Turning off engine with an automatic
 

I've heard some posts saying that you shouldn't turn off the engine while coasting if you have an automatic. The only reason that I've found for this is that the transmission pump turns off. Are there any problems that could arise from turning off the engine? I P&G a lot and I'd like to start turning off the engine during long glides.

coasting
 

My thought is that without the engine on (and pump operating as you mention ),it's the same as towing an automatic transmission car with it's drive wheels on the ground,which usually burns up the transmission.

While the claims of damaging automatic transmission that are flat towed in neutral are true. This damage can occur over hundreds of miles consistently being towed in N. I EOC "Off" coast my automatic with no problems. My longest EOC is 1 mile and I do it every day. I have been doing so for the past 20K miles with no ill effect. Before doing it though I did flush my tranny and added synthetic transmission fluid, just in case ... LOL

I tried this with my Civic once. The car has to be in park to restart the car, so I had to pull over by the side of the road.

Anyone know how to get around this ?

I shift into Neutral several times on my 7 mile commute to work. I coast down a hill for around 3/4 of a mile ( google maps ).

I find that even when I am going down hill, shifting into N will allow the car to go from 45 at the top of the hill to around 56 MPH at the bottom of the hill.
When I leave the car in Drive, it actually seems to slow the car.
I'll verify this the next time I go into work.

I know for certain that placing the car in N on level ground will allow me to coast at least 175 - 200 yards farther than leaving it in Drive.

( Is there a problem with my transmission ? )

In my car, going down a hill with a steady grade, I can shift into neutral and it feels like i tapped the gas. On one car, as soon as I shift into neutral it goes from 50 to 55, and I start gaining on the cars ahead of me.

I was actually about 5-10 car lengths behind a ranger the other day when I shifted into neutral and I had to use the brakes just before the bottom of the hill because I was gaining on him so fast... he never used the brakes once.

http://ecomodder.com/forum/showthrea...anny-1153.html

Some good points in this thread and the link posted above. I looked up my vehicle in a link posted in taht thread (ability to flat towing, which can be done in my altima). Now I do a daily ~.7 mile EOC, which is about 1/10th of my daily commute. Pretty nice IMO.

No, you are right.

the transmission holds you back when coasting.

Neutral is better!

Neutral is certainly better than just taking your foot off the gas. So as long as your car is supposed to be able to be towed flat it's ok to turn off the engine, but if it's supposed to be raised then it might cause problems. What about an ignition kill switch, would that get around the problem of not being able to flat tow the car?

No. An ignition kill switch does nothing to address the problems some vehicle have with flat tow.

When you flat tow, the turning of the drive wheels turns some of the internals of the transmission. If the design of the transmission is such that the transmission fluid is pumped through the system in the same manner as when the engine drives the transmission, then everything is A-OK. If the design of the transmission is such that the transmission fluid is NOT pumped through the system in the same manner as when the engine drives the transmission, then parts of the transmission are subject to overheating - potentially leading to premature failure - particularly if you flat tow the vehicle for a significant distance.

i had a rental car this past week - was doing some work in Baton Rouge.
Was a Ford Fusion - V6 auto. was a nice car - had a built in average MPG ( did NOT have instantanious though).

There is a section of LA 1 that runs down along the mississippi river - very flat with some lights every few miles. I started EOC in N to those lights and the car behaved same as my Altima. No bad effects that i could tell.

So i got a little more bold. - Crossing the Mississippi river on Interstate 10, the bridge has a long down slope - probably > 1 mile. So i EOC in N down this section. By the time i got to the bottom of it - i smelled something and there were no other cars around. I assumed it was the transmission starting to heat up the fluid way to high - so i stopped doing the EOC there and let the Fuel Cut off "save" the fuel.

I know every car is different - but based on what i saw - EOC to stop lights is probably not going to kill the car.. But EOC for > 1 mile at > 60MPH is probably not a very good thing to do.

Steve

EOC w/Automatic
 

A few years ago, before I was quite as enlightened as I am today, I had a '95 Chrys. LHS--automatic of course. In the name of free miles, I EOC'd down about a 2 mile stretch at around 65 mph. When restarted, the trans wouldn't shift past second--on a 4 spd OD trans. I limped it to the repair shop the next day. About 1 week and $2500 later I was back on the road. So much for my "free miles".:(

Maybe find a hack for the ECU.

Or find the switch on the gear selector, and find how the wiring works, and see if you can make it so it starts in Neutral as well.

My 92 Trans Sport van is like this as well. None of my other older vehices are.

Testdrive is right. Your car must be described in the operator's manual as capable of being "flat-towed" or you severely mistreating your transmission. Even then, automatic transmissions are not designed or tested for being shifted in or out of gear at speed. There are other stress issues involved with these highly complex and delicate devices. I have seen Detroit cars with automatic transmissions lose their higher gears from being coasted several miles. I would never, never coast my automatic vehicles in neutral - even if they were described as being capable of flat towing. This is because flat towing does not involve putting the car in and out of gear at speed. My advice, don't do it. Ever. Period. If you want better mileage, get a manual or, better yet, an automatic manual transmission like the Smart is equipped with. That is the coolest high mpg transmission ever made.

I tried putting my Automatic be neutral when going up hills on the freeway. We'll, this gave me no gains the when I just drove at 17tps the whole way my previous night. I'm sorry this is probably not relevant but I thought I would share it.

kinda hard to go UP hills in neutral.......

probably need to explain 17tps also.....

TPS = Throttle Position Sensor?

Yes, tps. Tonight I will go to neutral on the down side of the hill, starting at the crest. I will not put the car back in gear until I drop 10mph from the start of neutral.

If you match revs correctly there's no additional stress. Same goes for a manual.

The transmission is the main reason NOT to buy a Smart. Slow shifting (which is bad for MPG according to EPA testing BTW), dim witted and short lived.

If it weren't for the transmission, I'd be driving a Smart Roadster, I'd still love to get one with a toasted engine/trans and swap in a motorcycle engine/ tranny.

My car will start in neutral. I've never tried it while driving though or in any other car so I don't know if yours will do the same

My 1998 accord starts in neutral I tried it today.

Overheating the transmission is a real risk..


Need an AUX pump to keep the fluid moving and lubricating..

Never turn off an automatic transmission to coast. The little fuel consumption savings aren't worth the cost of transmission repair or replacement.

And since we're on the topic of starting in neutral, my '04 Civic auto I used to have would not start in neutral.

I am a big fan of EOCing....a manual.

I am not at all a fan of doing it with any auto. Even if it does not harm the trans.

It simply comes down to the fact that manual restarts can happen in an instant to restore power steering/brakes. It takes longer with an auto, if it is possible at all.

The only way I might consider it is if there was no traffic around me at all.

Any car that the factory designed to be flat towed can coast in N engine off without fear of damaging the tranny. Cobalts are and I think the models before it were as well, back to the Saturn SL's. Electric Power steering the in Cobalt address the other issue.

The 2010 turned it's self off driving down the highway with cruise set at 55 a few days ago, just slipped it into N hit the key and it's running again.

I had an issue coasting in my (now ex) wife’s 2006 Ion, using the 4T45 transmission... in theory the transmission can handle it but the car wasn’t programmed to accept the car moving and zero trans pressure (from engine off) as an acceptable condition so it threw a code and put the trans in some kind of limp mode... I cleared the code and the trans went back to normal but I learned that day that not all vehicles can be EOC’d even though their components *should* handle it...

2010 cobalts were part of the ignition recall iirc

My 99 Saturn was supposed to be fine for flat towing, only issue I found was that the cruise control didn’t work if I eoc’d w/o coming to a stop, until the next time I actually stopped.

Yeah the cobalt have had their ignitions replaced, thinking back on that occurrence, there is a pretty big bump in the road right there and I have more keys than normal on my key chain, and that key is a fairly new walmart replacement, my son has been driving it with the original key and fob only and no reoccurrences. It also had a car with lock show up on the dash around that same time that I think is gone now.