Eoc w/ automatic

[KCF3712]

How does EOC effect / harm an automatic transmission? If got a few good places to EOC where I live, but am worried about what it is doing to my tranny.

Thanks

KCF3712

[2003protege]

My understanding is that the transmission fluid is kept circulating by the turning of the engine. So EOC-ing could potentially cause the gears to turn without a flow of transmission fluid (i.e. lubricant). This is depending how your car is set up.

[cmj]

Why not just drop the car into neutral and coast for a while? I saw some good gains doing just that.

[EdKiefer]

Most conventional transmission have oil pump driven off inputshaft which spins with torque converter/flywheel.
So if engine is off then no oil pressure but for real short periods it might be ok, but I wouldn't risk it personally .

Edit: to be more specific the pump is driven from converter housing which is same as flywheel/crank, so even before inputshaft/torque converter output

The problem with neutral is the injectors are still firing where if you just left in gear (D) and let off gas injectors shut down on modern engine management systems until you hit idle speed .

[2003protege]

^this

[DonR]

I agree with what everyone said above.

I saw an ad in an RV magazine for an auxillary trans fluid pump to fit onto a vehicle being flat towed. In theory, if you can get the pump to turn on when you shut the motor off, you should be ok. I don't think I'm going to try it though.

Don

[KCF3712]

b

[2003protege]

Originally Posted by KCF3712

b

[some_other_dave]

Check your owner's manual. If it says that the car can be "flat-towed" (towed with all four wheels on the ground), then it is fine to EOC with it. If it says that you cannot, then leave the engine on, and coast in neutral.

DFCO results in more drag than shifting to N. So if you don't want to slow down, say you're doing pulse & glide, you would shift to N. If you were slowing down anyway (e.g., coming up to a red light) you might leave it in D to get some DFCO deceleration.

-soD