Has anybody experienced truck rolling back on a hill with an auto transmission. Is this normal?

 

Yep, don't know why it does that...do you?

 

Which Engine/Transmission do you have?

 

My truck does it and so does my wifes Expy.

 

5.4l Efi V8 Engine
Electronic 4sp Auto O/d Transmission
3.73 Limited Slip Axle

 

I have the same 5.4, LSD 3.73 rear end, FX4. Why does it roll back?

 

The reason for the rollback is a combination of the low idle speed and the stall of the torque converter. At the 600 rpm in drive there just isn't enough speed inside the torque conveter to keep the fluid inside the converter moving enough to keep the vehicle from rolling back on a hill. If you manually bring up the rpm with your foot to about 750 in drive, you'll see it will hold on a hill just fine. I noticed on my own truck, if I take my foot of the brake, sitting at a red lite, 9 times out of 10, the truck won't roll forward. It just has to do with the idle speed. There's nothing wrong with the transmissioin. Unfortunatly, the idle speed is not adjustable.

 

So to make it clear, use your left foot on the brake just like a manual clutch and step on the accelaration pedal with your right foot to increase the rpms to 750. Then gently release the brake. This should prevent rollback.

Thanks.

 

Mine (5.4 liter/3.55 LS rear, 4WD SCab) rolled back frequently when stopped on hills. I bought the super tuner, did the 87 octane tune, and I haven't had the problem in two months since. So you're probably right about the effect of the low idle rpm on the torque converter.

 

The rolling backwards on the hill is a nuisance but not a big deal. What concerns me is that when I shift from drive to reverse without being completely stopped, the truck will drift forward up to another six or seven feet. I know you are supposed to be stopped when you shift but this will happen when I am only doing half a mile an hour. I have to really hit the gas for reverse to catch so I start going backwards. This probably also has to do with the low RPM's not catching the torque converter.

 

I have been in a hurry and turn off my truck and thought I put it in park and it would roll and I would look and it would be in reverse. Might cost me one of this days.