Gen III transmission

[NH Moto Expo]

So I did something that may seem foolish but I've done this with every car I've ever owned and never had a problem. Driving my 2006 Montero, I was coasting down a grade and slipped the truck into neutral. Then I switched the ignition from run to Acc. This usually does nothing,(except save fuel) but in this case there was a racket under the car and felt like it was still in gear. It was like letting out the clutch on a manual car. Like I say, I've done this in GM's, Dodges, Audi's and VW's all without incident.

Could the transmission be locked up? Keeping the flex plate attached to the engine? Is this normal for this car? Nothing seems to have come from it but I found it quite scary that if the engine died so did your ability to coast. This was in 2Hi not AWD setting.

 

[plh]

why would anybody do this...

 

[ManfromSnowyRiver]

Not actually sure, but this is a horrific idea. Modern vehicles on such a long grade are going to get ridiculous good gas mileage anyways, and everything is electronically controlled, so telling the car you are not driving anymore.....Not only is this extremely dangerous, its also illegal in most states. Should you drop the key to off the steering locks up and you crash, you also lose power steering and brakes. Additionally you lose compression braking by not being in gear. For 20 cents in gas or something? Not worth it. Hell you probably lose that much in brake pad wear by not being in gear and using brakes more.

 

[IncorpoRatedX]

My guess is that you eliminated all the computer control from the drivetrain and things probably got weird or resorted to their basic mechanical function. But something like this would normally be fine, think of flat towing a vehicle with a tow bar. People do that all the time with gen 1 & 2, same concept really, coasting in neutral with the steering unlocked. I'm not sure if anyone has experienced flat towing a gen 3, I wonder about the sophisticated 4wd system. I'm not familiar enough with the gen 3's components to provide insight though.

in the future, putting it in neutral but leaving it running and letting it idle while it goes down hill would be better, it keeps the cooling system flowing and the trans fluid flowing, which will help cool the truck down and make it easier on the truck for the next up hill climb. Hope others can post some helpful info.

 

[plh]

Not actually sure, but this is a horrific idea. Modern vehicles on such a long grade are going to get ridiculous good gas mileage anyways, and everything is electronically controlled, so telling the car you are not driving anymore.....Not only is this extremely dangerous, its also illegal in most states. Should you drop the key to off the steering locks up and you crash, you also lose power steering and brakes. Additionally you lose compression braking by not being in gear. For 20 cents in gas or something? Not worth it. Hell you probably lose that much in brake pad wear by not being in gear and using brakes more.

MFSR- I am totally with you.

OP NHME - you did read about the GM recall last year - right? Pretty well publicized.

 

[DangerAbe]

why would anybody do this...

No idea. My thought is that if the key was in ACC then the engine was not running but the vehicle is rolling with the trans in N. Which is a bad idea. Just like flat towing, rolling in N without the engine running can mean that the trans fluid pump is not pumping.

But I'm not a Montero guy.

 

[KyleT]

The front disconnect for the differential was trying to engage from the lack of vacuum. A sign also when the vacuum solenoids fail or start to fail. Do it in 4hi unlocked and it won't make the noise.

Yes not a good idea for many reasons as stated above, but also illegal in many states to roll in neutral much less with the motor off, killing power steering.

The truth is you will use more fuel starting and stopping the motor than you save by shutting it off. New direct injection motors are different than ours.




Sent from my iPhone using Tapatalk

 

[nckwltn]

In my younger days I once put a car in neutral while going down a freeway in Chicago, pulled the key from the ignition and had a buddy unlock the globe box to get a map or something "important".

I'm still here to tell the tale. It was a manual, so clutch in was a bit different than an auto in neutral.

You also lose a lot of braking power... so not a good idea to go to acc, but I've put vehicles in neutral on big hill descents on long drives to see what kind of pull the engine has.

I also like the idea of knowing how the vehicle systems will react in various states of operation.

I think I even coasted in neutral on one of my recent 4x4 outings where fuel was getting tight.

I would also think that coasting down hill is a common practice for long haul truckers. Just not on grades so steep that they would get out of control.

 

[Michael Brown]

Coasting with transmission in N is not damaging as long as the engine is on. It won't save fuel though. Modern engines with EFI are designed to run on minimal or no fuel in coasting situations. They shift the pulse width of the injectors or coils to almost zero to conserve fuel, but only in D where the transmission can keep the engine rotating. In N, the engine continues to operate under idle conditions with normal pulse width.

The Aisin 5-speed transmission (and any transmission designed in the last 20 years) also uses a locking torque converter to hold the transmission in gear like a manual to further save energy loss. The transmission needs oil flow from the pump with the engine running to maintain this state of operation. The 4-speed does not lock the converter clutch, so it does not behave this way.

The free-wheel clutch for the front axle is vacuum operated, so that was most likely the noise when the engine turned off. It tried to enter 4-Hi (AWD) without electronic assistance from the drivetrain, which also would not have let it operate over 45mph.


TLDR: Let the car coast in D with the engine ON. The electronics are designed to save as much fuel as possible in coast operation.

 

[montypower]

It was making noise because it automatically trying to engage park. I had some thing happen when ran out of gas. Don't put ignition into ACC if coasting in neutral.

 

[KyleT]

It was making noise because it automatically trying to engage park. I had some thing happen when ran out of gas. Don't put ignition into ACC if coasting in neutral.

The trans does not engage park automatically on a montero but they should coast in N all day long. Some other brands do with electronic button shift transmission like Lexus ect.


Sent from my iPhone using Tapatalk