Hi ..ive been with this doubt since a long time
Ive Always drive my car doing this :
In highway...im goin at 2500 rpm at 60MPH
when a downhill comes i shift to neutral to save gas
(rpms turn down to 600) ..and then on Drive again ..
and so on the city....im im Drive all the time and when the red light come i shift to N again ...its a harmful habit ??
i Don know..i have a TH 200C on a 2.8 V6 car...
Is this bad ?? Help i need to know cause all my friends do this
and we have no shift kit..only stock Trannys
Thanks ¡

 

i dont see any reason why it would be harmful.
maybe someone with more knowledge could help, but i think youll be fine.
~matt

 

I've always heard on auto's to never have in neutral while moving,unless being towed. I believe it's acceptable on manuals though...

 

actually, i remember reading somewhere that its illigal in some states to coast in neutral.

 

Durring the Great Depresion coasting downhill was called "Jewish Overdrive".
You're driving an auto, that's what the torque converter is for. Do you really save gas?

 

shifting to neutral while going downhill, not worth the time or effort, in an automatic car, as someone stated thats what the torque convertor is for, not to mention, when you put it back in gear, things get jerked back up to speed, shocking gears is bad.

on the subject of going to neutral while at a traffic light with an automatic car, yes i do, especially when its stop and go traffic, if the torque convertor is not trying to push the car, it will keep trans temp down a little, and as we all know auto trannys DO NOT like heat.

 

..........
I do think i save gas ...cause RPMS turn down from 1500 to 500
Now am i right ????
I dont know ..help

 

Don't know if it's harmful to coast downhill in neutral.

But since the trans pump essentially turns at the same RPM as the engine, and coasting downhill in neutral has the "back-half" of the transmission turning at "road-speed", I would feel better leaving the trans in gear just so the fluid is circulating with a bit more "ooomph".

 

No gas savings there...just extra wear on the brakes.

The only time your buring more fuel is when you open the throttle. If your going down hill nad not touching the gas pedal your not burning any other fuel then you would at idle. If it's a carb'd car then while it does tend to suck down a few more drops of fuel but the wear and tear on the rest of the car is costing you more than your saving.

 

It is never a good idea to coast in neutral with an auto trans, and don't tow an auto car in neutral. If you ever watch a tow truck towing an auto vehicle, they pick it up from the rear and make sure the steering wheel is locked in the center.
With the trans in neutral and vehicle moving the trans is still turning inside, but the pump isn't operating, so your trans isn't getting any lubrication at this point, never a good thing.

 

The pump is still turning when the transmission is in neutral as long as the engine is running.

 

But not at a rate sufficent for the speed the trans is running.

 

When I got my CDL, that was a question on the written exam. It has to do with mainting complete postive control of the vehicle at all times. A driver shouldn't have the tranny in neutral for more than one vehicle length. It may be just a truck thing though.

 

I was told that the pump didn't run in neutral by at least 5 people so far. It's a common misconception that the trans runs dry. And of course, when every one of these people told me this, it "happened to their friend".

You can't tow an auto trans car for long on it's rear wheels in neutral because since the trans isn't running, there's no fluid getting to the trans, so it can overheat (and hurt) the trans. That's why they say for long towing to disconnect the driveshaft, which isn't a hard involved procedure. 4 10mm strap bolts and a prybar is all that's needed.

 

tom on all my thirdgens/fourthgens 4 - 11mm bolts .

 

mine are either 3/8in or 10mm

 

I would tow my car from the rear wheels. Sits low enough as it is

 

I was taught to always be in a gear. If something happens and you need some quick power it won't be there if you are not in gear. I will gladly take the hit of fuel economy over not having complete control of my car. These are not economy machines, never will be (although they don't do too badly)

I have heard that while coasting the ECM severely kills the amount of fuel to the injectors so the fuel saving idea of shifting into neutral is moot. I kick the car out of OD iof I am moving slow or am in an area where the trans will have to keep shifting in and out of OD. But that is because I don't want my trans to shift any more often than it has to. That issue can be fixed within the prom though.

As far as towing goes. Flatbed it. I refuse any other means. I don't care if they have to get another truck out to me.

What you are reading is correct. When the engine isn't running the trans pump isn't either. If you tow it on the rear wheels for any length of time the internals are not getting the lubrication they need... NOT good.

 

Damn, mystikkal_69, you're right, they are 11's, aren't they. Oops. 10mm is just so easy to say! Thanks for the correction!

Omega, you're right, gas mileage saved would be very minimal... a TPS adjustment might help. The computer uses the TPS voltage for a few things, including idling, and activation of the TCC. From what I understand, I believe the TCC will unlock if you let off the gas! Makes sense, a connected drivetrain at idle would use more gas than a disconnected one.

 

TomP:

The tcc never unlocks in the 700R4 for probably the reason I stated before. You will know when you drive a car that unlocks during coasting!!

My dads '88 Delta 88 did. When he fist bought it and drove it home he found that the car would just coast for miles with very little drop in MPH. He turned around at took it back to the dealer claiming something was wrong with the trans. They said it was a feature of the car (economy) and was normal. It REALLY freaked him out. It would essentially free-wheel (as if in nuetral) when you let it coast. Our cars do not do that.


If you are that desperate to get a few MPG, learn how to enable the Highway mode in the ECM. It's a lot less harsh on the drivetrain, and pretty damn cool!

 

Maybe yours doesn't.

 

Apeiron, Could you explain? I was unaware that any of the 700R4's free-wheeled.

 

i think he means some basicly do. i know mine will slow extremely slowly in overdrive. i can roll on forever and no there is nothing wrong with my tcc. even on a 35mph road if i just let off the gas at 35 it will kick up to top gear if not there already and roll forever. with my new "stock" prom i am usually in 4th with the tcc locked at 35 mph now.

 

The TCC in my car unlocks when coasting in overdrive, and was designed to do so from the factory. I don't know if all models were supposed to work that way or not.