Thud under gas pedal when taking off

[osteodoc08]

Engine or transmission mount?

 

[jking05]

Exactly its not the auto start stop. My engine doesnt always shut off when I stop and its obvious when it does. This happens with the engine running and it does feel like a rubber mallet tapping right under the pedal when you take off.

 

[duneslider]

Does it do it in 2h and 4a? Just curious if it is maybe a drive shaft clunk. Usually it isn't noticeable but sometimes there is enough play to get a clunk.

Could be a loose mount too, engine or transmission. (This would surprise me on something this new)

If you start rolling without pressing the gas pedal does it still do it? Or just hitting the gas from a stop?

 

[jking05]

Its 2WD. Just hitting the gas from a stop and it doesn't do it every time. It almost feels like something is catching right behind the pedal and slaps the floor when its pressed down more.

 

[Deadman]

Its 2WD. Just hitting the gas from a stop and it doesn't do it every time. It almost feels like something is catching right behind the pedal and slaps the floor when its pressed down more.

Floor mat? rubber boot?

 

[Cigarguy]

I almost liken it to slight play in a driveshaft that gets bound up when torqued (if that makes sense).

 

[firstford]

I have the same thing, funny if you ask the dealer they say, we can't reproduce it and this is the first time anyone complained about it.

 

[Andrew Roth]

I have a 2017 F150 as well with the same power train (gen2 3.5 w/10spd) and it does this thud too when you first step on the gas. I will describe it like a loose tennis ball in the bed of the truck. Bouncing into the tailgate on accel. I even had to get out and look and see if I had something loose rolling around. Kind of seems like it might be related to the front suspension becoming unloaded on accel.

 

[Artie]

I almost liken it to slight play in a driveshaft that gets bound up when torqued (if that makes sense).

So possibly a u-joint? Did I just date myself with that... I assume they still use those but what do I know.

 

[Soliyou]

This is not the same generation but could be a similar issue: