Put Transmission in Neutral at Red Lights?

[bulldog-yota]

Are you guys serious???

The tranny will be fine just sitting in D at a light. The amount of work it needs to do in terms of absorbing the engine torque and not driveline move, is so little compared to when you actually drive and the torque converter is not locked. And even better when you tow something on an uphill and it is not locked.

As to putting it in neutral, shouldn't do too much apart from jerking a little bit everytime you put it in D.

All in all it is probaly better to just leave it in D instead of flicking and jerking it the whole time by putting it in N. But compared what the tranny has to do while driving this is small potatoes.

SOund like the AMsoil vs Mobil1 argument vs having no oil in the engine.

 

[Satman]

Do it all the time.
Out of gear The fan runs faster to help engine temp and a|c temp
Heck it's hot out there.

 

[Iman74]

I think it's just silly if the discussion is for automatics. If it's manual, many people do it, and have been doing it for years.

But I just don't get these extra steps people take with their automatics like shifting into neutral or park for that matter driving an automatic cars. Vehicles have gotten much more sophisticated, I don't see any benefit in doing this.

 

[alpha]

I think it's just silly if the discussion is for automatics. If it's manual, many people do it, and have been doing it for years.

But I just don't get these extra steps people take with their automatics like shifting into neutral or park for that matter driving an automatic cars. Vehicles have gotten much more sophisticated, I don't see any benefit in doing this.

I usually only do it if I'm tired of holding my foot down for a long time.. same reason i've done it in manual trannies, to get my foot off the clutch..

 

[nathannookie]

Pressing Brake Slows Engine?

Or maybe you've taken a load off of the alternator with the brake lights going off upon release of the brakes. A possibility???

Use your handbrake instead and see if that makes the same difference in the rpm when you release it.

The handbrake (footbrake) doesn't do it...BUT, I 'did' apply the footbrake, to hold the 4Runner in place, and tried it again.

Again, when I hold the regular brake pedal down, the engine slows just a bit. When I release it, it goes up a few RPM, and so on. I don't think the Brake lights put enough of a load on the alternator to slow the engine that much, so I'm guessing that the computer, or something, is slowing the engine.

 

[biglatka]

Re: Pressing Brake Slows Engine?

The handbrake (footbrake) doesn't do it...BUT, I 'did' apply the footbrake, to hold the 4Runner in place, and tried it again.

Again, when I hold the regular brake pedal down, the engine slows just a bit. When I release it, it goes up a few RPM, and so on. I don't think the Brake lights put enough of a load on the alternator to slow the engine that much, so I'm guessing that the computer, or something, is slowing the engine.

You've just proved it is the brake lights. When you put the handbrake (emergency brake) on the the brake lights don't (shouldn't) go on and as you said it didn't "do it" (no rpm drop) , but with the foot brake (regular brake) the brake lights do go on and you see a slight rpm drop. Right???

 

[nathannookie]

Re: Re: Pressing Brake Slows Engine?

You've just proved it is the brake lights. When you put the handbrake (emergency brake) on the the brake lights don't (shouldn't) go on and as you said it didn't "do it" (no rpm drop) , but with the foot brake (regular brake) the brake lights do go on and you see a slight rpm drop. Right???

No. I'll tell you why I doubt that the brake lights would put that kind of a load on the alternator. I turned on the parking lights, and even tried a spot light (more wattage), I plug into the cigarette lighter, and it didn't slow the engine. The headlights at 110 watts or so, put a little load on the alternator, but again, didn't slow the engine like applying the brake does.

Gotta wonder.

If you've got a 4th Gen try it and see.

 

[biglatka]

Re: Re: Re: Pressing Brake Slows Engine?

No. I'll tell you why I doubt that the brake lights would put that kind of a load on the alternator. I turned on the parking lights, and even tried a spot light (more wattage), I plug into the cigarette lighter, and it didn't slow the engine. The headlights at 110 watts or so, put a little load on the alternator, but again, didn't slow the engine like applying the brake does.

Gotta wonder.

If you've got a 3rd Gen try it and see.

I would've sworn it was the brake lights after your post about trying the emergency brake, but the headlights do draw more current, and if there was not the same or greater rpm drop when you put them on, then maybe it is something else connected with the brakes??

go figure!

But then again the computer does compensate for rpm drop when the engine is loaded up, like putting the air conditioner on. Sooooo maybe the headlights put it over some limit, then the computer adjusts the rpm up, somewhere around where it should be???? Just guessing (stretching) with that one.
Let us know if you figure it out.

 

[nathannookie]

Re: Re: Re: Re: Pressing Brake Slows Engine?

I would've sworn it was the brake lights after your post about trying the emergency brake, but the headlights do draw more current, and if there was not the same or greater rpm drop when you put them on, then maybe it is something else connected with the brakes??

go figure!

But then again the computer does compensate for rpm drop when the engine is loaded up, like putting the air conditioner on. Sooooo maybe the headlights put it over some limit, then the computer adjusts the rpm up, somewhere around where it should be???? Just guessing (stretching) with that one.
Let us know if you figure it out.

Yep, it's throttle by wire, so anything could affect it (the computer). I'm thinking it's a gas saving thing? Like why keep the engine running any faster than it has to if the truck is standing still. Also wondering if the brake system puts a load on the engine too, but it didn't really feel like that...but maybe. They are still vacume assist?

I never tried it with the truck in Neutral...I'll have to though. That would possibly answer the question about the brake system putting a load on the engine.

 

[bulldog-yota]

Guys please read up on auto trannies!!

The reason the engine slows when you depress the brake is that the torque converter is absorbing the difference between engine speed 600RPM or so and the drivetrain speed 0 when standing still. It has zip to do with the brake lights or anything else.

Next time do the same experiment against a hill that will hold the runner without pressing the brake.

The reaosn why you dont notice with the parking brake is simple, you dont normally shift without pressing the brake.

Also remember the engine CPU will monitor idle speed and adjust it for various conditions, so if you shift from D to N while standing still you see it jump slightly and then settle a bit higher than when you were in D.

 

[Satman]

:iagree:

 

[nathannookie]

Re: Guys please read up on auto trannies!!

The reason the engine slows when you depress the brake is that the torque converter is absorbing the difference between engine speed 600RPM or so and the drivetrain speed 0 when standing still. It has zip to do with the brake lights or anything else.

Next time do the same experiment against a hill that will hold the runner without pressing the brake.

But I did basically the same thing you suggested. I applied the parking brake (instead of being on a hill), and then did the experiment. The truck never moves, so the torque converter is under the same restraint...brake on or off.

I'd press the brake, and notice the engine slows a little. Releasing it makes the RPM go up a bit again....again the truck still held by the emergency brake.

 

[biglatka]

Re: Guys please read up on auto trannies!!

The reason the engine slows when you depress the brake is that the torque converter is absorbing the difference between engine speed 600RPM or so and the drivetrain speed 0 when standing still. It has zip to do with the brake lights or anything else.
So wouldn't you then expect the same response with the emergency brake applied instead?

Next time do the same experiment against a hill that will hold the runner without pressing the brake.
This would be changing two variables.

The reaosn why you dont notice with the parking brake is simple, you dont normally shift without pressing the brake.
We're not talking about shifting. The original query was: "Maybe I'm imagining things, but when I take my foot off the brake, after standing still in D, it seems that the engine throttles up a wee bit, almost like it knows you're about to take off. Maybe to save gas when standing? Don't know....who knows what the computer does."

Also remember the engine CPU will monitor idle speed and adjust it for various conditions, so if you shift from D to N while standing still you see it jump slightly and then settle a bit higher than when you were in D.
I think we both said something like this in our previous posts.

Bulldog,
Maybe we were a little off topic because we not talking about shifting from D to N or vice-versa. The discussion centered around the rpm change with the 4Runner being in Drive with the foot brake on vs. the emergency brake...nothing to do about the change in RPM during a shift from D to N.

So I don't think it has anything to do with the automatic per se, more like taking a load off of the engine and the CPU's response to it, as we theorized before.

 

[biglatka]

Re: Re: Re: Re: Re: Pressing Brake Slows Engine?

Yep, it's throttle by wire, so anything could affect it (the computer). I'm thinking it's a gas saving thing? Like why keep the engine running any faster than it has to if the truck is standing still.

Nathan,
I just thought of the Toyota Prius. It takes your last statement to the extreme. With the Prius when you stop for a light for example, the gas engine shuts down completely, only to be restarted when you step on the gas again. Of course, this may have nothing to do with what you're talking about though. Just a thought.

 

[the_josh]

this discussion is getting way too silly, and just plain outta hand...

 

[biglatka]

this discussion is getting way too silly, and just plain outta hand...

:iagree:

 

[Kanab]

Nathan,
have you tried my suggestion yet?

 

[dancojgl]

At the stupid lights we have in Reno, you almost have time to put the transmission in Park and take a nap...

—Dan

 

[bulldog-yota]

Nathan and biglatka,

The behaviour described on the 4Runner is exactly the same even old carburated auto's behave. SO dont try to read to much into it. You are forcing me to go look into it more

And as to the original question of does it help the tranny to be shifted into N for stopping in a light, I believe it has been aswered numerous times and it is no.

 

[nathannookie]

Nathan and biglatka,

The behaviour described on the 4Runner is exactly the same even old carburated auto's behave. SO dont try to read to much into it. You are forcing me to go look into it more

And as to the original question of does it help the tranny to be shifted into N for stopping in a light, I believe it has been aswered numerous times and it is no.

Yeah...I know the 'Shift into N' question is about dead now....but yeah, please go into why the RPM's go down when the Brake is applied. I'm just curious.

Oh, and I tried it in N, and the RPM's don't drop. Only happens in D.

AND, yes Pitbull, I tried your suggestion, re; running around the truck. I even bought the stopwatch. Works great.