08 f150 5.4 swerve on highway
 

Hi,

i was wondering if this is a common problem on the fords.

i had the iwe issue long time ago and i got the both axles shafts, iwe actuators and the vacuum lines replaced. When i have it on 4x4 low or hi and drive it on the highway, the whole car starts to swerve. like how a snake would move around, that slithery move. it did this before the iwe/axles shafts were replaced as well. but i needed to get them changed anyhow.

if it's on 2wheel drive, it drives normally on highway.

any tips or things i should be looking at.

thanks.

I think you're describing the handling of ANY 4WD vehicle on hard (paved) surface when there's no traction problems such as snow or ice and you put it into 4WD Low or High. Those settings are NOT like AWD, and will cause handling problems. You should NEVER put the truck into 4WD on a hard surfaced highway! It misinterprets your steering inputs and tries to compensate, leading you to input more steering changes which repeat the cycle.

Save the 4WD for snow, ice or back country dirt or mud.

- Jack

that kinda makes sense.

what's better to use in snow? 4x4 high or low?

so if i drive on snow and put it into 4x4, i shouldn't have that same result as if the vehicle is swerving left and right?

Use 4x4 High to drive on a snow-covered road Do the same if it's icy too. 4x4 Low is for when you need extra traction and are moving at a slow speed. You would not get the "swerving" feel in snow if you are driving in 4x4.

I may not have this explanation quite right, but what 4 wheel drive does is it tries to get your front and rear wheels rotating at exactly the same rate. And, it delivers power to both axles. If you have a limited slip differential, power continues to be sent to the slower moving wheels, so, they can't rotate slower if they are on the inside of a turn. You won't notice this on a slippery surface, because the wheel that is not rotating at the right rate simply slips easily. It can't do that on a hard-surfaced, dry road.

In 2WD, all of the wheels can rotate at the exact rate they need to, in turns, or even to compensate for small steering inputs.

I think if you check your owner's manual, you'll find it tells you to NOT use 4WD on a road with good traction.

- Jack

If you don't have a copy of your OM, here's a link:

https://owner.ford.com/tools/account...r-manuals.html

You can shift back and forth from 2wd to 4 Hi at any reasonable speed. That's why it's called "shift on the fly". However, you must be stopped with your foot on the brake and in Neutral to shift in and out of 4 Lo.

AND, to maybe clear up your confusion re 4WD and AWD, as I understand it, 4WD tries to "lock" the two axles together by sending the same power to both. But AWD automatically shifts the power to the axle that has good traction (I suppose it acts a bit like a limited slip differential between the axles.) My truck has a version of AWD called 4WD Auto.. I've tried it in slippery conditions and was not impressed.

- Jack

Surely the opening poster wasn't driving on hard surface roads in 4Hi or 4Lo! Good way to kill a transfer case, prematurely wear all the driveline!

AWD has a differential like setup in the transfer case, lets front and rear operate at different speeds to allow for turns, tire pressures, etc.

4WD locks front and rear driveshafts together mechanically with no method of allowing any difference in speed … and it forces the front and rear axles to operate at the same speed, scrubbing tires and maintaining a high load on drivetrain. Even if tires are same sizes and perfectly matched tread depths, even slight turns change distance through a turn as steering front axle always tracks wider through a turn. The scrubbing of front tires on hard pavement will affect steering feel a great deal I'd think, but not gonna test with my trucks.