Engine surge

[crowncrazy87]

Had a weird thing happen tonight. Was waiting in the drive through line and the Expy just tried to surge forward like I was pushing the gas while holding the brake. It has done this once before about a month ago.... Anyone have any ideas as to what is going on? There is not check engine lights or anything and it only does it for a second...

The Expy is an 02 with the 5.4.

 

[FordandPolaris]

I have had my truck do that too. The best answer I can think of is that the torque converter doesn't properly unlock and so it doesn't allow the vehicle to sit still like it is designed to. Mine hasn't done it in a couple of years and would only do it right after I came off the freeway or somewhere where the TC would have been locked in the first place.

It should not be locked in a drive through but it could be a possibility that it is locking at the wrong time, though I think it locks on pressure so that might not be possible.

Does it overpower the brakes?

 

[crowncrazy87]

Almost. It did it as soon as I stopped after moving up in line.