putting automatic car in neutral for long idling periods relieve any engine/transmission stress?

[atikovi]

When I get caught by a train I put it in P but that's so I don't have to keep my foot on the brake plus this puts less wear on my brake lights

If you get caught by a train, you just hope you survive. Everything else is secondary.

 

[OppositeLocK]

If you get caught by a train, you just hope you survive. Everything else is secondary.

So what you're saying is best to leave it in drive so you can move out of the way quicker?

 

[OppositeLocK]

Here's an interesting question, on cars with "Brake Hold" systems, does pressing the button shift the transmission into neutral?

 

[atikovi]

So what you're saying is best to leave it in drive so you can move out of the way quicker?

How about just not stopping on railroad tracks?

 

[RateNate]

Interesting, that would not happen to be around Sacramento area would it? And that shop class would happen to have a rare Transmission Dyno as well?

It was sierra college actually, his name was Dan or something if I remember correctly. We are in rocklin north of sac. I know that he worked with pro dragster teams and helped them shave 0.50 sec by changing their tranny fluid from gear oil (transmission builder recommended) to what he put was atf, and it zoomed after that.

 

[RateNate]

Also Charles I would definitely put it in park/neutral if you end up having long idling time if it's over 5 minutes. Less stress worrying about hitting the person in front.

 

[Cujet]

I'm lazy, so I put the F150's into park when sitting for long lights. I don't like pressing the brake that long.

 

[gathermewool]

Also Charles I would definitely put it in park/neutral if you end up having long idling time if it's over 5 minutes. Less stress worrying about hitting the person in front.

I would turn the car off for long stops, weather and safety of the situation permitting.

 

[OppositeLocK]

I'm lazy, so I put the F150's into park when sitting for long lights. I don't like pressing the brake that long.

The new ones don't have auto brake hold?

 

[xgmad]

It depends on your transmission, certain solenoids are still engaged in park and neutral.


When disengaged the torque convertor does not need to start the impelling process due to there being no load. it moves as one i believe correct me if i am wrong

 

[vavavroom]

Squad cars typically idle a few hours every shift.

 

[OppositeLocK]

Squad cars typically idle a few hours every shift.

But they've usually got upgraded components?

 

[ripcord]

So you save fuel by idling to a stop than letting the ECU shut off the injectors and run the engine on a vacuum, which uses no fuel and also saves brakes due to engine braking.

Pretty smart.

I don't think this completely accurate. Injector output will never be zero for any length of time. If is the engine is running, the ECU MUST inject enough fuel to maintain close a stoichiometric fuel air mixture, otherwise the NOx levels go sky high and Mr EPA gets mad. Also, the cats require continual hot exhaust or they will cool down pretty quickly, which is another reason why injector output can't be at zero under prolonged deceleration.

 

[vavavroom]

But they've usually got upgraded components?

I don't know if they have upgraded transmissions.

 

[gathermewool]

I don't think this completely accurate. Injector output will never be zero for any length of time. If is the engine is running, the ECU MUST inject enough fuel to maintain close a stoichiometric fuel air mixture, otherwise the NOx levels go sky high and Mr EPA gets mad. Also, the cats require continual hot exhaust or they will cool down pretty quickly, which is another reason why injector output can't be at zero under prolonged deceleration.

Zero fuel = zero Nox. The cat will still be lit off after 30 seconds of engine-braking.

I never thought the injectors going to 0% injector duty cycle thing was in question.

Data logs from my previous STI show 0% IDC. My current and other vehicles I’ve driven go to max MPG (eg, 999 MPG) on the downhill.

 

[Shel_B]

Driving an auto like a manual makes no sense.

And yet there are automatics that are designed to be shifted. Toyota has for many years offered an auto trans with what they call "sequential shift" which not only allows up and downshifting, but encourages it. Porsche has used something similar called, I believe, Tiptronic. If you've never had the experience of being able to better control your auto trans, you might want to give such a system a try.

For those who have used such a system, it makes perfect sense.

 

[OppositeLocK]

I don't think this completely accurate. Injector output will never be zero for any length of time. If is the engine is running, the ECU MUST inject enough fuel to maintain close a stoichiometric fuel air mixture, otherwise the NOx levels go sky high and Mr EPA gets mad. Also, the cats require continual hot exhaust or they will cool down pretty quickly, which is another reason why injector output can't be at zero under prolonged deceleration.

Everything you've said is nothing other than speculation on your part. The driveline is what is turning over the engine, not fuel/air mixtures.

I don't know how many times this myth has to be propagated in auto circles but it's simply not true.

If you don't believe me find an open road, get up to a good speed and just let off the gas completely and observe the car as it slows down all the way. Once it slows down to a speed it would move at by itself if it were idling in drive (foot off brake in drive), you'll actually see, hear, and feel the injectors come on as the duty cycle change. If you're still in doubt, hook up an oscilloscope.

 

[OppositeLocK]

And yet there are automatics that are designed to be shifted. Toyota has for many years offered an auto trans with what they call "sequential shift" which not only allows up and downshifting, but encourages it. Porsche has used something similar called, I believe, Tiptronic. If you've never had the experience of being able to better control your auto trans, you might want to give such a system a try.

For those who have used such a system, it makes perfect sense.

I think almost every automatic has this now but I've never seen nor heard these systems be liked nor appreciated very much. It's usually been my experience that it's mainly a gimmick and you get better results with putting the tranny in the appropriate mode (sport, tow/haul, etc).

Personally speaking, I've never found using them a pleasurable experience. What's worse, most transmissions won't hold the gear, and also have a reduced range in comparison to just letting the computer do it.

I guess it might work well on some DCTs with paddle shifters, but I'll still stick with my original thought that it makes no sense. It ones thing to shift a manual tranny better than an auto shifts itself, but it's even harder to shift an auto tranny than it shifts itself.

The computer knows which gear will give you the best result for the conditions, better than you can know yourself. Therefore, why bother is my point.

 

[vavavroom]

From what I have observed modern cars cut fuel injection upon deceleration. When the RPMs approach no load/idle speed the injectors kick back in to keep the engine from stalling.

 

[vavavroom]

I think almost every automatic has this now but I've never seen nor heard these systems be liked nor appreciated very much. It's usually been my experience that it's mainly a gimmick and you get better results with putting the tranny in the appropriate mode (sport, tow/haul, etc).

Personally speaking, I've never found using them a pleasurable experience. What's worse, most transmissions won't hold the gear, and also have a reduced range in comparison to just letting the computer do it.

I guess it might work well on some DCTs with paddle shifters, but I'll still stick with my original thought that it makes no sense. It ones thing to shift a manual tranny better than an auto shifts itself, but it's even harder to shift an auto tranny than it shifts itself.

The computer knows which gear will give you the best result for the conditions, better than you can know yourself. Therefore, why bother is my point.

An automatic cannot anticipate, for example, an upcoming curve. Using a convenient paddle shifter or the manual override on the stick to down-shift before a curve makes sense, depending on your driving style.