I recently picked up a 08 f150 limited AWD.

The problem I am having is when the truck kicks itself into AWD I can feel a vibration in the gas peddle. I get the same vibration when I put it into 4 wheel drive. I've had it back to ford several times and they tell me everytime that they can't find anything wrong because no codes are coming up when they scan it. This is getting rather aggravating since a problem with the t-case will not trip any sensors for the check engine light to come on. When I purchased the truck it had 2 different tires on it and knowing that it is AWD I made the dealer install all new tires on it. But before they put the new tires on it I drove the truck for about 2 months. The dealership I purchased the truck at told me there is something wrong with the drivetrain but they can't fix it(it's a GM dealer)and that I would have to take the truck to ford.

Now that u know my problem here is my question. Is it normal to feel a vibration when the truck is in AWD?

Thanks in advance for any help.

 

I know the drive-shaft and axles are all spinning all the time as it's moving.
Also the tires on these AWD trucks flat spot from setting more then 8 hrs. and cause an out of balance condition(feel) for at least 10 miles of driving and then smooth out, maybe that's your problem!?
This truck scared the crap out of me when I first started driving it from all the pops and clacks that it was making but after talking with people that had AWD's vehicles they all said it's normal so I quit worrying about it and I haven't noticed anything since, it's just the way it is.
One thing I know for sure is two different size tires on a 4x4 vehicle is not good and may be what has caused your problem.

 

Thanks for the reply. This isn't the first AWD vehicle that I have owned but if is the first one that I can feel when it kicks in and out of AWD. It will do it after 1 mile or 100 miles doesn't matter how far it's been driven. As far as the 2 different tires on it I'm 100% sure that is the root of my problem. I drove the truck for about 2 months with the tires on it and every couple miles it would feel as if something was winding up in the rear and then it would bang as if a wound up spring was letting go and it would kick into AWD at the same time. As far as my experience goes what was happening was the rear limited slip was binding up cause it had 2 different tires on the rear and also because of this the computer was sensing 1 tire was spinning slower than the other and therefore would kick it into AWD. Now u have the problem of the drivetrain binding since the tires continued to spin at 2 different speeds.

 

And the problem continues........

Ford dealer had the truck for a week and rebuilt the rear diff. Great now I have new clutch packs in my diff and the truck feels smoother until it goes into AWD. Still feel the vibration and hear the low growling noise. Now I have an even bigger problem. Got around 8" of snow here in pa and put it in 4 wheel drive. As soon as I put a load on it front tires stop spinning and I just spin the rear. Put it back in AWD and truck goes everywhere I point her......

 

Sounds like a trip back to the dealer to me!

 

u need all 4 of the same brand/type of tire on a awd vehicle or this will happen. all purchased at the same time, you cant just replace one or 2 tires at a time. all 4 have to be replaced at the same time.

 

That's what I explained to the dealer before I purchased the truck and had the new tires worked into the deal. For some reason when the truck was traded into them they replaced only 1 tire. And because they replaced the one tire they were going to get the other 3 for me but they were on national backorder. I was back at the dealer every couple days to see if the tires had come in yet and I guess after about 2 months of this they must have been tired of seeing me. They finally ordered 4 new tires of a different brand. But the damage had been done.

 

dealer shouldnt have replaced just the one. most people dont know you cant treat a awd vehicle like that though. wait until you get all 4 replaced then if you still here pops and stuff you may need to bring it in to get serviced.

 

Is this a Ford dealership that you got the truck from?

 

They put 4 new matching tires on it about 2 months ago. But the damage has already been done.

And I purchased it from a GMC dealer. Should have known they wouldn't beable to understand fords technology.